2. cont TO CELL, TISSUES, MEMBRANE

NERVOUS TISSUE

✓ It stimulates muscle contraction, creates an awareness of the
environment, and plays a major role in emotions, memory, and
reasoning.

✓ Two types of tissue are found in nervous system:
1. Excitable cells – these are called neurons and they initiate, receive,

conduct and transmit information.
2. Non excitable cells – known as glial cells and support the neurons.



TISSUE REGENERATION

There are 3 general categories:

1. Tissue in which cell replication is a continuous process regenerate
quickly; ex: skin, mucous membrane, secretory glands, uterine lining
and reticular tissue.

2. Other tissue retain the ability to replicate but infrequently, these
include the liver, kidney fibroblast and smooth muscle cells. Take
longer to regenerate.

3. Some cells unable to replicate, include nerve cells (neuron), skeletal
and cardiac muscle cells – damaged tissue cannot be replaced.

MEMBRANES

Mucous Membrane

✓ -moist lining of the alimentary, respiratory and genitourinary tracts –
known mucosa.

✓ -membrane surface consist of epithelial cells, produce mucus, slimy,
tenacious fluid.

✓ -mucus protects the lining membrane from drying, and from
mechanical/ chemical injury.

✓ Ex: in the respiratory tract trap inhaled particles, preventing from
entering the alveoli of the lungs.

Serous Membrane

There are 3 sites where serous membrane are found:
1. The pleura lining the thoracic and cavity surrounding the lungs
2. The pericardium lining the pericardial cavity and surrounding the

heart.
3. The peritoneum lining the abdominal cavity and surrounding

abdominal organs.
Ex: the heart changes its shape and size during each beat, and friction
damage prevented by the arrangement of pericardium serous fluid.

Synovial Membrane

✓ -lines the cavity of moveable joints
and tendons that could be injured
by rubbing against bones e.g over
the wrist joint.

✓ -clear, sticky, oily synovial fluid,
which lubricates and nourish the
joints.

Glands Exocrine Glands Endocrine Glands

Characteristics

Definition Exocrine glands are the glands Endocrine glands are the
Ducts with ducts that allow the cells to glands that do not have a
secrete their products into those duct system and release
ducts so that they can be their secretions or
released onto the surface of the hormones directly into the
target cells or organs. bloodstream.

Endocrine glands are

Exocrine glands have one or more ductless glands that

ducts that transport their release the hormones

secretions. directly into the

bloodstream.

Glands

Characteristics Exocrine Glands Endocrine Glands

Secretions The secretions of exocrine glands The secretions of endocrine
Target site are enzymes, mucins, ions, water, glands are hormones.
etc.

The target sites of the gland are The target sites of the endocrine
located close to the exocrine gland. glands are present away from
the gland.

Response Exocrine glands usually show rapid Endocrine glands exhibit
response as the secretions are delayed response as the
released directly into the target secretions need to be
organs. transported to the site of action.

Glands Characteristics Exocrine Glands Endocrine Glands

Types Exocrine glands can be differentiated Endocrine glands are of
Function into different types like unicellular and three distinct types;
multicellular exocrine glands, trabecular type, follicular
merocrine, apocrine and holocrine type, and disseminated type.
glands, etc.

Exocrine glands monitor the short- Endocrine glands control the
term activities and functions of the overall structure, growth, and
target organs. development of the target
organs.

Examples Some examples of exocrine glands Some examples of endocrine
include the sweat gland, liver, glands are the adrenal gland,
pancreatic acini, salivary glands, pituitary gland,
mammary glands, etc. ovaries, thyroid gland, etc.