Chapter 4 Notes_ Tissues

Anatomy & Physiology 

Chapter 4 Notes: Tissues 

I. Tissues:​ collections of cells and cell products that perform 
specific, limited functions. 

A) Histology​:​ The study of t​ issues 

Four types of tissues 
1. Epithelial 
2. Connective 
3. Muscle 

4. Neural 
 

1. Epithelial Tissue 

● Covers body surfaces 
● Lines cavities  
● Lines tubular structures  
● Serves essential functions 
 
a) Characteristics of Epithelial Tissue 
- Cellularity (cell j​ unctions: Things that hold cells together)​  
- Polarity (a​ pical​ and ​basal ​surfaces) 
- Attachment  
- Avascularity: Without blood supply/vessels 
- Regeneration 
 
b) Functions of Epithelia 
- Provide physical protection 
- Control p​ ermeability: Ability to allow fluid/moisture through 
- Provide sensation 
-  Produce specialized secretions (​glandular epithelium)​  

Exocrine ​glands 
Endocrine​ glands 

 

 

c) The Epithelial Surface 
Apical s​ urface​ is exposed 

● Basal​ surface is connected to deeper connective tissue with the 
basement membrane 

 

 

 
 

d) Epithelial Renewal and Repair 
● Epithelia are replaced by ​mitosis.  
● Cell division of stem c​ ells​ (g​ erminative cells​) 
● Occurs near b​ asement membrane 

 

 
e) Classification of Epithelia 

● Combines a cell shape with the number of layers of cells 
Example: Simple (one layer) cuboidal (square shape) 

 

II. Cell Layers and Cell Shapes 

Classification ​based on layers 

• Simple epithelium​: single layer of cells 
• Stratified epithelium​: several layers of cells 

Classification ​based on shape 

• Squamous epithelia​: thin and flat 
• Cuboidal epithelia:​ square shaped 
• Columnar epithelia:​ tall, slender rectangles 
 

 

a) Glandular Epithelia 

Endocrine glands 
● Release hormones​ ​into interstitial fluid and plasma 

● No ducts 

Exocrine glands 

● Produce secretions: 
● Onto epithelial surfaces 
● Through ducts  

 

b) Glandular Secretion 

● Merocrine secretion 
Released by vesicles (e​ xocytosis)​   

Example: sweat glands 

● Apocrine secretion 
Released by shedding cytoplasm 

Example: mammary glands 

● Holocrine secretion 
Released by cells bursting, killing gland cells 
Example: sebaceous glands 
 

 

​ Types of Secretion 

Serous glands 
watery secretions 

Mucous glands 
Secrete mucins 

Mixed exocrine glands 
Both serous and mucous 

 

III. Connective Tissue 

Function:​ Provides a protective structural framework for other tissue types 

 
Three basic components 

1. Specialized cells 
2. Solid extracellular protein​ f​ ibers 
3. Fluid extracellular​ ​ground substance 

 

Characteristics of Connective Tissue 

● The extracellular components of connective tissues (fibers and ground 
substance) make up the matrix.​  

● Majority of tissue volume 
● Determines specialized function 
 

Functions of Connective Tissue 

● Support and protection. 
● Transportation of materials 
● Storage of energy reserves 
● Defense of the body 

 
Three Major Types of C​ onnective Tissue 

1. Connective tissue proper 
2. Fluid connective tissues 
3. Supporting connective tissues 

 
a) Cells of Connective Tissue Proper 
● Fibroblasts: Produces collagen and other fibers 

• Most abundant​ cells in connective tissue proper 
• Produce connective tissue fibers and ground substance 

● Macrophages: White blood cells that eat debris and 
“bad guys” 

- Scattered throughout the matrix 
- Phagocytize d​ amaged cells or pathogens that enter the 

tissue 
- Release chemicals that mobilize the immune system 

● Fat cells (a​ dipocytes)​  
- Permanent residents 
- Number of fat cells vary 

● Mast cells 
- Small, mobile cells often found near blood vessels 
- Filled with chemicals that are released to begin body's 

defensive activities after an injury or infection 

Three Basic Types of Connective Tissue F​ IBERS 

1. Collagen fibers  
● Long, straight, unbranched 
● Strong, but flexible 
● Most common 

2. Elastic fibers 
● Branched and wavy 
● After stretching, they will return to their original   
length 
● Contain the protein ​elastin 

3​ .​ Reticular fibers 
● Made of same protein subunits as collagen fibers, but 

arranged differently 
● Thinner than collagen fibers 
● Form branching, interwoven framework in various 

organs 
● Least common 

 

Ground Substance 

● Clear, colorless, and v​ iscous 
● Fills spaces between cells and slows bacterial and ​pathogen 
movement 

 

A. Types of Connective Tissue 
Proper 

● Loose connective tissue 

- "Packing materials" of the 
body 

- More ground substance, fewer 
fibers 

E​ xample: fat (​adipose tissue)​  
 

● Dense connective 
tissue 
- Tough, strong, and 
durable 
- More fibers, less 
ground substance 
E​ xample: 

Tendons 

 

 
 
 

B. Fluid Connective Tissues 

● Blood​ and lymph 
Watery matrix of dissolved proteins 

● Red blood cells   
● White blood cells  
● Platelets 
 

c. Supporting Connective Tissues 

● Cartilage  
Gel-type ground substance 
For shock absorption and protection 

● Bone  
Calcified (made rigid by calcium salts, minerals) 
For weight support 

 

 

1. Cartilage 

● Cartilage matrix 
Ground substance proteins  

● Chondrocytes​ (cartilage cells)  
Surrounded by ​lacunae​ (chambers) 

 

​Cartilage Structure 

● Avascular 
- Chondrocytes found in pockets  
called lacunae 

● Perichondrium 
- Outer, fibrous layer (for strength) 
- Inner, cellular layer (for growth and 

maintenance) 

 

 
Three Major Types of Cartilage 

a. Hyaline cartilage 
- Stiff, flexible support 
- Reduces friction between bones 
- Found in synovial joints, rib tips, sternum, and trachea 

b.​ E​ lastic cartilage 
- Supportive but bends easily 
- Found in external ear and epiglottis (area in the throat) 

c. Fibrocartilage 
- Limits movement 
- Prevents bone-to-bone contact 
- Pads knee joints 
- Found between pubic bones and intervertebral discs 

 

2. Bone (o​ sseous tissue) 

- Strong (hard calcium compounds)  
- Resists shattering (flexible collagen fibers) 
● Bone cells or o​ steocytes 
- Arranged around central canals within matrix 
- Small channels through matrix (c​ analiculi)​ access blood supply 

 
 
 

3. Tissue Membranes 

Membranes are: 
• Are physical barriers  
• Line or cover portions of the body 
• Consist of an epithelium  
• Supported by connective tissues 
 

Four Types of Tissue Membranes 

1. Mucous membranes 2. Serous membranes 

3. Cutaneous membrane 4. Synovial membranes

 
 
 
 
 
 

1. Mucous Membranes (aka​ ​mucosae) 

- Lines passageways that have external connections  
- In digestive, respiratory, urinary, and reproductive tracts 
- Epithelial surfaces must be moist 
- To reduce friction 
- To facilitate absorption and excretion  
- Made of areolar tissue (this portion is called l​ amina propria)​  
 

2. Serous Membranes 

- Line cavities not open to the outside 
- Are thin but strong 
- Have fluid transudate to reduce friction 
- Have a parietal portion covering the cavity 
- Have a visceral portion (serosa) covering the organs 
 

Three Serous Membranes 

a. Pleura 
- Lines pleural cavities 
- Covers lungs 

b. Peritoneum 
- Lines peritoneal cavity  
- Covers abdominal organs 

c. Pericardium 
- Lines pericardial cavity 
- Covers heart 

3. The Cutaneous Membrane (skin) 

- Covers the surface of the body 
- Thick, waterproof, and dry 
 

4. Synovial Membranes 

- Line moving, articulating joint cavities 
- Produce ​synovial fluid​ (lubricant) 
- Protect the ends of bones 
- Lack a true epithelium 
 

IV. Three Types of Muscle Tissue 

1. Skeletal muscle tissue 

- Large body muscles responsible for movement 

2. Cardiac muscle tissue 

- Found only in the heart 

3.​ Smooth muscle tissue 

- Found in walls of blood vessels 
- Found around hollow organs such as the urinary bladder 
- Around the respiratory, digestive, and reproductive tracts 

 

a. Functions of Muscle Tissue 

- Specialized for contraction 
- Produces all body movement 

 

V. Neural Tissue (AKA nervous​ or ​nerve tissue) 

- Specialized for conducting electrical impulses  
- Rapidly senses internal or external environment 
- Processes information and controls responses 

● Concentrated in the central nervous system 
- Brain 

  - Spinal cord 

 

Two Kinds of Neural Cells 

1. Neurons 

• Nerve cells  
• Perform electrical communication 

2. Neuroglia 

• Supporting cells 
• Repair and supply nutrients to neurons 

 
 
 
 
 
 

Cell Parts of a Neuron 

● Cell body 
- Contains the nucleus and nucleolus 

● Dendrites 
- Short branches extending from the cell body 
- Receive incoming signals 

● Axon ​(nerve fiber) 
- Long, thin extensions of the cell body 
- Carries outgoing electrical signals to their destination 

VI. Tissue Injuries and Repair 

● Tissues respond to injuries to maintain homeostasis 

- Cells restore homeostasis with two processes 
1. Inflammation 
2. Regeneration 

 

Inflammation 
● Inflammatory response 
The tissue's first response to injury 

Signs and symptoms include: 

Swelling Redness 

Heat  Pain 

● Can be triggered by: 

-Trauma (physical injury) 

- Infection (the presence of harmful pathogens) 

Aging and Tissue Structure 
● With age the rate of tissue repair declines and the rate of cancer 
increases 

● Speed and efficiency of tissue repair decrease with age due to: 

- Slower rate of energy consumption (metabolism) 
- Hormonal alterations 
- Reduced physical activity 

Aging and Cancer Incidence 

- 1 in 4 people in the United States develops cancer 
- Cancer is the #2 cause of death in the United States 
- Environmental chemicals and cigarette smoke cause cancer