Lecture 8(unit2)- Epithelia & Membranes

Question 1

Principal functions of epithelial tissues

Answer 1

-Control permeability
-Protection
-Specialized secretions
-Sensation
•Neuroepithelia (special senses)

Question 2

Characteristics of epithelial tissues (SPARCS)

Answer 2

• Specialized connections
• Polarity
• Avascular
• Regeneration
• Cellularity
• Supported (by a Connective Tissue)

Question 3

Specialized attachments

Answer 3

• Tight junction
• Desmosome
• Hemidesmosome

Question 4

What forms a membrane?

Answer 4

• Epithelia

- Connective Tissue

Question 5

Each membrane consists of ?

Answer 5

• Sheet of epithelial cells

- An underlying Areolar connective tissue (other Connective tissues layers may be present but deeper)

Question 6

Serous membranes

Answer 6

-line the ventral body cavities (the peritoneal, pleural, and pericardial cavities)

Question 7

Mucous membranes

Answer 7

• are coated with the secretions of mucous glands

- line most of the digestive and respiratory tracts and portions of the urinary and reproductive tracts

Question 8

Synovial membranes

Answer 8

• line joint cavities and produce the fluid within the joint

Question 9

Cutaneous membrane

Answer 9

• the skin

- covers the outer surface of the body

Question 10

Myoepithelial cells

Answer 10

• Its contractile function helps to expel secretions from the Lumina of the secretory units and ducts. Supporting functions are: The structure of myoepithelial cell is similar to that of smooth muscle.
• usually found in glandular epithelium as a thin layer above the basement membrane but generally beneath the luminal cells.

Question 11

Neuroepithelia

Answer 11

-Neuroepithelial cells are the stem cells of the central nervous system, known as neural stem cells, and generate the intermediate progenitor cells known as radial glial cells, that differentiate into neurons and glia in the process of neurogenesis.

Question 12

Exocrine glands

Answer 12

• Discharge their secretions onto the surface of the skin onto an epithelial surface lining.
• Ex: Enzymes entering the digestive tract, perspiration on the skin, and the milk produced by mammary glands.

Question 13

Serous glands

Answer 13

-Secrete a watery solution that usually contains enzymes, such as the salivary amylase in saliva.

Question 14

Mucous Glands

Answer 14

-Secrete glycoproteins called mucins that absorb water to form a slippery mucus, such as the mucus in saliva.

Question 15

Mixed exocrine glands

Answer 15

-Contain more than one type of gland cell and may produce two different exocrine secretions, one serous and the other mucous.

Question 16

Two types of unicellular glands and where are they found?

Answer 16

• Goblet cells, found in Columnar Epithelium of the small and large intestine
• Mucous cells, found in pseudostratified ciliated Columnar Epithelium that lines the trachea

Question 17

Merocrine secretion

Answer 17

-The secretory product, packaged into secretory vesicles, is released through exocytosis onto the surface of the cell.
-Most common mode of secretion.
•Ex: Release of saliva from serous cells in the salivary gland, or mucins from goblet cells in the intestine.

Question 18

Apocrine secretion

Answer 18

-the secretory product is released during the shedding of the apical portion of the cell’s cytoplasm, which has become packed with secretory vesicles.
-The cells then undergo regrowth and produce additional secretory vesicles.
•Ex: Lactiferous cells of the mammary glands.

Question 19

Holocrine secretion

Answer 19

-Holocrine secretion destroys the gland cell.
-During the secretion m, the entire cell becomes packed with secretory products and then bursts apart. The secretion is released and the cell dies.
-Further secretion depends on gland cells being replaced by the division of the stem cells found deeper within the Epithelium.
•Ex: Sebaceous gland cells

Question 20

Endocrine glands

Answer 20

• release their secretion by exocytosis from the gland cells into the fluid surrounding cell.
• These secretions, called hormones, diffuse into the blood for distribution to other regions of the body, where they regulate or coordinate the activities of various tissues, organs, and organ systems.