Epithelia and Glands

Question 1

5 types of contact points between plasma mmbranes of tissue cells - connections

Answer 1

• tight junctions
• adherens junctions
  -desmosomes
  -hemidesmosomes
• gap junctions

Question 2

tight junctions

Answer 2

web like strands of transmembrane proteins, which encircle the membranes.
seals off passegways between adjacen cells and imparis passage of substances between the cells or leakage into blood or surrounding tissue

Question 3

adherens junctions

Answer 3

forms a dense layer of protins called a plaque. located inside the plasma membrane attached to bothmembrane proteins and microfilaments of the cytoskeleton. transmembrane glycoproteins called cadherins insert into the plaque and join cells.
- resists seperation of cells during contractions

Question 4

desmosomes

Answer 4

• plaque and cadherins that extend into the intercelullar space
• plaque attahced to intermediate filaments that contain keratin
  -preveent seperation under tension and cardiac muscles during contrcaction

Question 5

hemidesmosomes

Answer 5

-resemble half a desmosome
- do not link adjacnet cells but anchor to basement membrane
-transmembrane glycoprotein integrin, attahces to intermediate filaments and protein laminin in basement membrane

Question 6

gap junctions

Answer 6

connect cells via tiny fluid filled tunnels called connexons
- very narrow intercellualr gap between adjacent membranes
- allowsfor ion, nutrient, waste, to travel from cell to cell
- for communication of cells within a tissue

Question 7

3 types of surfaces of epithelia

Answer 7

• apical : face body cavitity, lumen, duct
• lateral surface facing adjacent cells
• basal surface: opposite of apical,

Question 8

2 layers making up the basement membrane

Answer 8

basal lamina: top layer in contact with cells, secreted by epithelial cells, laminin, collagen, glycoproteins

reticular lamina: closer to underlying connective tissue, collagen secreted by connective tissue

Question 9

do epithelia have blood vessels?

Answer 9

no they are avascular, blood vessels in underlying connective tissue provide nutrients and eliminate waste

Question 10

outer covering of skin and some internal organs is called

Answer 10

covering and lining epithelium

Question 11

the secreting portion of glands is called what type of epithelium

Answer 11

glandular epithelium

Question 12

3 types of layers of epithelia- arrangemenft of cells in layers

Answer 12

simple- 1 layer, diffusion, osmosis, filtration, secretion and absorption

pseudostratified- appear as more than 1 due nuclei at different levels, but 1 layer

stratified- 2 or more layers, protect underlying tissue in areas of wear and tear

Question 13

4 shapes of epithelia

Answer 13

squamous- thin, arranged like floor tiles, rapid passage of substances
cuboidal: cubes or hexagons, may have microvilli, secretion and absorption
columnar: may ahev cilia or microvilli, secretion and absorption
transitional: transition from flat to cuboidal, to stretch and collapse

Question 14

types of simple epithelia

Answer 14

simple squamous
simple cuboidal
simple columar (ciliated and non ciliated)
pseudostratified columnar

Question 15

simple squamous

Answer 15

flattened oval or sphere, cetral nucleus, filtration and diffusion, found in lung, renal capsules

make up the covering anfd lining epithelia:
endothelium: lines heart, blood vessels, lymphvessels
mesothelium: pericardium, pleura or peritoneum

Question 16

simple cuboidal

Answer 16

central nuclei
thyroid gland, kidney tubules
secretion and absorption

Question 17

non ciliated simple columnar

Answer 17

oval nuclei near the base
microvilli at apical surface and goblet cells
mucus used as lubricant in digestve, rspiratory, reproductive and urinary tracts. prevents destruction of lining by acid

Question 18

ciliated simple columnar

Answer 18

cilia on apical surface
may have goblet cells
moves mucus by ciliary action
bronchioles, uterus and falopian tubes, ducts of testes

Question 19

pseudostratified columnar

Answer 19

not all reach apical surface
can have ciliated, non ciliated and golet cells

Question 20

types of stratified epithelia

Answer 20

stratified squamous
stratified cuboidal
stratified columnar
transitional

Question 21

stratified squamous

Answer 21

• new cells pushed towards they surface
• as they lose blood supply they dehydrate, harden and die
• found in mouth and oesophegus, vaginal canal: non keratinized
  found in skin- keratinized

Question 22

stratified cuboidal and stratified columnar

Answer 22

rare and for protection
columnar for secretions as well

Question 23

transitional

Answer 23

relaxed state- cuboidal, upon stretching they flatten and become squamous
for hollow structure subject to expansion

Question 24

exocrine vs endocrine

Answer 24

exocrine have ducts and secrete onto body surface directly, endocrine are ductless and release hormones into circulation

Question 25

3 types of glands

Answer 25

endocrine- acts on distant cells
autocrine- cells of smae secreting gland
paracrine: do not reach circulation but act locally on cells of same tissue

Question 26

exocrine glands have 3 types of release mechanisms

Answer 26

merocrine - release by exocytosis, fusion of vesicles to apical surface

apocrine- release of contents by pinching off part of the cell therefore surrounded y cytoplasm and membrane. mammary glands, ciliary lands of eyelid

holocrine- products accumulate in maturing cell, cell undergoes apoptosis and discharges products and cell debris into lumen, sebacous glands of skin

Question 27

classification of multicellular glands,

Answer 27

they form tubular invaginations made up of 2 parts:

Secretory Portion shape
- TUBULAR: straight, branched or coiled
- ACINAR/ALVEOLAR: rounded: single or branched
- TUBULOALVEOLAR : tubular and rounded.

Duct branching:
branched—compound
non branched—simple

Question 28

exocrine glands that empty into internal surfaces also release what?

Answer 28

mucous or serous secretion

Question 29

mucous vs serous secretions

Answer 29

mucus: thick and viscous, salivary glands, glycosylated proteins, mucinogenic granules lost in tissue prep leading to cytoplsasm on mucous cells appearing empty on staining

serous: watery, non glycosylated proetins, cells have cytoplasm that stains intensly with eosin

Question 30

integumentary system

Answer 30

skin and its accessory structures
skin: epidermis, dermis and hypodermis

Question 31

cells of the epidermis

Answer 31

keratinized stratified squamous epithelium with keratinocytes,
melanocytes (melanin producing cells absorb UV light),
langerhans cells (dendritic cells with Birbeck granules, antigen presenting cells)
merkel cells (contact tactile disc of sensory neurons,, for sensation of touch- mechanotransduction)

Question 32

layers of the epidermis

Answer 32

Stratum basale - deepest layer of cuboidal/columnar cells, melanocytes, langerhans

Stratum Spinosum: layer above basal layer, keratinocytes take a flatter appearance,

Stratum Granulosum: middles layer of keratinocytes undergoing apoptosis, keratohyalin granules, lamellar granules

Stratum Lucidum: only in very thick skin like palms and soles, pale staining, dying keratinocytes contain a lot of keratin but have not been completely replaced by it

Stratum Corneum: consistenly shed off and replaced, dead flat squame keratinocytes and densly packed intermediate filaments and keratohyalin

Question 33

the dermis composition and layers

Answer 33

typical connective tissue
2 regions: superfiical papillary dermis and deeper reticular dermis

Question 34

papillary dermis

Answer 34

loose areolar connective tissue with collagen and elastin
dermal papillae - finger like projections- have capillaries
freenerve endings

Question 35

reticular dermis

Answer 35

dense irregular coarse collagen fibres and thick elastic fibres interspersed with fibroblasts, blood vessels and nerves,,
sweat and sebacous glands