Epithelia

Question 1

Key functions of epithelia

Answer 1

Selective barriers
Secretory
Protection

Question 2

Cell junctions

Answer 2

Tight junction
Desmosome
Hemidesmosome
Adherens junction
Gap junction

Question 3

What are intermediate filaments made of

Answer 3

Keratin

Question 4

What are microfilaments made of

Answer 4

Actin

Question 5

Function of cytoskeleton

Answer 5

Strength, alter cell shape; link cytoplasm to membrane; tie cells together; muscle contraction

Question 6

Features of tight junctions

Answer 6

Transmembrane sealing strands
Claudins and occludins key proteins
Join to actin and bind cytoskeletons of adjacent cells together
Electrically tight

Question 7

Features of adherens junctions

Answer 7

More basal than tight junctions
Plaque layer of proteins on inside of cell
Cadherins span gap
Cadherins linked to actin by catenins

Question 8

Function of adherens junction

Answer 8

Prevent separation of cells during contraction

Question 9

Where do desmosome junctions occur

Answer 9

Lateral walls

Question 10

Function of desmosomes

Answer 10

Resist shearing forces

e.g in cardiac muscle and epidermis

Question 11

Features of desmosomes

Answer 11

Cadherins span gap

Cadherins attach to keratin which stretches across cell to desmosome on other side

Question 12

Function of gap junctions

Answer 12

Direct connection between cells
Allow diffusion of material (1kDa)
Allow electrical signalling

Question 13

Features of gap junctions

Answer 13

6 connexin proteins form a connexon/hemichannel

2 connexons form a gap junction

Question 14

Function of hemidesmosome

Answer 14

Anchor basal surface to basement membrane

Question 15

Features of hemidesmosomes

Answer 15

Integrin as transmembrane protein

Attaches to keratin in the cytoplasm and laminin in the basement membrane

Question 16

Two structures of the basement membrane

Answer 16

Basal lamina

Reticular lamina

Question 17

Formation and contents of basal lamina

Answer 17

Secreted by epithelial cells
Laminins
Collagen
Proteoglycans
Glycoproteins

Question 18

Formation and contents of reticular lamina

Answer 18

Secreted by firoblasts

Fibrous proteins e.g fibronectin and collagen

Question 19

Function of basement membrane

Answer 19

Support of overlying epithelium
Acts as surface along which cells can migrate during growth or healing
Filtration in kidneys

Question 20

Cancer vs basement membrane

Answer 20

If a carcinoma pierces the basement membrane, chances of metastasis increase

Question 21

ABCD of cancerous mole

Answer 21

Asymmetry
Border irregularity
Colour
Diametre

Question 22

Types of epithelial tissue

Answer 22

Glandular

Lining/covering

Question 23

Arrangements of epithelium and explanation

Answer 23

Simple - Single layer (absorption/secretion)
Stratified - multiple layers (protection)
Pseudostratified - Appears to have multiple layers (secretion)

Question 24

Shapes of epithelium and general function

Answer 24

Squamous - diffusion
Cuboidal - Secretion/absorption
Columnar - Secretion/absorption
Transitional - Allow stretch

Question 25

Features, appearance, and function of simple squamous epithelium

Answer 25

Most delicate Irregular shaped, like a jigsaw Filtration, secretion, diffusion

Question 26

Special subtypes of simple squamous

Answer 26

Mesothelium - Lining of pericardial, pleural, and peritoneal cavities Endothelium - Inside lining of blood and lymphatic vessels

Question 27

Location of simple squamous

Answer 27

Bowman's capsule Cardiovascular and lymphatic systems Alveoli Visceral cavity linings

Question 28

Feature of simple cuboidal

Answer 28

Secretion and absorption | Appear as hexagonal or cuboidal boxes

Question 29

Location of simple cuboidal

Answer 29

``` Pancreatic ducts Parts of kidney tubules Smaller ducts Secretion chambers of thyroid Eyes ```

Question 30

Features and appearance of simple cuboidal epithelium

Answer 30

Larger cytoplasm, so more organelles Rectangular Elongated nucleus near base of cell

Question 31

Two major subtypes of columnar epithelium

Answer 31

Ciliated | Non-ciliated

Question 32

Features and location of non-ciliated simple columnar epithelium

Answer 32

Microvili on apical surface Goblet cells present Found in gastrointestinal tract and gall bladder

Question 33

Function of non-ciliated simple columnar epithelium

Answer 33

Secretion Lubrication Absorption

Question 34

Function of ciliated simple columnar epithelium

Answer 34

Synchronous movement helps move foreign matter

Question 35

Features and location of ciliated columnar epithelium

Answer 35

Also have goblet cells | Found in bronchioles, Fallopian tubes, sinuses, central canal of spinal cord and ventricles of brain

Question 36

Features and function of stratified squamous epithelium

Answer 36

Located at areas of high mechanical stress Protects against microbes Lower layers may be cuboidal while higher layers are flat

Question 37

Subtypes of stratified squamous epithelium

Answer 37

Keratinised - skin | Non-keratinised - mouth, throat, tongue, anus oesophagus, vagina

Question 38

Features of pseudo stratified columnar epithelium

Answer 38

Not all cells reach apical surface Nuclei at different levels Can be ciliated or non-ciliated

Question 39

Function and location of ciliated pseudo stratified columnar epithelium

Answer 39

Goblet cells present Secrete and move mucus Found in respiratory tract

Question 40

Function and location of non-ciliated pseudo stratified columnar epithelium

Answer 40

No goblet cells Absorption and secretion Found in epididymis and part of male urethra

Question 41

Function and location of stratified cuboidal

Answer 41

Rare | Found in ducts of adult sweat glands, esophageal glands, and part of male urethra

Question 42

Function and location of stratified columnar epithelium

Answer 42

Uncommon Only apical layer is columnar - basal layer short and irregular Lines urethra, some esophageal glands, large excretory ducts and conjunctiva

Question 43

Function and location of transitional epithelium

Answer 43

Variable shape -Unstretched = stratified cuboidal -Stretched = stratified squamous Ideal for lining hollow surfaces as it can stretch without rupturing Lines bladder and portions of ureter and urethra

Question 44

Endocrine gland function and examples

Answer 44

Secrete directly into interstitial fluid Pineal gland Thyroid gland Pituitary gland

Question 45

Exocrine gland function and examples

Answer 45

``` Secrete onto surfaces or lining epithelium Sweat glands Salivary glands Sebaceous glands Pancreas ```

Question 46

Different gland structures

Answer 46

``` Tubular Acinar Simple Coiled Compound ```