L2 - Epithelial Tissue

Question 1

What is the function of epithelial tissue?

Answer 1

Covers body surface
lines hollow organs, cavities and ducts
Forms the glands of the body

Question 2

What is the cytoskeleton composed of?

Answer 2

Microfilaments such as actin
Intermediate filaments such as keratin

Question 3

Describe the structure of tight junctions

Answer 3

Strands of transmembrane proteins (claudins and occludins) link adjacent plasma membranes in a ‘sew-like’ appearance

Question 4

What is the function of tight junctions

Answer 4

Joins the cytoskeleton of adjacent cells
Keeps cell polarity by preventing migration of proteins between apical and basal surfaces

Question 5

Where are tight junctions primarily found?

Answer 5

Stomach, intestines, bladder

Question 6

Describe the structure of adherens junction

Answer 6

Two plaques (patches of protein tissue) on each membrane linked together by cahderin
Cadherin links to catenins which links to actin

Question 7

What is the function of adherens junction

Answer 7

Links the microfilaments of adjacent cells preventing cell separation from tension forces like muscle contraction

Question 8

Describe the structure of desmosome junctions

Answer 8

Composed of two plaques joined together by cadherin
Cadherin spans the gap and binds to Desmoplakin which links to keratin

Question 9

Function of desmosome junctions

Answer 9

Links the intermediate filaments of adjacent cells providing strength to the junctions between cells
Allows tissue to resist shearing forces

Question 10

Where are desmosome junctions found

Answer 10

They bind muscle cells; most common in skin epithelium and cardiac cells of the heart

Question 11

Describe the structure of gap junctions

Answer 11

6 ConnexIn protein molecules to make a ConnexOn / hemichannel
2 hemichannels make up a gap junction

Question 12

Function of gap junctions

Answer 12

Allows cells to communicate with one another
Transfer of ions and small molecules between adjacent cells of tissue

Question 13

Describe the structure of hemidesmosomes

Answer 13

A plaque is connected to the basement membrane via Integrin Integrin acts as linker protein between keratin of the basal layer cell and laminin in the BM

Question 14

Function of hemidesmosomes?

Answer 14

Prevents movement of the epithelial layer over the basement membrane; fixation of cell

Question 15

What does the junctional complex include

Answer 15

Tight junction, Adherens junction, desmosome

Question 16

What is the function of the basement membrane?

Answer 16

Supports the overlying epithelium
Provides a surface along which epithelial cells migrate during growth and wound healing
Acts as a physical barrier
Participates in the filtration of substances in the kidney

Question 17

What are the two types of glandular epithelia?

Answer 17

Endocrine - secretes hormones into blood (more distant strong effects)
Exocrine - secretion onto external surfaces and ducts (more local effects)

Question 18

What is endothelium?

Answer 18

Simple squamous epithelium lining the inside of the heart, blood and lymphatic vessels (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM)

Question 19

What is mesothelium?

Answer 19

Simple squamous epithelium lining the serous membranes of the heart, lungs and abdominal areas

Question 20

What are examples of where simple squamous epithelium is found?

Answer 20

In Bowman’s capsule of kidney, cardiovascular
and lymphatic systems, inside eye, alveoli of lungs, visceral cavity linings, inside blood vessels and inside heart

Question 21

Where is simple cuboidal epithelium found?

Answer 21

Where there is SECRETION and ABSORPTION
Pancreas ducts, parts of kidney tubules, smaller ducts of many glands, secretory chambers of thyroid; anterior surface of lens; pigmented epithelium at posterior of retina; secretory part of some glands like thyroid

Question 22

What are microvilli

Answer 22

Finger-like projections from the membrane that increases surface area for absorption and exchange of materials

Question 23

What are cilia

Answer 23

Short hair-like projections from columnar epithelia cells that can act in a sweeping motion to move substances along surfaces

Question 24

Where is non-ciliated simple columnar epithelium found?

Answer 24

GI tract from stomach to anus, ducts of many glands, gallbladder

Question 25

Where is ciliated simple columnar epithelium found?

Answer 25

some bronchioles, uterine fallopian tubes, sinuses; central canal of spinal cord, ventricles of brain

Question 26

What are the features of keratinised stratified squamous epithelium?

Answer 26

Contains kertain making surface tough and waterproof Found in skin

Question 27

What are the features of non-keratinised stratified squamous epithelium?

Answer 27

Do not contain keratin therefore lines wet surfaces such as mouth, oesophagus, vagina, pharynx and tongue Moistened by mucous

Question 28

What are the features of pseudostratified columnar epithelium

Answer 28

All cells touch the basement membrane but not all cells reach the apical surface Can be ciliated or non-ciliated

Question 29

What is the difference between ciliated and non-ciliated pseudostratified columnar epithelia?

Answer 29

Ciliated has goblet cells Non-ciliated has no goblet cells Therefore ciliated lines most of upper airways and non-ciliated lines larger ducts of glands, epididymis, part of male urethra

Question 30

Where are ciliated pseudostratified columnar cells commonly found?

Answer 30

most of upper airways

Question 31

Where are non-ciliated pseudostratified columnar cells commonly found?

Answer 31

larger ducts of glands, epididymis, part of male urethra

Question 32

What are the features of stratified cuboidal epithelium?

Answer 32

Usually for protection - limited secretion and absorption Found in ducts of sweat glands and oesophageal glands

Question 33

What are the features of stratified columnar epithelium?

Answer 33

Proection and secretion Found in part of urethra, large excretory ducts of some glands, small areas in anal mucous membrane

Question 34

What are the features of transitional epithelium?

Answer 34

Looks like stratified cuboidal epithelium Outer layer is large, round (scallop shaped) when relaxed On stretching, outer layer become flat and squamous like Found in urinary bladder (only)

Question 35

Name the different shapes of multicellular ducts (8 total)

Answer 35

Simple tubular Simple coiled tubular Simple branched tubular Simple alveolar Simple branched alveolar Compound tubular Compound alveolar Compound tubuloalveolar

Question 36

Example of simple tubular glands

Answer 36

Intestinal glands

Question 37

Example of simple coiled tubular glands

Answer 37

Merocrine sweat glands

Question 38

Example of simple branched tubular glands

Answer 38

Gastric glands Mucous glands of oesophagus, tongue, duodenum

Question 39

Example of simple alveolar glands

Answer 39

A stage in the embryonic development of simple branched glands

Question 40

Example of simple branched alveolar glands

Answer 40

Sebacous (oil) glands in the skin

Question 41

Example of compound tubular glands

Answer 41

Mucous glands (in mouth) Bulbo-urethral glands (in male reproductive system) Seminiferous tubules of testes

Question 42

Example of compound alveolar glands

Answer 42

Mammary glands

Question 43

Example of compound tubuloalveolar glands

Answer 43

Salivary glands Glands of respiratory passages Pancreas