Epithelia & Secretion

Question 1

What structure do epithelial cells rest on?

Answer 1

Basement membrane

Question 2

Are epithelia innervated? Do they have a blood supply?

Answer 2

No they are avascular and not innervated

Question 3

What is the function of epithelia? What 3 things are they involved in?

Answer 3

They form barriers for:

1. Protection - skin
2. Absorption - gut
3. Secretion - glands

Question 4

What are the 4 main types of epithelia?

Answer 4

• Simple
• Stratified
• Pseudo-stratified
• Transitional

Question 5

Where can simple epithelia be found?

Answer 5

(Single layer of cells) in lungs

Question 6

Where can stratified epithelia be found?

Answer 6

(Multiple layers of cells) in skin

Question 7

Where can pseudo-stratified epithelia be found?

Answer 7

(Mixture of tall and short cells, looks stratified but single layer) in trachea

Question 8

Where can transitional epithelia be found?

Answer 8

(When released only bottom cells in contact with BM, when stretched all cells flatten) in bladder

Question 9

What type of epithelia lines the alveoli of the lung? What is the arrangement of cells in this epithelia? What is the shape and orientation of the cells nucleus? How does its structure relate to its function?

Answer 9

• Simple squamous epithelia
• Single layer of flattened cells
• Parallel, oval nucleus
• Provides a thin barrier for gas exchange to allow rapid diffusion of gases into/out of blood

Question 10

What type of epithelia lines the kidney tubules? What is the arrangement of cells in this epithelia? What is the shape and orientation of the cells nucleus? How does its structure relate to its function?

Answer 10

• Simple cuboidal epithelia
• Single layer of cuboidal cells
• Central, round nucleus
• Provides a large surface area for absorption of substances from the urine back into the blood

Question 11

What type of epithelia lines the respiratory airways? What is the arrangement of cells in this epithelia? What is the shape and orientation of the cells nucleus? How does its structure relate to its function?

Answer 11

• Simple columnar epithelia
• Single layer of columnar cells
• Perpendicular, oval nucleus
• Cells have cilia on apical surface to waft mucus up to throat to be swallowed

Question 12

What are microvilli? Where are they found? How does their structure relate to their function?

Answer 12

• Regular, finger-like projections on the apical surface of absorptive cells
• Found on cells lining the intestinal tract
• They greatly increase the surface area through which absorption can occur

Question 13

What are cilia? Where are they found? How does their structure relate to their function?

Answer 13

• Regular, motile appendages on apical surface of cells in respiratory tract or female uterine tubes
• Found on cells in respiratory tract and female uterine tubes
• They have filaments that actively beat to waft mucus or egg along the tract

Question 14

In what type of areas are stratified epithelia found in?

Answer 14

Areas where there is constant abrasion

Question 15

Features of stratified/compound epithelia

Answer 15

• Protective function
• Composed of many layers of cells
• Continually being worn down
• Worn away cells replaced from below

Question 16

What are the subtypes of stratified/compound epithelia?

Answer 16

Squamous, cuboidal

Question 17

What type of epithelia lines the oesophagus/vagina? What is the arrangement of cells in this epithelia? How does its structure relate to its function?

Answer 17

• Stratified squamous non-keratinised epithelia
• Many layers of flattened cells
• Many layers of cells help to protect against damage from constant abrasion the tissue is subject to

Question 18

What type of epithelia lines the skin? What is the arrangement of cells in this epithelia? How does its structure relate to its function?

Answer 18

• Stratified squamous keratinised epithelia
• Many layers of flattened cells
• Outer cells are no longer alive and are packed full of the protein keratin which makes our skin waterproof

Question 19

Where can stratified cuboidal epithelia be found?

Answer 19

In large ducts

Question 20

Is the epithelia in mouth keratinised or non-keratinised?

Answer 20

Non-keratinised

Question 21

What is the basement membrane composed of?

Answer 21

Collagen IV and fibronectin

Question 22

What kind of stain are basement membranes positive for?

Answer 22

Periodic Acid Schiff’s (PAS) stain
detects polysaccharides such as glycogen, and mucosubstances such as glycoproteins, glycolipids and mucins in tissues. Magenta colour

Question 23

What does the basement membrane separate?

Answer 23

Epithelium and connective tissues

Question 24

What type of gland secretes through ducts?

Answer 24

Exocrine

Question 25

What type of gland secretes without ducts?

Answer 25

Endocrine

Question 26

What is an example of a single cell gland? What is its function?

Answer 26

Goblet cell - Secretes mucus in respiratory tract to trap bacteria, which his then wafted up to the throat by cilia and swallowed

Question 27

What is an example of multicellular gland?

Answer 27

Pancreas

Question 28

What are the 2 types of glands? What do they each secrete? Give an example for each type

Answer 28

1. Mucous gland - secretes mucous - Sublingual gland | 2. Serous gland - secretes proteins e.g. enzymes - Parotid gland

Question 29

Differences between mucous and serous glands

Answer 29

Mucous glands: mucous, pale, round nuclei | Serous glands: proteins, darker, flat nuclei

Question 30

Which type of gland has flat nuclei?

Answer 30

Serous glands

Question 31

What is a mixed gland?

Answer 31

A gland that secretes both mucous and proteins e.g. mandibular gland