Epithelium 1

Question 1

Characteristics of the epithelial cells

Answer 1

1. Composed of closely aggregated cels forming cellular sheets 2. Shapes: squamous, cuboidal, columnar
2. Adjacent epithelial cells are adhering by cellular junctions
   4.the basal surface rests on the basement membrane
   5.avascular
3. Receive nutrients from connective tissues
   7.lamina propria: lines the respiratory and urinary systems
4. Show polarity (basal and apical poles)
5. Papillae projected from connective tissue
6. Originate from embryonic layers
7. Have nerve fibers

Question 2

Principal function of the epithelial tissues

Answer 2

1. Protection: epidermis
2. Absorption: intestinal lining
   3.secretions: glands
3. Contractile: myoepithelium
4. Sensory: taste buds

Question 3

What is the basement membrane?

Answer 3

Its a thin extra cellular sheet of macromolecules between the basal surface of the epithelia and the underlying connective tissue

Question 4

What is the structure of the basement membrane?

Answer 4

Thin layer
Can be stained with PAS and silver
Secreted from the epithelial cells

Question 5

Basement membrane structure with the EM

Answer 5

1. Cell coat of the epithelial cells (appears as a light zone underneath the outer lamina of the plasma membrane
2. Basement membrane proper
3. Connective tissue rich in reticular fibers

Question 6

What is the basal lamina chemically composed of?

Answer 6

Glycoproteins and collagen
(PAS+ve when seen in the LM)

Question 7

What is the cell coat?

Answer 7

Oligosaccharide chains linked to lipid and protein molecules and extended outward from the plasma membrane forming the cells glycocalyx (cell coat)

Question 8

Functions of the basement membrane

Answer 8

1.Provides structural support for the epithelial cells
2.acts as a filter of diffusing macromolecule (kidney)
3. Maintains cell polarity
4. Permits the flow of nutrients
5. Controls epithelial growth and differentiation