Free Flip-Book Zoology Class 11th & 12th by Study Innovations

Super-order 2. Palaeognathae or Ratitae : (Gr., palaios old + gnathos
jaw; L., ratis, raft).
(1) Modern big-sized, flightless, running birds, without teeth.
(2) Wings vestigial or rudimentary; feathers without interlocking
mechanism.
(3) Rectrices absent or irregularly arranged.
(4) Oil gland absent, except in Tinamus and Kiwi.
(5) Sternal keel vestigial, or absent
(6) Clavicles are small or absent.
(7) Pectoral muscles poorly developed.
(8) Syrinx is absent
They are grouped in 7 orders as follows;
Order 1. Struthioniformes : (Gr., struthio, ostrich + form)
Examples – True ostriches (Struthio camelus) of Africa
Order 2. Rheiformes : (Gr., Rhea, mother of Zeus + form)
Examples – American ostriches or common rhea (Rhea americana).
Order 3. Casuariformes Examples– Cassowaries (Casuarius) of australia,
and New Guinea and Emus (Dromaius novaehollandiae) of New Zealand
Order 4. Apterygiformes Examples– Kiwis (Apteryx) or New Zealand.
Order 5. Dinornithiformes Examples – Moas (Dinornis maximus) of
New Zealand

cOrder 6. Aepyornithiformes Examples –Giant Elephant-birds of Africa

and Madagascar. Aepyornis titan.
Order 7. Tinamiformes Examples – Tinamou (Tinamus).

Super-order 3. Impennae
(1) Most modern, usually small-sized, flying birds.
(2) Wings well-developed ; feathers with interlocking mechanism.
(3) Rectrices present and arranged regularly.
(4) Pterylae are regular.
(5) Oil gland is present.
(6) Sternum with a well-developed keel.
(7) Pygostyle is present

Chapter 6 99

Example: Penguins.

Super order 4. Neognathae : The super-order Neognathae includes
several orders. For the sake of convenience they may be grouped into
at least 6 homogeneous ecological groups, as follows :
Group A. Arboreal Brids : It includes majority of birds spending most of
their lives in and around shrubs and trees.
Order 1. Passeriformes : (L., passer, sparrow + form). Feet are adapted
for perching, while beaks for cutting. Examples : Common house
sparrow (Passer domesticus), common house crow (Corvus splendens)
Order 2. Piciformes : (L., picus, wood pecker + form) It includes
woodpeckers, sap-suckers. Examples : Yellow fronted pied woodpecker
(Dendrocopos mahrattensis).
Order 3. Columbiformes : (L., columba, dove + form) It includes doves
and pigeons Examples : Blue rock pigeon (Columba livia). Green pigeon
(Crocopus), extinct dodo (Raphus)
Order 4. Psittaciformes : (L., psitacus, parrot + form) It includes parrots,
parakeets, etc. Examples : Large Indian parakeet (Psittacula eupatria).
Group B. Terrestrial Brids : These birds are perfectly able to fly but
spend most of their time walking or running on ground.
Order 5. Galliformes : (L., gallus, a cock + form) It includes gamebrids

cnotable for their palatability, massive scratching feet, short and

powerful flight. Examples : Red jungle fowl (Gallus), peafowl (Pavo
cristatus),
Order 6. Cuculiformes : (L., cuculus, cuckoo + form) It includes cuckoos.
Examples : Cuckoo (Cuculus canorus), Koel (Eudynamis scolopaeous).
Group C. Swimming and Diving Birds
Order 7. Anseriformes : (L., anser, goose + form) Aquatic birds such as
geese, swans and ducks belong to this order. Examples : Wild duck or
mallard (anas), kcommon teal (nettion crecca), bar-headed goose
(Anser indica)
Order 8. Coraciiformes : (Gr., korax, crow or raven + form) It includes
kingfishers and their allies. Examples : White breasted kingfisher

Chapter 6 100

(Halcyon smyrnensis), pied kingfisher (Ceryle rudis)
Order 9. Gaviformes : (L., gavia, sea mew = form) It includes marine
birds, called loons (gavia) represented by only four species.
Order 10. Podicipediformes or Colymbiformes (Gr. kolymbos, diving
bird) It includes grebes (Podicipes), often called divers.
Order 11. Procellariformes : (L., Procella, a tempest + form) It includes
tube-nosed, seabirds such as albatrosses (Diomedea).
Order 12. Pelecaniformes : (L., pelicanus, pelican + form) It includes
pelicans. Examples : Pelicans (Pelecanus).
Group D. Shore Birds and Wading Birds These aquatic birds seldom
swim or dive beneath the water to any great extent.
Order 13. Charadriiformes : (NL., charadrius, genus of plovers + form)
This order includes a rather diverse group of shore birds characterized
by long wading legs and webbed toe. Examples : Red wattled lapwing)
Order 14. Ciconiiformes : (L., ciconia, a stork + form) It includes long–
legged, marshy wading birds with long snake-like neck.Examples : Cattle
egret (Bubulcus ibis), heron (Ardea herodias), flamingo
(Phonicopterus).
Order 15. Gruiformes : (L., grus, crane + form) It includes crane-like
wading birds with long legs. Examples : Common coot (Fulica atra),
Group E. Birds of Prey

cOrder 16. Falconiformes : (L., falco,falcon + form) The diumal birds of

prey with sharp hooked beaks and strong curved claws.

Types of Feathers

1. Quills:

a. The quills are large feathers present in wings and tail.

b. It has a central axis called shaft.

c. A small proximal parts of the shaft is hollow and translucent
and is termed as calamus.

Chapter 6 101

d. The long-distal, solid, opaque part of the stem is known as
rachis.

e. An umbilical groove extends all along the ventral side of
rachis.

f. Small hole on the proximal end of calamus is known as
umbilicus, the hole on the distal end of calamus is known as
superior umbilicus.

g. Each vane is composed of parallel filaments, the barbs. Each
barb contains barbules.

h. The distal barbules of each barb bear small hooklets.

ci. Emu bird have an after shaft as long as the main shaft.

Chapter 6 102

2. Coverts: They are small feathers present in the wings and tail.
They fill up the gaps left between the bases of the quills. They
have short calamus in comparison to quills.

3. Contours : They are small feathers that cover the body. They
resemble the quills but their barbs are not so strongly joined and
can be separated easily.

4. Filoplumes : They occur beneath contour feathers, very small in
size, consists of long calamus bearing at the tip of a few weak free
barbs with barbules.

5. Down feathers : They cover the newly hatched bird also called as
natal covering or the nestling downs. They consists of short
calamus, reduced rachis bearing flexible barbs with short
barbules. They are found beneath contours.

6. Bristles : They have short calamus, a long rachis with a few
vestigeal barbs at its base. Bristles occur near the mouth in the

cfly-catchers.

7. The first digit of the hand (thumb or pollex), bears a tuft of small
feathers known as bustard wing or alaspuria or false wing.

Chapter 6 103

Mammalia:
General characters
(1) The mammals are air-breathing, warm blooded, viviparous, tetrapod
vertebrates having body covered with hairs.
(2) Two pairs of pentadactyle limbs, each with 5 or fewer digits. Hind
limbs are absent in cetaceans and sirenians.
(3) Exoskeleton includes non living horny, epidermal hairs, spines,
scales, claws, nails, hoofs, horns, bony dermal plates, etc.
(4) Skin highly glandular containing sweat, sebaceous (oil) and
occasionally scent glands in both the sexes. Females also have
functional mammary glands with teats producing milk for suckling the
young.
(5) Endoskeleton completely ossified. Skull dicondylic having 2 occipital
condyles. Cranium large. A single zygonmatic arch present. Otic bones
fused into periotic which forms tympanic bulla with tympanic. Each half
of lower jaw consists of a single bone, the dentary, which articulates
with squamosal bone of skull. Vertebrae with flat centra (acoelous).
Cervical vertebrae usually seven. Ribs bicephalous.
(6) Teeth may be of several types (heterodont), borne is sockets
(thecodont) and represented by two sets (diphyodont).
(7) Respiration always by lungs (pulmonary). Glottis protected by a

cfleshy and cartilaginous epiglottis. Larynx contains vocal cords.

(8) Heart four chambered with double circulation.
(9) Kidneys metanephric.
(10) Brain highly developed. Both cerebrum and cerebellum are large
and convoluted. Optic lobes small and 4 in number called corpora
quadrigemina. Corpus callosum present between both the cerebral
hemispheres. Cranial nerves 12 pairs.
(11) Sense organs well developed. Eyes protected by eyelids, the upper
one is movable. External ear opening is protected by a large fleshy,
cartilaginous flap called pinna. Middle ear cavity with 3 ear ossicles–
malleus, incus and stapes. Cochlea of internal ear spirally coiled.
(12) Sexes separate.

Chapter 6 104

(13) Fertilization internal preceded by copulation.
(14) Except egg-lying monotremes, mammals are viviparous and give
birth to living young ones.
Classification of Mammal
Subclass I prototheria : (Gr., protos, first + therios, beast). Primitive,
reptile-like, oviparous or egg-lying mammals.
Order 1. Monotremata. (Gr., monos, single + trema, opening), Cloacal
opening present Confined to Australian region. Examples :
Monotremes. Platypus or duckbill (ornithorhynchus), spiny anteater
(Tachyglossus = Echidna)
Sub class II. Theria : (Gr., ther, Theria are subdivided into 2 living
infraclasses)
Infraclass 1. Metatheria : (Gr., meta, between or after). Pouched and
viviparous mammals without or with a rudimentary yolk sac placenta.
Confined mostly to Australian region.
Order 2. Marsupialia : (Gr., marsypion, pouch). Young ones are born in
a very immature state, and complete their development while attached
to teats or nipples in the abdominal pouch or marsupium. Vagina
double, uterus double.
Examples : Marsupials. Opossum (Didelphis). Kangaroo (macropus),
koala (phascolarctos) Kangaroo is the native of Australia

cInfraclass 2. Eutheria : (Gr., eu, true + therios + beast) Higher viviparous

mammals with true placenta and without marsupium. Young ones born
in a relatively advanced stage. Eutherians constitute majority of living
mammals arranged in 16 orders.
Order 3. Insectivora : (L., insectum, insect + vorare, to eat) Small
insectivorous mammals with long pointed snout.
Examples : Mole (Talpa), common shrew (Sorex), hedgehogs
(Erinaceus, Paraechinus)
Order 4. Chiroptera : (Gr., Cheiros, hand + pteron, wing) It includes
flying mammals or bats in which forelimbs are modified into wings.
Hind legs short and included in wing membrane
Order 5. Dermoptera : (Gr., derm, skin + pteron, wing). Nocturnal in

Chapter 6 105

trees. Gliding with the help of skin folds. Examples : One living genus
Cynocephalos
Order 6. Edentata : (L., edentatus, toothless) Teeth absent or reduced
to molars. Without enamel. Examples : Giant ant eater (Mryrmecopha)
armadillo (Dasypus),
Order 7. Pholidota : (Gr., pholis, a scale) Body covered with large
overlapping scales with sparse hair in between. No teeth. Long and
protrusible snout used to capture insects. Examples : Single genus of
scaly anteaters pangolins (Manis)
Order 8. Tubulidentata : (L., tubulus tube like + dens, tooth)
Examples : Single genus of pig-like aardvark or Cape anteater
(Orycteropus)
Order 9. Primates : (L., primus, of the first rank) Generalized or
primitive mammals except for great development of brain. Mostly
arboreal. Eg. monkeys, apes and human beings.
Order 10. Rodentia : (L., rodo, gnaw) Largest order including usually
small gnawing mammals. Each jaw with one pair of long, rootless,
chisel-like incisors growing throughout life. No canines. Examples : Rat
(Rattus), Mouse (Mus) squirrel (Funambulus)
Order 11. Lagomorpha : (Gr., logos, hare + morphe, form) With a
second pair of small upper incisors behind first pair of large chisel like

cincisors. No canines. Examples : Rabbit (Oryctolagus), hare (Lepus)

Order 12. Cetacea : (Gr. ketos or L., cetus, a whale)
Large marine fish-like mammals well adapted for aquatic life with

pectoral limbs modified into broad paddle-like flippers. No claws, no

hind limbs and no external ears. The living Cetacea are divided into two

suborders Odontoceti (toothed whales) and Mysticeti (whalebone

whales).

Order 13. Sirenia : (Gr., siren, sea nymph). Large, clumsy herbivorous,

aquatic mammals with paddle-like forelimbs, and no hindlimbs. No

external ears. Muzzle blunt. Hairs few. Inhabit estuaries and coastal

Chapter 6 106

sea. Examples : Manatee (Trichechus), dugong (Dugong = Halicore),
recently extinct Steller's sea-cow (Rhytina)
Order 14. Carnivora : (L., caro, tlesh + vorare, to eat) Small to large
predatory, flesh-eating mammals. Examples : Dog (Canis familiaris),
Wolf (C. lupus), Jackal (C. aureus), Walrus (Odobenus), common seal
(Phoca)
Order 15. Hyracoidea : (Gr., hyrax, shrew + eidos, form) Small, guinea-
pig like mammals distantly related to elephants. No canines. Cheek
teeth lophodont. Example : Conies (Hyrax = Procavia).
Order 16. Proboscidea : (Gr., pro, in front + boskein, to eat) Largest
living land animals having large heads, massive ears, thick practically
hairless skins (pachyderm), bulky straight legs and 3 to 5 toes with
small, nail like hoofs. Prominent feature is the nose and upper lip
modified as an elongated proboscis or trunk. Two upper incisors
elongated as ivory tusks. Cheek teeth lophodont.
Examples : Indian or Asiatic elephant (Elephas maximus), African
elephant (Loxodonta africana)
Order 17. Perissodactyla : (Gr., perissos, odd + dactylos, toes) The odd-
toed hoofed mammals or ungulates with an odd number of toes (1 or

c3) incisors present in both jaws. Examples : Horse (Equus cabalus), wild

ass (Equus asinus), Zebra (Equus zebra)
Order 18. Artiodactyla : (Gr., artios, even + dactylos digit) The even-
toed hoofed mammals with an even number of toes (2 or 4). Incisors
and canines in upper jaw usually absent. Stomach four chambered.
Many with antlers or horns. Examples : Pig (Sus), common
hippopotamus (Hippopotamus amphibius), camel (Camelus), deer
(Cervus), musk deer (Moschus), sheep (Ovis).

Practice Test Paper

Chapter 6 107

1. Only poisonous lizard of the world is
(a) Draco (b) Heloderma (c) Sphenodon (d) Varanus
2. Carapace is present in
(a) Toad (b) Bird (c) Frog (d) Tortoise
3.Which is not aerial adaptation of Birds
(a) Single ovary (b) Pneumatic bone (c) Gizzard (d) Keeled sternum
4. Archaeopteryx called a connecting link, carried the characters of
(a) Reptile and bird (b) Reptile and mammal (c) Fish and amphibian (d)
Amphibian and reptile
5.Pneumatic bones of birds
(a) Increase the respiratory rate (b) Increase the heart beat rate (c)

cIncrease the CO2 output (d) Increase the buoyancy

6.The vertebrae of birds are characteristically
(a) Heterocoelous (b) Acoelous (c) Opisthocoelous (d) Amphicoelous
7.Egg-laying mammals are grouped as
(a) Eutheria (b) Prototheria (c) Rodentia (d) Metatheria
8.External ears are characteristics of
(a) Birds (b) Mammals (c) Birds and mammals (d) Mammals and reptiles

Chapter 6 108

9.Corpus callosum is present only in

(a) Amphibia (b) Reptilia (c) Birds (d) Mammalia

10.In which of following group of mammals, the placenta is absent

(a) Prototheria (b) Metatheria (c) Eutheria (d) Theria

11. Jacobson's organs present in the roof of mouth are used for…...

12. Body of Chelonia is encased in a firm shell of dorsal………….and
ventral plastron

13. A single living species, the “tuatara” or sphenodon punctatum of
New Zealand belongs to the order…..

14. What is autotomy
15. The only poisonous lizard in the world is …………….
16. The largest living lizard in the world is the ferocious dragon……….
17. What is the mode of action of neurotoxins ?

c18. What is furcula in aves

19. Briefly mention about types of teeth found in mammalia
20. Write briefly about marsupials

Answers and Solutions
1. b
2. d
3. c
4. a
5. d
6. a
7. b
8. b

Chapter 6 109

9. d
10. a
11. Smell
12. Carapace
13. Rhyncocephalia
14. Autotomy is voluntary breaking of tail to confuse enemy.

Tail of most lizards is easily broken off when threatened or seized
by a predator.
15. Heloderma (Gila monster)
16. Varanus komodoensis
17. Neurotoxins cause death by paralysis of respiratory muscles
and asphyxiation
18. Both the clavicles and a single inter clavicle fuse to form a V–
shaped bone, called furcula or wishbone
19. Teeth may be of several types (heterodont), borne is sockets

(thecodont) and represented by two sets (diphyodont).

20. Young ones are born in a very immature state, and complete
their development while attached to teats or nipples in the

cabdominal pouch or marsupium. Vagina double, uterus double.

Chapter 6 110

Structural organization in Animals Part 1

Animal Tissues:-

A tissue can be defined as a group of cells similar in structure, origin and function.

The word "tissue" was given by a French anatomist and physiologist Bichat (1771-1802). But the the term
tissue had already been coined by N. Grew (1682) in reration to plant anatomy.

An Italian scientist Marcello Malpighi (1628-1694) is "founder of histology".
He founded a separate branch for the study of tissues called histology.

TypeThe term 'histology' was given by a German histologist Mayer (1819).
Histology is also known as microscopic anatomy.
1. Epithelial tissueBichat (1771-1802) is considered as "Father of histology".
2. Connective tissuesTypes of Tissues
3. Muscular tissueDepending upon the location and function, animal tissues are categorised into four types

c4. Nervous tissue Origin Function

Ectoderm, endoderm, mesoderm Protection, secretion, absorption etc.
Mesoderm Support, binding, storage, protection,
Mesoderm circulation.
Ectoderm Contraction and movement
Conduction and control

1. Epithelial Tissue

The cells of the epithelial tissue/epithelium are placed very close to each other, separated by very thin layers of extra
cellular material. The neighboring cells are held together by cell junctions. The epithelial tissue rests on a non-cellular
Basement Membrane, which separates the epithelial tissue from the underlying connecting tissue.

The basement membrane is a non-cellular membrane composed of two layers.

a. The upper thin layer called as basal lamina (composed of glycoproteins and mucopolysaccharides secreted by
epithelial cells).

b. Lower thick fibrous layer called as reticular lamina, (composed of reticular fibres and collagen fibres which are
parts of the underlying connecting tissue).

Chapter 7 111

Blood vessel are not present in epithelial tissue. Materials are exchanged between epithelial cells and vessels of the
connective tissues by diffusion through the basement membrane.

Classification of epithelial tissue:-

Simple Epithelium

It is composed of a single layer of cells. The adjacent cells are held together with the help of desmosome, resting
on the basement membrane. Simple epithelium is found mainly on secretory and absorptive surfaces. It helps in nutrition,
excretion, secretion but not for protecting the underlying tissue.

i. Squamous Epithelium It consists of a layer of thin, flat cells with conspicous nuclei. The cells contain irregular

cboundaries that fit closely into those of neighbouring cells. Squamous epithelium forms the inner lining of lung

alveoli and blood vessels (Endothelium) and is also known as pavement membrane and tesselated
epithelium.

ii. Cubical Epithelium has cells which have polygonal outline, but appear cuboid in vertical section. It forms the
lining of small salivary and pancreatic ducts and thyroid vesicles. It participates in secretion, excretion and
absorption. The cells of cubical epithelium in absorptive surface often bear Microvilli on their free ends. It gives a
brush-like appearance to their free ends. They are,hence, called as Brush-Bordered Cubical Epithelial Cells
e.g., in proximal tubules of kidneys. Microvilli increase the area of the free surface of the cell and thereby
enhance absorption.

iii. Columnar Epithelium is characterised by the presence of tall polygonal columns like cells. The nucleus is mostly
located at the base of the cell. Columnar epithelium is present on the inner surface of the intestine, stomach
and gall bladder. It is also found in gastric and intestinal glands. The function of columnar epithelium is
secretion or absorption. The intestinal mucosa is lined by Brush-Bordered Columnar Epithelium which is
highly absorptive.

Chapter 7 112

iv. Ciliated Epithelium consists of columnar or cubical cells with cilia on their free surfaces. The function of the cilia
is to move particles, free cells or mucus in a specific direction over the epithelial surface. Ciliated epithelium is
present on the inner surfaces of some hollow visceral organs such as Fallopian tubes, bronchioles and small
bronchi. Ciliated columnar epithelium present in the ventricles of brain and spinal canal is called as ependyma.
Cilia is of two types (a) Kinocilia are montile cilia with 9+2 organisation, (b) Stereocilia-Basal granule
absent, non-motile, 9+2 organisation is absent. Stereocilia is found in some parts of the male reproductive
tracts such as the epididymis and vas deferens.

v. Pseudostratified Epithelium: It is present on the inner lining of trachea and large bronchi. Though, it

consists of a single layer of columnar cells but it appears two-layered, because some cells are shorter than the

others with their nuclie at a different level. The shorter cells do not have cilia and secrete mucus which traps

particles on the epithelial surface. The longer cells have cilia. The ciliary movements propels the mucus and the

particles towards the larynx. Pseudostratified non ciliated columnar epithelium is found in urethra of male and

parotid salivary gland. c

Chapter 7 113

Compound Epithelium

It is composed of more than one layer of cells. Only the deepest layer cells rest on the basement membrane. Being
multilayered, compound epithelia have little role in secretion or absorption, but they provide protection to the underlying
tissues against mechanical, chemical, thermal or osmotic stresses. Compound epithelia can be stratified or transitional.

i. Stratified Epithelium has many layers of epithelial cells. The deepest layer is composed of cuboidal cells. But
the morphology of the superficial layers varies in the stratified epithelia. In stratified cuboidal epithelium the
superficial cells are cuboidal. It lines the inner surfaces of larger salivary and pancreatic ducts. Stratified non-
keratinised Squamous Epithelium lines the moist surfaces such as those of buccal cavity, pharynx
and oesophagus. It has many superficial layers of living squamous cells and deeper layers of interlinked
polygonal cells. Stratified Keratinised Squamous Epithelium covers the dry surface of skin. It has several
superficial layers of horny, scale-like remains of dead squamous cells and several deeper layers of living polygonal
cells. Heavy deposits of an insoluble protein, keratin in the dead superficial cells make the epithelium
impermeable to water and highly resistant to mechanical abrasions. On the contrary, non keratinised stratified
epithelia cannot prevent water loss and afford only moderate protection against abrasions.

ii. Transitional Epithelium It is much thinner and more stretchable than the stratified epithelium. It has a single
layer of cuboidal cells at the base, 2-3 middle layers of large polygonal or pear-shaped cells and a superficial layer
of large, broad, rectangular or oval cells. It is present on the inner surface of the urinary bladder and
ureters. It allows for considerable expansion of these organs to accommodate urine, because stretching
sufficiently flattens and broadens the cells of superficial and middle layers.

Histologists have identified two more types of epithelia, which can not be included in any of the above types of
epithelia.
a .neuroepithelia cell of epithelia origin. These cells are specialized for sensory functions (e.g., cells of
taste bud).
b.myoepithelial cell, are branched cells that contain muscle proteins, such as myosin and actin. They are
specialized for contraction of the muscle cells of sweat glands, mammary glands and salivary glands.

cGlandular Epithelia
i. The cells of glandular epithelia are usually columnar or cuboidal. The glandular epithelium can be classified into
two types :
a. unicellular, composed of isolated glandular cells (e.g., globlet cell of alimentary canal), and
b.multicellular, composed of cluster of cells. A gland, with a single unbranched duct is called a simple gland.
The secretory part of the gland consists of epithelial cells arranged in the form of tubes (tubules) or sacs (acini,
alveoli) or a combination of both. The duct is also composed of epithelial cells. Tubular gland, found in the human
intestine, is an example of the simple gland. A gland with a branched system of duct is called a compound gland
in which the secretory tubule or acinus may be coiled or branched and opens into the single duct of the gland.
Compound glands are present in the pancreas and sub-mandibular salivary glands.

Types of simple gland

a. Simple tubular: present in the intestine (e.g., Crypts of Leiberkuhn).

Chapter 7 114

b. Simple alveolar: Terminal part forms alveolus e.g., Mucous glands in skin of frog, poison glands in
toad.

c. Simple coiled tubular: Terminal part is coiled e.g., sweat gland.

d. Branched tubular: Gastric glands in stomach.

e. Branched alveolar e.g., Sebaceous gland.

Types of compound gland

f. Compound saccular gland: e.g., Salivary glands, (sub-maxillary and sub-lingual).

g. Compound tubulo alveolar: They are tubular as well as alveolar. They are found in mammary glands,

cpancreas, parotid salivary gland, Cowper's glands and Bartholin glands.

ii. Exocrine glands have a secretory portion, which contains the cells for secretion. On the basis of mode of
secretion, glands can be classified into
a. Exocrine glands: They transport their secretions to the respective sites of action, for example, salivary gland,
tear gland, gastric gland and intestinal glands.
b. Endocrine gland: They transport their secretions to the respective sites of action via blood.
c. Heterocrine gland When a gland performs both exocrine and endocrine functions, it is called a mixed gland
or Heterocrine gland (e.g., the pancreas, testis, ovaries).

iii. On the basis of mode of secretion, glands can also be classified as:

a. Holocrine glands: In holocrine glands, the product of secretion is shed with the whole cell resulting
into its destruction. e.g., sebaceous gland

b. Merocrine glands: When the secretory granules leave the cell by exocytosis without loss of other

Chapter 7 115

cellular material, the glands are called merocine glands e.g., the Pancreas.

c. Apocrine glands: In aporcrine glands, only the apical portion of the cytoplasm is discharged along with
the secretory product. e.g. mammary gland and axillary sweat glands.

Specialized Junctions between Epithelial Cells

1. Tight junctions (= Zonula occludens): Plasma membranes in the apical parts
of the adjascent epithelial cells get tightly packed together or even fused to
form the tight junctions. They help to prevent leaking of substances across
the tissue.

2. Inter-digitations: They are interfitting, finger like membranes proccesses of
the adjascent cells. They increase the surface area of contact between the
adjascent cells and hence their adhesion.

c3. Intercellular Bridges: They are minute projections arising from adjacent cell
membranes to make contact with one another.

4. Gap Junctions: Allow cells to communicate with each other by cytoplasmic
connections between adjoining cells, for rapid transfer of ions, small
molecules and occasionally big molecules.

5. Intermediate Junctions (= Zonula adherens): They generally occur just
below tight junctions. The intercellular space at such places contains a
clear, low electron density fluid with a dense plaque like structure on
cytoplasmic side of each plasma membrane from which fine microfilaments
of actin (protein) extend into the cytoplasm. There are no intercellular

Chapter 7 116

filaments between the adjacent cell membranes. There is an adhesive
material at this point. They serve anchoring function.

6. Desmosomes (= Macula adherens): Help in cementing of neighboring cells
together. They are like zonula adherens but thicker and disc like junctions.
They have intercellular protein. The plaque-like structures (protein plate)
are much thicker. The microfilaments which extend from plaque-like
structure into the cytoplasm are not of actin, but of a keratin like proteins.
These microfilaments are called tonofirils. Desmosomes serve anchoring
function. Hemidesmosomes (single sided desmosomes) are similar to
desmosomes, but the thickening of cell membrane is only on one side.
Hemidesmosomes join epithelial cells to basal lamina (outer layer of

cbasement membrane).

Chapter 7 117

2. Connective Tissue:

Types of Connective Tissue:

1. Connective Tissue Proper

i. Loose - More matrix less fibre e.g., Adipose Tissue, Areolar Tissue

ii. Dense - More fibres less matrix e.g., Ligament, Tendon, White fibrous, Yellow fibres
2. Supportive Connective Tissue: eg. Bone, Cartilage

3. Fluid Connective tissue e.g., Blood / Lymph

Types of connective tissue fibers: (released by subunits secreted by fibroblasts)

• Collagen fibers, the most common fibers in connective tissue proper, are long, straight,
and unbranched.

• Elastic fibers contain the protein elastin and are branched and wavy, returning to their
original length after being stretched.

• Reticular fibers are the least common of the three, thinner than collagen fibers, forming
a branching, interwoven network in various organs.

Connective Tissue Proper:

Connective tissue proper cell types

• Fibroblasts/ Histiocytes /Clasmatocytes are the most abundant cells responsible for the
production and maintenance of the connective tissue fibers and the ground substance.

• Macrophages are scattered among the fibers which engulf (phagocytize) pathogens or

cdamaged cells encountered in the tissue; responsible for chemicals released that

mobilize the immune system into drawing more macrophages into an area.
• Fat cells are also called adipocytes. A fat cell contains such a large droplet of lipid that

the nucleus and other organelles are pushed to one side. The number of cells varies
from one tissue type to another, from one region of the body to another, and from one
individual to another.
• Mast cells are mobile connective tissue cells often found near blood vessels. The
cytoplasm is packed with vesicles filled with chemicals that are released to start the
body's defence system when the need arises. Mast cells produce-

Histamine - Inflammatory substance produced during allergic reactions.

Heparin - Natural anti-coagulant.

Serotonin - Vasoconstrictor

• Phagocytic and antibody-producing WBCs/ cart wheel cells may move throughout the
connective tissue increasing their numbers during an injury.

Chapter 7 118

Connective tissue proper types:

(i) Loose Connective Tissue: Consists of cells scattered within a amorphous ground substance of proteins, strengthened by a loose scattering of
fibres such as collagen, elastin, (which makes tissue elastic) and reticulin, which supports the tissue by forming a meshwork.

(a) Adipose Tissue: It is present beneath the skin, around kidneys, and in mesentery and bone marrow. In addition to, fibroblastss,
macrophages, collagen fibres and elastic fibres, the adipose tissue also contains large, spherical or oval cells called Fat Cells or
Adipocytes. The cytoplasm and organelles in adipocytes are surpassed by fat into a narrow annular layer just beneath the plasma
membrane. The adipose tissue synthesises, stores and metabolises fat.

Functions : c
i. Prevention of heat loss by forming a heat insulating layer beneath the skin.
ii. Forms shock absorbing cushions around kidneys and eyeballs.
iii. Acts as a food reserve.

(b) Areolar Tissue: It is present under the epithelia of many hollow visceral organs, skin and in the walls of arteries and veins. The areolar
tissue joins different tissues and forms the packing between them and helps to keep the organs in place and in normal shape.

(ii) Dense Connective Tissue: Fibres and fibroblasts are compactly packed. Orientations of fibres may be a regular or irregular pattern and
accordingly called dense regular and dense irregular tissues. In the dense regular connective tissues, fibroblasts are present in rows between
many parallel bundles of fibres e.g., tendons and ligaments. Dense irregular connective tissue has fibroblasts and fibres (mostly collagen)
oriented in different directions. Eg. in the skin, in perimysium, perineurium and bones as periosteum.

(a) White Fibrous Tissues : Contains only a few fibroblasts scattered among the dense network of thick collagen bundles. It hashigh tensile
strength. eg. found at the joint between skull bones making them immovable.

(b) Tendons : It is a very dense, strong and fibrous connective tissue having thick parallel bundles of collagen fibres. A few flat tendon cells

Chapter 7 119

are present in a single rows between the collagen bundles. Tendons join a skeletal muscle to a bone.
(c) Ligament : Ligaments join bones to bones at joints and hold them in position. Excessive pulling of ligaments causes sprain. Ligaments

are composed of bundles of elastic fibres and few collagen fibres.
Mummies still have their arteries intact due to well preserved elastic fibres.

(d) Reticular tissue : consists of star-shaped reticular cells whose protoplasmic processes from a net work. They cells are phagocytic.
Matrix and other types of cells are also present in spaces of network. Reticular tissues are present in the spleen, lymph nodes, bone
marrow etc.

c

Supportive connective tissue
(1)Cartilage : Cartilage is a solid, semi-rigid flexible connective tissue. Chondrocytes are large cartilage cells occurring in groups of 2 or 3
cells in small spaces (lacunae) in the matrix.

Chapter 7 120

(a) Hyaline Cartilage: the matrix is apparently fibre-less, glass-like (hyaline) but translucent. It is found in the larynx, nasal septum,
(b) tracheal rings and ribs.

(d) White fibrous cartilage: contains rows of chondrocytes between thick dense bundles of collagen fibres. It is found at joints between
(2)Bone vertebrae. Collagen fibres make such joints strong, but less elastic and only slightly movable

Yellow elastic fibrocartilage: It contains a dense network of yellow elastin fibres scattered between chondrocytes. It constitutes the

cEustachian tube, epiglottis and pinna of ear.
(i) It is a solid, rigid connective tissue whose matrix has deposition of apatite salts of calcium and phosphorus. e.g., hydroxyapatite salts
and fluoroapatite salts.

(ii) About 60-70% of bone is composed of inorganic matter and 30-40% of organic matter.

Chapter 7 121

(iii) If put in HCL, the bone becomes decalcified, soft and flexible but not in KOH.

(iv) Osteoblast are cells which form bone and secrete ossein protein.

(v) Osteocytes are metabolically inactive bone cells present in lacuna.

(vi) Bone is a solid, rigid, strong connective tissue whose matrix is heavily deposited with apatite salts of calcium and phosphorus. Flat
irregular spaces called Lacunae are found in the solid matrix. Each lacuna has a flat bone cell or Osteocyte. A bone cell has irregular
shape with long cytoplasmic processes which extend into minute canals (Canaliculi) radiating from each lacuna.

(vii) Compact Bone constitutes the dense outer layers of all bones and is composed of many parallel, longitudinal, column-like structures

c3. Matrix occurs in concentric lamellae.
called Haversian Systems, cemented to each other. Haversian canals are connected to each other by Volksman canals. In each
Haversian system, many concentric layers (Lamellae) of bony matrix encircle a longitudinal central canal (Haversian Canal). Haversian
Canal carries blood vessels and nerves. Lacunae containing osteocytes occur in a layer between two lamellae.

(viii) Spongy Bone - The ends of long bones are made up of an open lattice of bone called spongy bone. The spaces within have marrow,
where most blood cells are produced. Spongy bone has no concentric organisation like the Haversian system. It is composed of a
network of many fine irregular bony plates or Trabeculae. Each trabecula consists of many irregularly arranged lamellae with lacunae
between them. It has red bone marrow. Spongy bone is also called as cancellous bone and is found in epiphysis i.e. the ends of long
bones.

Differences between Bone and Cartilage

S.No. Bone Cartilage

1. Matrix is composed of tough inflexible material, called ossein. Matrix is composed of a firm, but flexible material called chondrin.

2. Matrix is impregnated with salts, chiefly calcium phosphate and Matrix is impregnated with calcium salts only in calcified cartilage.
carbonate.

Matrix occurs in homogenous mass.

4. Matrix contains fibres, but these are indistin-guishable. Matrix may contain fibres, which may or may not be distinguishable.

5. Bone cells (osteocytes) lie in lacunae singly. Growth in bone is Cartilage cells (chondrocytes) lie lie singly or in groups of two or four.
bidirectional. Growth in cartilage is unidirectional.

6. Osteocytes are irregular and give off branching processes Chondrocytes are oval and devoid of processes.

7. Lacunae send out canaliculi for the processes of bone cells, which Lacunae lack canaculi.
extend into these minute canals.

8 There are outer and inner layers of special bone forming cells, the Cartilage grows by division of chondroblasts.
osteoblasts that produce new osteocytes, which secrete new
lamellae of matrix.

9. Bone of surrounded by a tough sheath, called periosteum. Cartilage is surrounded by a farm sheath, called perichondrium.

Chapter 7 122

Types of Bones:

i. Cartilage bones / Endochondrial / Replacing bones - They are formed by the replacement of cartilage by the bone e.g.,
humerus, femur vertebrae, girdle bones except clavicle. Chondroclast are cartilage eaters.

ii. Membrane / Investing bone / Dermal - e.g., skull bones, clavide. The bones are formed in the dermis of the skin and are
invested over the already present cartilage.

iii. Sesamoid bones - They are formed by the ossification of the tendon by bone e.g., Patella

iv. Visceral bones - They are those bones which get detached from the skeleton and come to lie in visceral organs e.g.,
a. OS cordis - Present in interventricular septum of heart of deer.

b. OS falciparum - Palm of mole.

c. OS penis - Penis or rat and carnivores.

d. OS palbebrae - In the eyelids of crocodile.

e. OS rostralis - Snout of pig.

Fluid connective tissue (Blood):

The cells of blood are quite distinct from other connective tissue cells, both in structure as well as functions. The extra cellular material
in blood is fluid without fibres. Fluids outside the cells are called Extra cellular Fluids (ECF). Viscosity of blood is 2.5 times higher than
water.

The extra cellular material in blood is a straw-colored, slightly alkaline (pH 7.4) aqueous fluid called Plasma.

Constituents of blood collectively called the Formed Elements float in the plasma. Formed elements include blood cells and blood

cplatelets. Blood cells are of two types-Erythrocytes and Leukocytes.

Plasma: 123

Chapter 7

The blood plasma has three major classes of proteins viz. serum albumin, serum globulins and fibrinogen. Plasma proteins act as a
source of proteins for tissue cells. Albumin and globulins retain water in blood plasma by their osmotic effects. A decrease in plasma
proteins leads to filteration out of excessive amount of water from blood to tissues. That is why hands and feet are swollen with
accumulated fluid (oedema) in persons suffering from deficiency of proteins in diet. Albumins and globulins also transport several
substances such as thyroxin and Fe3+ in combination with them. One class of globulins, called immunoglobulin, act as Antibodies.
Plasma proteins also maintain the blood pH by neutralizing strong acids and bases. Thus, they act as Acid-Base-Buffers.

Plasma is slightly alkaline non living inter-cellular material constituting about 60% part of the blood. It is a pale yellow, transparent and
clear fluid.

Composition of Plasma. Plasma constitutes 55-60% of blood volume.

1. Water - About 90% to 92% of the plasma is water. Solids constitute about 8% of the plasma.

2. Minerals Salts - They include chlorides, bicarbonates, sulphates and phosphates of sodium, potassium, calcium, iron and
magnesium. All salts constitute about 0.9% of plasma. Buffer of the blood is sodium bicarbonate.

Bicarbonates and chloride salts of Na, K and Ca are found in blood plasma. Co, Fe, SO4, & HCO3- are also present.

3. Nutrients – They includes glucose, fatty acids, phospholipids, amino acids, cholesterol, fats, nucleosides, etc. Minerals salts
have been given above.

4. Plasma proteins - They constitute about 7 to 8% of plasma. They mainly include albumin 4.4%, globulin 1.5%,
immunoglobulin, prothrombin and fibrinogen 0.3%.

5. Defence compounds - Immunoglobulin acting as antibodies, some other substances such as lysozyme and proper din (a large
protein) are always present in the plasma. They destroy bacteria, viruses and toxic substances entering into the blood from
outside.

6. Excretory substances - They includes ammonia, urea, uric acid, creatinine, etc.

c7. Dissolved gases - Water of plasma contains oxygen, carbon dioxide and nitrogen in dissolved form.

8. Anticoagulant - Blood plasma contains a conjugated polysaccharide, the heparin that prevents coagulation of blood inside
blood vessels.

9. Hormones - secreted and released in blood by endocrine glands.

10. Vitamins and Enzymes - Vitamins and enzymes are present in the blood plasma.

Functions of Blood plasma - These can be summarized as under (i) transport, (ii) retention of fluid in blood, (iii) maintenance of blood
pH, (iv) body immunity, (v) prevention of blood loss, (vi) conducting heat to skin for dissipation and (vii) uniform distribution of heat all
over the body.

Blood Glucose

Glucose is mainly absorbed in the small intestine. It is also absorbed in stomach. Excess of glucose is converted into glycogen in the
liver and muscles by insulin hormone. Whenever it is required glycogen is converted into glucose by glucagon hormone. Normal blood

Chapter 7 124

glucose level is about 80 - 100 mg per 100 ml of blood 12 hours after a normal meal. Its concentration rises soon after a carbohydrate
rich diet. If blood glucose level exceeds 180 mg per 100 ml, it starts coming in urine, a condition called glucosuria. Fasting glucose is 70
- 110 mg/dl*. Glucose PP* is 110 - 140 mg/dl. If it a higher it causes diabetes mellitus (hyperglycemia). If it is less it causes
hypoglycemia (less amount of glucose in blood).

Blood Cholesterol

Cholesterol is quite useful in limited amount. It is used in the synthesis of bio membranes, vitamin D, bile salts and steroid hormones.
The normal normal amount of cholesterol is 80 - 180 mg in 100 ml of blood plasma. Cholesterol appears in blood either by intestinal
absorption of fats or by synthesis in the liver or by both. Saturated fats such as ghee and butter increase cholesterol level in the blood
that may lead to its deposition in the internal wall of the blood vessels like arteries and veins which causes high blood pressure and
heart problems.

Functions of Plasma Proteins

1. Prevention of blood loss - Fibrinogen and prothrombin have a role in blood clotting.

2. Retention of fluid in the blood - Albumin and globulin retain water in blood plasma.

3. Body immunity - Some globulins called immunoglobulin (glycoprotein's) act as antibodies in blood and tissue fluid.
4. Maintenance of pH - Plasma proteins act as acid-base buffers i.e. they maintain pH of the blood by neutralizing acids and

bases.

5. Transport of certain materials - Thyroxin hormone bounds to albumin or specific globulin for transport in the plasma.

6. Distribution of heat - Plasma proteins helps in uniform distribution of heat all over the body.

7. Enzymes - Some enzymes also occur in the plasma.

Blood Cells - Erythrocytes

cErythrocytes (red blood corpuscles or RBC) are the most abundant of the formed elements of blood. The most important characteristic

feature Of RBCs is the presence of hemoglobin, the red oxygen carrying pigment. The total number of RBCs per microlitre (1 l = 1mm3
= 10-6) of blood is known as the Total Count of RBC. It is about 5 millions and 4.5 millions in adult man and adult woman respectively.
The total count becomes low in anaemia and after profuse bleeding. Abnormal rise in the total count of RBC is called Polycythemia.
Anaemia is caused due to the deficiency of folic acid, vitamin B12 and hemoglobin.

The shapes and sizes of RBCs vary in different classes of animals. In fishes, amphibians, reptiles and birds RBCs are usually nucleated,
oval and biconvex. In mammals, they are non-nucleated, biconcave and circular. Only camel and llama possess oval red blood
corpuscles. Old and worn out RBCs are phagocytosed and destroyed by macrophages. During this process, the pigment part porphyrin
of hemoglobin is catabolised to the yellow pigment Bilirubin which is excreted in the bile. The pale yellow colour of plasma is largely
due to billirubin.

If a sample of blood added with potassium or sodium oxalate is centrifuged at a high speed in a graduated centrifuge tube (hematocrit
tube), the centrifugal force rapidly sediments the RBCs at the bottom of the tube. They get packed into a solid, red, bottom layer,
wherease the leukocytes form a thin, buff-coloured layer. From the graduations on the tube, the relative volume of erythrocytes may
be read as a percentage of the total blood volume. It is called the Hematocrit Value or Packed Cell Volume. It normally forms 45

Chapter 7 125

percent of the blood volume.

RBC of mammals are circular, biconcave, non-nucleated except in family camelidae. e.g., camel The camel has non-nucleated and oval
RBCs. Largest RBCs are found in amphibian whereas smallest RBC are in mammals. In mammals smallest RBC are found in 'Musk Deer'
Tragulus javanicus (1.5 m). In mammals largest RBC are found in elephant. (9.4 ).

Life Span

Life span in man = 120 days
Life span in frogs = 100 days

Count of RBC
In Man = 5 to 5.5 million/Cu. mm
In woman = 4.5 million/Cu. mm
In embryo = 8.5 million/Cu. mm
Daily destruction of RBC = 1%

ESR (Erythrocyte sedimentation rate): is measured by Wintrobe's method. It is the rate of setting down of RBC and is also estimated

cby Westegren's method. ESR is very useful in diagnosis of various diseases like tuberculosis, ESR in men is 0-5 mm/hour and in women

it is 0-7 mm/hr in Westegren method.

Haemocytometer: is an instrument used for counting the number of both W.B.C. and R.B.C.

Rouleaux: In resting and slowly flowing blood, the RBCs aggregate to form rouleaux (the RBCs are piled on top of each other).
Fibrinogen facilitates rouleaux condition.

Bone marrow: It is the main site for RBC formation.
Structure of RBC of man: Biconcave, non-nucleated bounded by Donnan's membrane. (plasma membrane of RBC). Haemoglobin is
filled in RBC which is vasculatory pigment or respiratory pigment.

Normal range of Hb

Men 15.5 2.5g/dl (dl = deciliter)
Women 14.0 2.5g/dl

Chapter 7 126

Infants 16.5 2.5g/dl

Structure of Haemoglobin: Each molecule of haemoglobin has 4 molecules of haem and 1 molecule of globin. They are attached by co-

ordinate bond. Haem is protoporphyrin compound and essentially has 4 pyrrole groups joined together and forms ring structure. In Hb

Fe is present in (Fe++) Ferrous form. Hb = Haem 5% & Globin 95%. Globin is made up of 4 polypeptide chains.

Practice Test Paper

1. Cells of the epithelial tissue rest on a basement membrane which is made up of
(a) Monosaccharides (b) Mucopolysaccharides (c) Disaccharides (d) Lipids
2. The cells of a tissue are similar in

(a) Structure (b) Function (c) Origin (d) Both (a) and (b)
3. The intercellular matrix is negligible or absent in which of the following tissue

(a) Connective tissue (b) Epithelial tissue (c) Muscular tissue (d) Cardiac tissue c
4. The basement membrane acts as

(a) Plasma membrane (b) Plasmalemma (c) Both (a) and (b) (d) None of these
5. The filaments arising from desmosomes are called

(a) Tonofibril (b) Tonofilament (c) Both (a) and (b) (d) None of these
6. Pseudostratified epithelium is always

(a) Single layered (b) Double layered (c) Multilayered (d) Uncertain
7. Most of the glands of the body are of

(a) Holocrine type (b) Merocrine type (c) Apocrine type (d) None of these
8. Reproductive cells (germinal epithelium) are made up of which of the following epithelial tissue

(a) Cuboidal (b) Columnar (c) Squamous (d) Sensory
9. In chordates the peritoneum covers

(a) Heart (b) Skin (c) Kidney (d) Liver
10. Covering of lungs is called

(a) Pericardium (b) Pleura (c) Peritoneum (d) Serosa
11. Schneiderian membrane is found in

(a) Nasal passage (b) Trachea (c) Bowman’s capsule (d) Loop of Henle
12. Cells of squamous epithelium are

(a) Tall with elongated nuclei (b) Cube like (c) Flat and tile like (d) Columnar or cuboidal in shape
13. Which of the following makes heart wall more thick

(a) Pericardium (b) Epicardium (c) Myocardium (d) Endocardium
14. Internal surface of large intestine is

(a) Lined by muscular tissue (b) Lined by epithelial tissue (c) Lined by both types of tissue (d) Lines by all four types of tissue
15. Desmosomes are the feature of

(a) Epithelial tissue (b) Nervous tissue (c) Muscular tissue (d) None of these
16. Simple epithelium is

(a) One cell thick (b) Two cells thick (c) Two or three cells thick (d) All of these
17. The cellular layers in epidermis of skin consists of

(a) Glandular cells (b) Columnar cells (c) A squamous stratified cornified epithelium (d) A complex stratified epithelium
18. Pavement epithelium is another name for

Chapter 7 127

(a) Cuboidal epithelium (b) Ciliated epithelium (c) Simple squamous epithelium (d) Stratified epithelium
19. Rapid healing of wounds is found in
(a) Epithelial tissue (b) Muscular tissue (c) Connective tissue (d) Nervous tissue

c

Chapter 7 128

20. Microvilli are present in
(a) Stratified squamous epithelium (b) Cuboidal epithelium (c) Columnar epithelium (d) Ciliated epithelium

Answers

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
bdbc c abadbac c baac c ac

c

Chapter 7 129

Structural organization in animals Part 2

Blood Cells - Leukocytes

Leukocytes (white blood corpuscles or WBC) do not have hemoglobin and hence are colourless. Leucocytes are nucleated
cells. They are o two major classes : granulocytes (with cytoplasmic granules) and granulocytes (without granules).
Granulocytes are of three types, viz. neutrophils, eosinophils and basophils, each with a lobed nucleus. Agranulocytes are of
two types, viz. lymphocytes and monocytes. Neutrophils and monocytes protect the body against microbes by phagocytosis.
Lymphocytes produce antibodies in the blood to destroy microbes and their toxins. The number of leucocytes per microlitre
(1 l = 1 mm3 = 10-6) of blood is called the Total Count of WBC. It is normally 5000 in humans. It may rise abnormally in
acute infections (e.g., pneumonia), inflammations (e.g., appendicitis) and malignancies (e.g., leukemia). In some cases such
as folic acid deficiency, the total count falls abnormally (leucopenia). The total count of WBC is also of diagnostic value in
some diseases. Monocytes have kidney shaped nucleus. The process by which monocytes and neutrophil squeeze through
thin capillary wall is called Diapedesis.

Differential Leukocyte Count (DLC) Leukocytes (2 types):

1. Granulocytes with granules in cytoplasm
(3 types) on the basis of staining characteristic of cytoplasmic granules and shape of nucleus
1. Neutrophils (40 - 75%)
2. Eosinophils (1 - 6%)
3. Basophils (0 - 1%)

2. Agranulocytes without granules

1. Monocytes (2 - 10%)
2. Lymphocytes (20 - 45%)

a. Neutrophils: They are maximum in number, stain equally with both basic and acidic dyes and haved many lobed

cnucleus, granules are in abundance in cytoplasm and help in phagocytosis.

b. Eosinophils: They have bilobed nucleus, stain with acidic stains. Their number increases during allergic reactions
(Eosinophila).

c. Basophils: They stain with basic dyes. The nucleus is 'S' shaped. Coarse granules are few in cytoplasm. Basophiles
release heparin and histamine in the blood and have a function similar to the mast cells.

d. Lymphocytes have large and rounded nucleus. The cytoplasm forms a thin peripheral film. They have the stain
cells in the bone marrow and are differentiated in the bone marrow or in the thymus. Lymphocytes are of two
types B-lymphocytes and T-lymphocytes.B-lymphocytes produce antibodies against antigens and they mature in
the bone marrow.

e. Monocytes are the largest leucocytes (12-15 m). The nucleus is kidney shaped. They are produced from bone
marrow from monoblast cells. They help in phagocytosis.

Chapter 8 130

Differences between different types of Leucocytes cBasophils

Character Lymphocytes Monocytes Eosinophils 0.5-1% Neutrophils
Coarse (Acidophils)
Number/Percentage 20-25% 2-10% 2-3%
Coarse 60-65%
Granules in Absent Absent
cytoplasm Eosinophilic Fine

Staining of Basophilic Basophilic Bilobed Basophilic Neutrophilic
cytoplasm Bone marrow

Nucleus Rounded Bean-shaped S-shaped 3-lobed Multilobed

Site of formation Lymph nodes Bone marrow Bone marrow Bone marrow
spleen, thymus
tonsils, Peyer's
patches Bone
marrow

Life span Few days or 10-20 hours in 4-8 hours in blood 4-8 hours in blood 4-8 hours in blood
even years the blood tissue,
months or even and 4 to 5 days in and 4 to 5 days in and 4 to 5 days in
years
tissue tissue tissue

Function Antibody Phagocytic Important role in Secretion of Phagocytic
formation immunity
Blood platelets antiallergic heparin histamine

and serotonin

Blood platelets also called throbocytes, are non-nucleated, round or oval, biconvex disc-like bodies.
They are 2-3 micromitres in diameter and their number normally varies from 0.15 to 0.45 million per
microlitre of blood. They bud off from the cytoplasm of very large Megakaryocyte cells of bone marrow.
Their normal life-span is about a week. When a blood vessel is injured, platelets get clumped at the
injured spot and release certain chemicals called Platelet Factors. These promote blood coagulation.

Chapter 8 131

Thrombocytopenia, decrease in platelet count. Purpura, is a group of bleeding disease due to
thrombocytopenia

Blood Coagulation

When blood oozes out of a cut, it sets into gel within a few minutes. This is called coagulation. Coagulation is brought about
by hydrolysis of soluble fibrinogen of plasma to insoluble fibrin. This is catalyzed by an enzyme called thrombin. Fibrin
precipitates as a network of fibres. This network traps many blood cells, particularly RBC's to form a red solid mass called
the Blood Clot. The clot seals the wound in the vessel to stop the bleeding. The straw-colored fluid left after clotting of
blood, is called Serum. The serum can not be coagulated as it lacks fibrinogen.

Thrombin occurs in normal blood as an inactive globulin called Prothrombin. It must be activated to thrombin before
blood coagulation can occur. In case of injury to a blood vessel, coagulation promoting substances called Thromboplastins
are released into the blood from clumped platelets and damaged tissues. Thromboplastins help in the formation of the
enzyme Prothrombinase. This enzyme hydrolyses prothrombin to thrombin to initiate coagulation. Ca2+ ions are essential
for both the activation and action of thrombin.

Blood normally contains an anticoagulant, Heparin which prevents activation of prothrombin, heparin is released from
mast-cell granules. Blood also contains Antithrombin which inhibits any thrombin formed accidentally.

Blood drawn from a blood vessel can be kept uncoagulated by adding a pinch of oxalate (sodium or potassium oxalate) to
it. Oxalate precitates Ca2+ and consequently prevents coagulation. Chilling of blood also delays coagulation because cold

cdepresses the action of coagulation promoting enzymes.

Blood Clotting Factors

These factors are designated by Roman numerals.
International Description
Nomenclature

Factor I Fibrinogen, soluble plasma protein, MW 3,30,000; plasma level 250-400 mg%.

Factor II Prothrombin, MW 69,000; plasma level 40 mg%.

Factor III Thromboplastin or tissue factor or tissue extract.
Factor IV
Ionic calcium. Removal of Ca2+ by potassium oxalate, sodium citrate or sodium edetate (EDTA, Versene)
prevents clotting in vitro.

Chapter 8 132

Factor V Labile factor or proaccelerin or accelerator globulin. It gets consumed during clotting and is,
therefore, absent from serum.

Factor VI Unidentified.

Factor VII Proconvertin or serum prothrombin convergen accelerator (SPCA) or stable factor or Autoprothrombin
I. Not consumed during clotting and, therefore, is present in serum as well as in plasma.

Factor VIII Antihemophilic factors (AHF) or Antihemophilic globulin (AHG) or antihemophilic factor-A (AHF-A).
It is consumed during clotting, therefore, absent from serum; half life 10-20 hours.

Factor IX Christmas factor or plasma thromboplastin component (PTC) or autoprothrombin II or AHF-B.

Factor x Stuart power factor or autoprothrombin-C. Present in plasma and serum.

Factor XI Plasma thromboplastin antecedent (PTA) or AHF-C. present in plasma and serum both.
Agglutination is due to the interaction of antigens and antibodies. There are two kinds of antigens that
are named A and B. There are also two kinds of antibodies which are called a and b. Then antigen A andFactor XIIHageman factor or glass factor or contact factor, present in plasma and serum both.

cantibody a are incompatible (antagonistic) and cause self clumping and cannot exist together. Thus A
Factor XIII Fibrin stabilizing factor or fibrinrase or Laki-Lorand factor. It causes polymerization of soluble fibrin to

produce insoluble fibrin

Blood Groups

ABO Blood Group Karl Landsteiner reported first time ABO blood groups in human
beings. A,B and O blood groups were discovered by Landsteiner (1900) while AB
blood group was found out by de Castello and Steini (1902). Aggluinogens
(=antigens) are present on the surface of red blood corpuscles and agglutinins
(=antibodies) are found in the blood plasma. Both antigens and antibodies are
proteins. When two different type of blood are mixed, the red blood corpuscles form
a clump. The clumping of red blood corpuscles is called agglutination.

and B can exist together and therefore, B and a can exist together. The corpuscles factor a and B can

occur together if their antagonistic plasma factors a and b are not present. The plasma factors a and b

can occur together if their antagonistic corpuscle factors A and B are absent.

Incompatibility during pregnancy : The incompatibility of blood groups of mother and foetus may cause
problems during pregnancy. For example, if the mother's blood group is A and the Foetus's blood group
is B, the antibodies b (plasma factor b) of the mother blood plasma attack and destroy same foetal red
blood corpuscles. This may cause anaemia, jaundice, etc. in the baby and is called haemolytic disease of
the new-born. It is a mild disorder and rarely needs blood transfusion

2. Muscular tissue:-
Muscle cause movements of limbs and internal organs and also locomotion of the organism. Cells of
muscle tissue can shorten forcefully and again return to the relaxed state. This specialized property is
called Contractility. It is based on the organized arrangement of some protein filaments in the

Chapter 8 133

cytoplasm of muscle cell. The cell shortens or relaxes according to the relative positions of dofferent
intracellular filaments. Whenever adequately stimulated, muscle cell respond by contracting. This
property of the muscle tissue is responsible for the various movements in an animal. Muscle cells are
usually called Muscle Fibres because they are thin and elongated. In higher animals, some muscles
remain associated with the skeleton, but many others form walls of visceral organs, blood vessels and
heart. Muscle tissue may be classified into striated, non-striated and cardiac muscles, according to their
structure, location and functions.

Striated/Skeleton/Voluntary muscles:-

c
Striated/Skeleton/Voluntary muscles are attached to bones by tendons. A voluntary muscle is
composed of long bundles of striated muscle fibres. Each fibre is long, unbranched, cylindrical cell. It
shows transverse striations in the form of regular alternate dark (A) and light (I) bands. At the centre of
I band is a fine, dense, dark band, the Z band or Z-line (Krause's membrane). The plasma membrane
covering the fibre is called Sarcolemma. The cytoplasm inside the fibre is called Sarcoplasm. The
sarcoplasm contains many long, thin, unbranched, cross-striated cylindrical structures called Myofibrils.
They are arranged along the long axis of the fibre. Dark A bands of neighbouring myofibrils are located
side by side, So also are their light I bands. This gives cross-striated appearence to the entire muscle
fibre also. A-band has both actin and myosin filaments. The portion of A-band, where actin filaments are
absent is called H-zone. Z-zone or Krauze membrane is a dark membrane which bisects I band or

Chapter 8 134

isotropic band.

Muscle is rich in proteins. Most of these protein occur as two types of filaments arranged longitudinally
in myofibrils. The thick filaments are made up of the protein Myosin. Myosin filaments are located
inside A bands. Thin filaments are most numerous. They are composed of the protein Actin. From a fine,
dense, dark Z band at the centre of each I band, actin filaments extend through the I band and encroach
between myosin filaments upto a considerable distance into the A band. Each segment of the myofibril
from one Z band to the next functions as a contractile unit and is called a Sarcomere.

Various parts of a sarcomere have a specific arrangement of actin and myosin filaments as given below.

I band - Has only actin filaments c
A band - Has both actin and myosin filaments
H band - Has only myosin filaments
Z line - A membrane to which actin filaments are attached on both the sides.

Chapter 8 135

Skeletal Muscle c

 Human body contains over 400 skeletal
muscles

 40-50% of total body weight

 Functions of skeletal muscle

 Force production for locomotion and
breathing

 Force production for postural support
 Heat production during cold stress

Structure of Skeletal Muscle:
Connective Tissue Covering

 Epimysium

 Surrounds entire muscle

 Perimysium

 Surrounds bundles of muscle fibers

 Fascicles

 Endomysium

 Surrounds individual muscle fibers

Chapter 8 136

Structure of Skeletal Muscle: c
Microstructure

 Sarcolemma

 Muscle cell membrane

 Myofibrils

 Threadlike strands within muscle fibers
 Actin (thin filament)

 Troponin
 Tropomyosin

 Myosin (thick filament)

Chapter 8 137

Structure of Skeletal Muscle: c
The Sarcomere

 Further divisions of myofibrils

 Z-line
 A-band
 I-band

 Within the sarcoplasm

 Sarcoplasmic reticulum

 Storage sites for calcium

 Transverse tubules
 Terminal cisternae

Chapter 8 138

c

Chapter 8 139

Muscular Contraction c

 The sliding filament model

 Muscle shortening occurs due to the
movement of the actin filament over the
myosin filament

 Formation of cross-bridges between actin
and myosin filaments

 Reduction in the distance between Z-lines
of the sarcomere

The Sliding Filament Model of
Muscle Contraction

Chapter 8 140

Cross-Bridge Formation in c
Muscle Contraction

Chapter 8 141

Sliding Filament Theory c

 Rest – uncharged ATP cross-bridge complex
 Excitation-coupling – charged ATP cross-

bridge complex, “turned on”
 Contraction – actomyosin – ATP > ADP & Pi

+ energy
 Recharging – reload cross-bridge with ATP
 Relaxation – cross-bridges “turned off”

Muscle Function

 All or none law – fiber contracts
completely or not at all

 Muscle strength gradation

 Multiple motor unit summation – more
motor units per unit of time

 Wave summation – vary frequency of
contraction of individual motor units

i. Non-Striated or Smooth muscle fibres do not
show cross-striations, instead, they look smooth.
Smooth muscles can not be moved voluntarily.
So they are also called Involuntary Muscles.
Functionally smooth muscles are of two types.
Single-Unit Smooth Muscles are composed of
muscle fibres closely joined together. All its

Chapter 8 142

fibres contract together as a single unit. They may contract
automatically and rhythmically. Such smooth muscles occur on
the walls of hollow visceral organs such as the urinary bladder and
the gastrointestinal tract. Multi-Unit Smooth Muscle are
composed of more independent muscle fibres, not so closely
joined together. Individual fibres of such smooth muscle contract
as separate unit. These occur at hair roots, and on the wall of
large blood vessels e.g., Erector pili muscles.

Smooth muscle fibres elongated spindle-shaped cells. They are
packed parallel to each other in branching bundles. Each fibre
contains a single, spindle shaped nucleus at its thick central part.
The smooth muscle fibre is generally shorten than a striated
muscle fibre. Mitochondria and other organelles are less
extensive and protein filaments are not regularly arranged to give
rise to striations.
c(i) They have number of muscle (i) They have number of muscle
Table IV : Differences between Single-unit and Multi-unit Smooth
Muscles

Single-unit smooth muscles Multi-unit smooth muscles

fibres closely joined together. fibres not so closely joined.

(ii) All the fibres contract together (ii) The individual fibres contract as
as a single unit, automatically. e.g., separate units more or less as
walls of hollow visceral organs like independent muscle fibre. e.g.,
stomach, intestine, urinary bladder hair roots, and on the walls of large
etc. blood vessels.

Chapter 8 143

i. Cardiac muscle occurs exclusively in the heart. It possesses
considerable automatic rhythmicity and generates its own wave
of excitation. The excitation can also pass directly from fibre to
fibre in the cardiac muscle. It is not under voluntary control. It
shows cross-striations, but striations are much fainter than those
of striated muscle. Between the cardiac fibres intercalated are
present. They are specialized regions of cell membrane of two
adjacent fibres. The intercalated discs function as boosters of
contraction wave and permit the wave of contraction to be
transmitted from one to another.

cCardiac muscle cells are short cylindrical cells joined end to end to

form rows. They possess abundant cytoplasm with myofibrils
(sarcoplasm) and numerous mitochondria and glycogen granules.

This is because they need a large amount of energy. Faint but
regular, alternate dark and light bands gives rise to cross-
striations in the cardiac muscle fibres and indicate regular and
alternate arrangements of thin and thick filaments in the fibre.
Sarcomeres are also present. Cardiac muscle cell frequently
branches to form junctions with neighbouring cells. Where two
cardiac muscle cells meet end to end, dense zig-zig junction is

Chapter 8 144

formed between them. It is called an Intercalated Disc. Long
refractory period is present in cardiac muscles.

Nerve Tissue

Ordinary connective tissue is absent inside the central nervous system, the neurons are held together by
supportive cells called Neuroglia Cells. Nerve tissue is made of neurons and neuroglia cells.

A Neuron has a large cell body with two or more, thin protoplasmic processes extending from it. One of
the prosses called the Axon is long and conducts nerve impulses away from the cell body. It ends in a
number of small branches on muscle fibres, gland cells or other neurons. The remaining one or more
prosses conduct nerve impulses towards the cell body and are called Dendrites or Dendrons. The axon
terminals may form inter-communicating junctions called Synapses, with dendrites terminals, cell
bodies or even axons of other neurons. Nerve impulses pass between neurons through the synapse with
the help of chemicals such as acetycholine which are termed Neurotransmitters.

The cell body of a neuron is called the Soma. The soma has various shapes. Both the soma and the
prosses are covered by the plasma membrane. The soma contains abundant granular cytoplasm and a
large nucleus. To serve the high energy needs for impulse conduction, neurons have many
mitochondria. Light microscopy shows many small conical, angular or rhomboidal and highly basophilic
structures in the cytoplasm of soma and dendrites, They are called Nissl Bodies and are absent in the
axon and the axon hiloock. Nissl's bodies are made up of ribosomes, ER, m-RNA.

The processes which are arise from neuron are called as neurites. These are of two types-Dendrites,
Axon.

i. Dendrites conduct the nerve impulse towards the nerve cell body and are called as afferent
processes.

ii. Axon is a single, usually long process. The part of cyton from where the axon arises is called as

caxon hillock. The cell membrane of the axon is called axolemma and its cytoplasm is known as

axoplasm. The axon divides to form axon ending; each with a synaptic knob. The synaptic knob
contain mitochondria and secretory vesicles. The vesicles contain neurotransmitter which is
nor-adrenaline or Acetyl chlorine.

Chapter 8 145

c

Chapter 8 146

Basic nerve cell structure

 Dendrite  Fine hair-like extensions on the end of a c
neuron.
 Function: receive incoming stimuli.

 Cell Body or Soma  The control center of the neuron.
 Function: Directs impulses from the dendrites to the
axon.

 Nucleus  Control center of the Soma.
 Function: Tells the soma what to do.

 Axon Pathway for the nerve impulse (electrical message)
from the soma to the opposite end of the neuron.

 Myelin Sheath  An insulating layer around an axon. Made
up of Schwann cells.

 Nodes of Ranvier  Gaps between schwann cells.
 Function: Saltatory Conduction (Situation where speed
of an impulse is greatly increased by the message
‘jumping’ the gaps in an axon).

Chapter 8 147

Types of Neurons

 There are 3 types of neurons.

1. Sensory Neurons  Neurons located near receptor
organs (skin, eyes, ears).

 Function: receive incoming stimuli from the
environment.

2. Motor Neurons  Neurons located near effectors
(muscles and glands)

 Function: Carry impules to effectors to initiate a
response.

3. Interneurons  Neurons that relay messages between
other neurons such as sensory and motor neurons. (found
most often in Brain and Spinal chord).

3 main types of nerve cells c

sensory relay motor
neurone neurone neurone

Chapter 8 148