Epithelial Tissue

Question 1

Epithelium

Answer 1

Covers the body and lines cavities, hollow organs and tubes.
Protects underlying structures from damage
Secretion and absorption
Cells are very closely packed. Usually lie on a basement membrane which is inert connective tissue made by the epithelial cells themselves

Question 2

Simple epithelium

Answer 2

A single layer of identical cells, divided into 3 main types. Found on absorptive or secretory surface. The more active the tissue, the taller the cells.

Question 3

Squamous epithelium

Answer 3

A single layer of flattened cells forming a thin and very smooth membrane across which diffusion occurs easily.
Forms the lining of heart (called endocardium) blood and lymph vessels (endothelium) the alveoli of the lungs and the collecting ducts of nephrons in the kidneys

Question 4

Cuboidal epithelium

Answer 4

Cube-shaped cells fitting closely together and lying on a basement membrane.
Forms the walls of kidney tubules and is found in some glands such as the thyroid. Actively involved in secretion, absorption and/or excretion.

Question 5

Columnar epithelium

Answer 5

Single layer of tall thin cells on a basement membrane. Lines the stomach. Lines the small intestine whilst covered with microvilli. In the trachea, columnar epithelium is ciliated and contains goblet cells which secrete mucus.

Question 6

Stratified epithelium

Answer 6

Several layers of cells of various shapes. Continual cell division in the lower layers pushes above cells nearer to the surface where they are shed, basement membranes are usually absent.
Protect underlying structures from mechanical near and tear.

Question 7

Stratified squamous epithelium

Answer 7

Several layers of cells. In the deepest layers the cells are mainly columnar. As they grow towards the surface they become flattened and then are shed.
Keratinised stratified epithelium is found on skin, hair and nails.
Non-keratinised stratified epithelium protects moist surfaces subject to wear and tear and prevents them from drying out. Conjunctiva of the eyes, lining of the mouth, the pharynx, the oesophagus and the vagina.

Question 8

Transitional epithelium

Answer 8

Several layers of pear-shaped cells. Lines several parts of the urinary tract, including the bladder, allowing for stretch as the bladder fills.