Epithelial Cells & Tissues

Question 1

properties of tissue

Answer 1

group/s of cells whose type, organisation + architecture are integral to function

cells, ECM + fluid

Question 2

what is the extracellular matrix

Answer 2

material deposited by cells - “insoluble” part of extracellular environment

fibrillar proteins embedded in hydrated gel

may be poorly or highly organised

Question 3

what are the 5 main cell types

Answer 3

connective tissue
contractile tissue
haematopoietic
neural
epithelial

Question 4

types of tumors (6)

Answer 4

carcinomas - epithelial
sarcomas - mesenchymal (connective tissue and muscle)
leukaemias - haematopoietic
lymphomas - lymphomas
neuroblastomas - neurones
gliomas - glial

Question 5

epithelial functions

Answer 5

transport, absorption, secretion, protection

Question 6

two main criteria of epithelial classification

Answer 6

shape (squamous, cuboidal, columnar)
layering (simple, stratified, pseudostratified)

Question 7

simple squamous epithelium + 3 examples

Answer 7

form thin epithelium that allows exchange to occur

e.g
lung alveolar (air sac) epithelium
mesothelium (lining major body cavities)
endothelium lining blood vessels and other blood spaces

Question 8

simple cuboidal epithelium + 1 example

Answer 8

mainly in linings of ducts

e.g lining the kidney collecting ducts

Question 9

simple columnar epithelium + 1 example

Answer 9

surfaces involved in absorption and secretion of molecules

e.g enterocytes lining the gut

Question 10

keritinizing vs non-keritinizing

Answer 10

keratinizing epithelium form thick layers that protect underlying tissues for various physical and chemical insults

e.g. heat, cold, solvents (alcohol), abrasion, etc

no nuclei visible in surface cell layers in keritinizing epithelium

Question 11

keritinizing stratified squamous epithelium + 1 example

Answer 11

produce keratin + die = thicker, stronger + protective
lose cellular organelles and nuclei
not visible under light microscopy

e.g epidermis

Question 12

non-keritinizing stratified squamous epithelium + 5 examples

Answer 12

do not undergo keratinisation
retain nuclei + organelles

e.g. epithelium lining the mouth, oesophagus, anus, cervix and vagina

Question 13

pseudo-stratified epithelium + 2 examples

Answer 13

appears to be multi-layered but surface cells all have contact with basal lamina

e.g.
airway (trachea and bronchi) epithelium
various ducts in the urinary and reproductive tracts

Question 14

methods used by solutes to cross membranes

Answer 14

gases + hydrophobic molecules = diffuse across the lipid bilayer

most molecules = passive/active using proteins

Question 15

what is cell polarisation

Answer 15

when cell organelles + membrane proteins are organised to give the cell directionality

Question 16

absorptive epithelium

Answer 16

apical:
brush border + cells arranged as villi = more SA
BB = active transporters and channels = more uptake
many mitochondria

baso:
passive transport

(absorb things into bloodstream e.g intestinal brush border absorbs nutrients)

Question 17

secretory epithelium - exocrine

Answer 17

secretion into a duct or lumen
organelles are arranged for secretion from the apical plasma membrane

Question 18

secretory epithelium - endocrine

Answer 18

into the bloodstream
secrete their contents to the basal aspect
vesicles positioned so contents have close access to blood circulation

Question 19

epithelial cell proliferation

Answer 19

constant replacement of lost cells by proliferation of stem cells
balance between proliferation + death is key to maintaining tissues

Question 20

example of too little proliferation

Answer 20

e.g inhibition of stem cell proliferation in intestinal crypts due to chemotherapy leading to gastro-intestinal disturbances

Question 21

example to too much proliferation

Answer 21

leads to overproduction of tissue as rate of cell loss isn’t sufficient to maintain normal tissue volume
benign tumours such as adenomas can form - high risk of mutation into malignant

Question 22

proliferation at epidermis

Answer 22

cells of basal layer of stratified squamous epithelia divide + migrate up to replace cells lost from surface

while migrating - undergo differentiation that leads to flattening + keratinising

Question 23

hyperproliferation of epithelia of epidermis

Answer 23

increased cell numbers + thickening of cell layers

Question 24

what can cause hyperproliferation of epithelia of epidermis

Answer 24

continuous or repeated pressure + abrasion
infectious agents such as papilloma virus (hijack cell machinery + induce increased proliferation e.g warts)

Question 25

cell turnover summary

Answer 25

cell loss = cell production ==> steady state

cell loss > cell production ==> reduction in tissue mass

cell loss < cell production ==> increased tissue mass