epithelia

Question 1

key functions of the basement membrane

Answer 1

supports the overlying epithelia
gives epithelial cells a surface for migration (e.g during wound healing)
is a physical barrier
important for kidney function/filtration
diffuses blood and nutrients through to epithelia from connective tissues

Question 2

explain the structure and function of a tight junction

Answer 2

strings of claudin and occludin protein ‘sew’ up the gap between cell membranes, preventing things (e.g ions and proteins) from entering or exiting the intercellular space

Question 3

nicknames/shapes for different lateral cell junctions

Answer 3

tight= sewing, gap = pizza, adherens= belt, desmosomes=button.

Question 4

explain the structure and function of an adherens junction

Answer 4

a plaque of proteins forms a belt on the cell membrane. cadherins span the gap between membranes and link to catenins, which lock cadherin to the microfilaments (actin) of the cytoskeleton.

prevent separation from tension forces like contraction.

Question 5

explain the structure and function of a desmosome

Answer 5

a plaque of proteins forms a button on the cell membrane. cadherins span the gap between cells and link to desmoplakins, linked to keratin intermediate filament of the adjacent cells.

prevents cells from separating due to shearing forces

Question 6

explain the structure and function of a gap junction

Answer 6

6 connexin proteins join to form a connexon/hemichannel, which dock electrically to one another and open a communication channel for controlled exchange of materials (e.g ions, RNA) and communication between cells.

Question 7

explain the structure and function of a hemidesmosome

Answer 7

hemidesmosome. keratin of the basal epithelial cell is linked by integrin protein to the laminin of the basement membrane. secures the epithelia down to the BM to prevent it sliding around.

Question 8

where might you find ciliated cells in the body and why

Answer 8

areas of tissue where movement across a surface is needed; e.g in the respiratory system for mucus, or uterine tubes for eggs.

Question 9

do simple, stratified, and pseudo stratified refer to the arrangement or shape of epithelial cells?

Answer 9

arrangement

Question 10

where are transitional epithelial cells found and why

Answer 10

in the bladder, as they can change from a cuboidal to squamous shape to allow flexibility for fluid level fluctuation

Question 11

functions of a simple squamous epithelium

Answer 11

filtration, diffusion, secretion

Question 12

what is the mesothelium; where is it found?

Answer 12

a type of simple squamous epithelium that lines visceral cavities( big sacs)
the peritoneum (abdomen), pleural (lungs), pericardium (heart).

Question 13

what is the endothelium; where is it found?

Answer 13

a type of simple squamous epithelium that lines the inside of the circulatory system; heart, blood/lymph vessels

Question 14

what is meant by serosa

Answer 14

a secretory tissue layer surrounding certain visceral cavities, consisting of a layer of mesothelium and connective tissue.

Question 15

what are goblet cells

Answer 15

specialised columnar cells which produce and secrete mucus

Question 16

why do goblet cells have more cytoplasm

Answer 16

because they’re more metabolically active

Question 17

what type of columnar cell doesn’t have goblet cells?

Answer 17

non-ciliated pseudostratified columnar epithelium

Question 18

stratified cuboidal epithelium function and location:

Answer 18

protection and secretion.
ducts of exocrine glands, (e.g eccrine sweat glands), male urethra.

Question 19

stratified columnar epithelium function and location

Answer 19

protection and secretion.
conjunctiva of the eye, urethra, ducts of large glands.

Question 20

non-ciliated pseudostratified columnar epithelium function and location

Answer 20

absroption and secretion.
epididymus, male urethra, larger ducts of glands

Question 21

what is the name of the sac that surrounds the heart

Answer 21

pericardium

Question 22

what is the name of the sac surrounding the abdominal cavity

Answer 22

peritoneum

Question 23

what is the name of the sac surrounding the lungs

Answer 23

pleural

Question 24

eccrine sweat glands are an example of: and are lined with:

Answer 24

an exocrine gland. stratified cuboidal epithelium.

Question 25

simple ciliated columnar epithelium function and location:

Answer 25

secretion and movement upper respiratory passages e.g bronchioles and sinuses (move mucus), uterine tube (move eggs into uterus), brain ventricles (move CSF)

Question 26

simple non-ciliated columnar epithelium function and location

Answer 26

absorption and secretion. gastrointestinal tract from stomach to anus, for absorption of nutrients (with microvilli) and secretion of digestive enzymes and mucus (goblet cells)

Question 27

simple cuboidal epithelium location and function

Answer 27

secretion and absorption. found in many places like organs, ducts, and parts of eye.

Question 28

stratified keratinised squamous epithelium function and location

Answer 28

protection. found in areas of dry mechanical stress/friction; skin.

Question 29

ciliated pseudostratified columnar epithelium function and location

Answer 29

secretion and movement. most of upper airways, e.g trachea.

Question 30

transitional stratified epithelium function and location

Answer 30

flexibility. bladder, for stretch during volume fluctuation. some also in ureters and urethra.

Question 31

what types of cells/tissues have cell junctions. where aren't they found?

Answer 31

mainly in tightly packed tissues like epithelia, muscle, and nervous tissue. free-moving cells like blood our immune cells may not have any.

Question 32

what epithelium facilitates rapid diffusion of nutrients and gases

Answer 32

simple squamous

Question 33

what epithelium provides a tough, waterproof barrier against dehydration

Answer 33

keratinised stratified squamous

Question 34

what epithelium allows stretching and recoil in hollow organs

Answer 34

stratified transitional

Question 35

what epithelium provides protection against stress/friction in wet areas

Answer 35

non-keratinised stratified squamous

Question 36

where do the layers of basement membrane come from, and what main molecules are in each?

Answer 36

basal lamina is secreted by epithelium. contains collagen, laminin, heparan sulphate. reticular lamina is secreted by connective tissue/fibroblasts. contains collagen, laminin, fibronectin, and reticular fibres (which is collagen III).

Question 37

why is epithelia important in kidneys?

Answer 37

selectively permeable for filtration

Question 38

stratified non-keratinised squamous epithelium function and location

Answer 38

protection. found in wet trauma areas prone to friction/stress; mouth, tongue, throat, oesophagus, anus, vagina.

Question 39

epithelial tissue covers:

Answer 39

body surfaces

Question 40

epithelial tissue lines:

Answer 40

hollow organs, body cavities, ducts

Question 41

what are other names adherens belts are known by?

Answer 41

zonula adheren, belt desmosome

Question 42

where are there lots of tight junctions and why?

Answer 42

stomach, bladder, intestines. provide watertight barriers regulating what passes between cells to prevent gut contents from leaking.

Question 43

what is another name for a tight junction

Answer 43

zona occluden

Question 44

is epithelium vascular and does it have nerve supply?

Answer 44

it is avascular but has nerves

Question 45

how does epithelium get its nutrients

Answer 45

they diffuse up from the connective tissue, through the basement membrane

Question 46

what does the brush border refer to

Answer 46

microvilli

Question 47

how do endocrine glands perform secretion

Answer 47

they secrete substances directly into the blood via traversing the interstitial fluid

Question 48

how do exocrine glands perform secretion

Answer 48

they secrete substances onto a surface, or more often into a duct which empties onto a surface

Question 49

outline the difference and relationship between mucous cells, single-cell exocrine glands, and goblet cells

Answer 49

mucous cells are any cell that secretes mucous. these are sometimes, but not always, single-cell exocrine glands. single-cell exocrine glands are unicellular exocrine glands. goblet cells are a specific type of mucous cell named after their goblet shape.

Question 50

in what instances might glandular epithelia be the producer of what it secretes

Answer 50

in some endocrine glands, like in the thyroid

Question 51

what type of cell junction allows for polarity and how

Answer 51

tight junctions by sealing off the membrane near the apical, creating distinct apical and basolateral regions with different compositions

Question 52

where would you not find a hemidesmosome

Answer 52

anywhere except at the basal surface of epithelial cells; hemidesmosomes are specific to epithelium as they connect basal cells to the basement membrane