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Animal Tissues
A group of differentiated and specialised cells.
Histology – The study of tissues and their structure.
Epithelial Tissue
Form the covering of all body surfaces, line body cavities and hollow organs.
Arranged in continuous sheets of one or more layers.
Always one free surface where no other cells adhere to it.
Basement Membrane – Strong non-cellular layer made up of collagen fibres
which the bottom layer is attached to.
Remain meristematic as they are subjected to wear and tear and therefore need to
produce cells to replace those worn away.
Do not contain blood vessels.
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Squamous (Pavement) Epithelium
Found in: Mouth, oesophagus, lining of blood vessels, alveoli of the lungs.
Structure:
Single layer of thin, flattened cells (friction free)
Irregular shape and closely packed in a mosaic form.
Nucleus is centrally located forming a ‘bump’ in the surface.
Cells attached to the basement membrane.
Functions:
Ideal surface for diffusion of gasses (e.g. lungs and capillaries).
Smooth surface provides a friction-free lining for blood to flow.
Protects and gives support to underlying tissues.
Cuboidal Epithelium
Glands and other structures with a secretory function- thyroid gland, liver and kidney
tubules.
Structure:
Closely packed cube shaped cells.
No spaces between the cells.
Cells attached to the basement membrane.
Function:
Usually a secretory function.
Columnar Epithelium
Lines the stomach, small intestine and part of the respiratory tract.
Structure:
Tall, elongated, column shaped and longer than they are wide.
Elongated nucleus found near the base of the cell.
Attached to a basement membrane.
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Functions:
Absorption of food.
Protects and supports underlying tissue.
Ciliated Epithelium
Found in moist surroundings and lines the nostrils, trachea, bronchi, oviducts and sperm
ducts.
Structure:
Comprises columnar epithelial cells with cilia at the free edges.
Functions:
The combination of mucus and wave-like movements of cilia permits substances to be
moved through ducts.
In the respiratory tracts, dust particles are moved forward and expelled to protect the lungs
from harm.
Movements of ova and sperm in the carrying ducts are due to cilia.
Helps with the movement of fluids along the central canal of the spinal cord.
Glandular Epithelium
Unicellular Glandular Epithelium
Found in the small intestine and respiratory passages.
Structure:
Consists of columnar or cuboidal epithelial.
Consist of a single, isolated glandular cell (called goblet cells) which are scattered amongst
non-glandular cells.
Goblet Cell – Modified epithelial cells that secrete mucus on the surface of mucous
membranes of intestines for facilitation of movement and respiratory passage to
keep it slimy & moist.
Multicellular Glandular Epithelium
Animal Tissues
A group of differentiated and specialised cells.
Histology – The study of tissues and their structure.
Epithelial Tissue
Form the covering of all body surfaces, line body cavities and hollow organs.
Arranged in continuous sheets of one or more layers.
Always one free surface where no other cells adhere to it.
Basement Membrane – Strong non-cellular layer made up of collagen fibres
which the bottom layer is attached to.
Remain meristematic as they are subjected to wear and tear and therefore need to
produce cells to replace those worn away.
Do not contain blood vessels.
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Squamous (Pavement) Epithelium
Found in: Mouth, oesophagus, lining of blood vessels, alveoli of the lungs.
Structure:
Single layer of thin, flattened cells (friction free)
Irregular shape and closely packed in a mosaic form.
Nucleus is centrally located forming a ‘bump’ in the surface.
Cells attached to the basement membrane.
Functions:
Ideal surface for diffusion of gasses (e.g. lungs and capillaries).
Smooth surface provides a friction-free lining for blood to flow.
Protects and gives support to underlying tissues.
Cuboidal Epithelium
Glands and other structures with a secretory function- thyroid gland, liver and kidney
tubules.
Structure:
Closely packed cube shaped cells.
No spaces between the cells.
Cells attached to the basement membrane.
Function:
Usually a secretory function.
Columnar Epithelium
Lines the stomach, small intestine and part of the respiratory tract.
Structure:
Tall, elongated, column shaped and longer than they are wide.
Elongated nucleus found near the base of the cell.
Attached to a basement membrane.
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Functions:
Absorption of food.
Protects and supports underlying tissue.
Ciliated Epithelium
Found in moist surroundings and lines the nostrils, trachea, bronchi, oviducts and sperm
ducts.
Structure:
Comprises columnar epithelial cells with cilia at the free edges.
Functions:
The combination of mucus and wave-like movements of cilia permits substances to be
moved through ducts.
In the respiratory tracts, dust particles are moved forward and expelled to protect the lungs
from harm.
Movements of ova and sperm in the carrying ducts are due to cilia.
Helps with the movement of fluids along the central canal of the spinal cord.
Glandular Epithelium
Unicellular Glandular Epithelium
Found in the small intestine and respiratory passages.
Structure:
Consists of columnar or cuboidal epithelial.
Consist of a single, isolated glandular cell (called goblet cells) which are scattered amongst
non-glandular cells.
Goblet Cell – Modified epithelial cells that secrete mucus on the surface of mucous
membranes of intestines for facilitation of movement and respiratory passage to
keep it slimy & moist.
Multicellular Glandular Epithelium
