Molecular Biology - Epithelial cells/tissues

Question 1

System hierarchy

Answer 1

Cells - tissues- organs - organ systems - organism

Question 2

Tissue

Answer 2

Group or groups of cells whose type, organisation and architecture are integral to its function

Question 3

Extracellular matrix

Answer 3

Material deposited by cells which forms the insoluble part of the extracellular environment - composed of fibrillar proteins embedded in hydrated gel

Question 4

Epithelial cells

Answer 4

Form continuous layers which line ad separate tissue compartments

Question 5

5 main cell types

Answer 5

Connective tissue cells - chrondocytes etc
Contractile tissue - cardiac/skeletal muscle
Haematopoietic cells - blood cells
Neural cells - neurones and glial cells (support)
Epithelial cells

Question 6

Carcinomas

Answer 6

Derived from epithelial cells

Question 7

Sarcomas

Answer 7

Connective tissue/muscle cancers

Question 8

Leukaemias (bone marrow) /lymphomas (lymphocytes)

Answer 8

Haematopoietic cancers

Question 9

Neuroblastomas

Answer 9

Neural cell cancers from neurones

Question 10

Epithelial cells

Answer 10

Make organised/stable cell-cell junctions to form continuous and cohesive layers

Question 11

Epithelial layers

Answer 11

Cell-cell junctions are key to the formation and maintenance of epithelial layers

Question 12

Epithelial classification

Answer 12

Shape
Layer

Question 13

Shape

Answer 13

Squamous (plate shapes) - flat
Columnar - arranged in columns (long vertically)
Cuboidal - cube like

Question 14

Layer

Answer 14

Single layer = simple epithelium (alveoli)
Multi-layer = stratified epithelium

Question 15

Simple squamous found in

Answer 15

Small diffusion distance - alveoli/mesothelium/endothelium ; allows exchange to occur

Question 16

Simple cuboidal found in

Answer 16

Linings found in ducts

Question 17

Simple columnar epithelium

Answer 17

Surfaces involved in absoprtion and secretion of molecules (like enterocytes lining the gut)

Question 18

Keratinizing

Answer 18

Epithelial cells produce keratin - die - become thicker and stronger (like the skin) ; lose their cellular organelles

Question 19

Non-keratinizing

Answer 19

Retain their nuclei and organelles (epithelium lining mouth, anus etc)

Question 20

If no nuclei visible

Answer 20

Keratinizing

Question 21

purpose of keratinizing

Answer 21

Protects tissues from heat/cold/solvents etc

Question 22

Pseudo-stratified epithelium

Answer 22

Surface layers have contact with basal lamina

Question 23

Stratified means

Answer 23

NO GAP BETWEEN LAYERS OF CELLS

Question 24

Epithelial cells functions

Answer 24

Transporting epithelium
Absorptive epithelium
Secretory epithelium

Question 25

Membrane polarity gives

Answer 25

DIRECTIONALITY

Question 26

Bottom and top of cell

Answer 26

Bottom = basolateral (attached to basal lamina) Top = apical domain

Question 27

State of epithelia

Answer 27

Must be polarised for mass flow to occur

Question 28

Adaptations for efficient transport

Answer 28

Mnay mitochondria provide a lot of ATP needed for transport across membranes Greater membrane infoldings = larger surface area to pump

Question 29

Where are mitochondria located?

Answer 29

Near the basal aspect close to the infoldings which contain active transporters - apex has directionality (passive movement)

Question 30

Where is active transport confined mainly?

Answer 30

Basal - so ion/water transport has directionality

Question 31

Absorptive epithelium

Answer 31

Small intestine SA is long + greater with villi etc - found at brush-border membranes

Question 32

Brush borders

Answer 32

Rich in active transporters and channels for uptake of nutrients

Question 33

Secretory epithelium

Answer 33

Tubules + glands Exocrine (into duct/lumen) and ENDOCRINE (into bloodstream)

Question 34

Exocrine pancreas

Answer 34

Out via pancreatic duct

Question 35

Endocrine cells secrete tooooo

Answer 35

Basal aspect ; secretory vesicles are positioned for easy access to blood circulation

Question 36

Apical phase

Answer 36

Enzymes/pancreatic juices exocrine UNLIKE HORMONE BASAL

Question 37

Turning over of cells?

Answer 37

Cells lost by cell death and are replaced by proliferation of stem cells in epithelium ; balance between cell proliferation and cell death

Question 38

How does replacement work in turnover of epithelial cells?

Answer 38

Cells in intestinal crypts replace cells lost from tips of the villi?

Question 39

Cancer drugs what happens?

Answer 39

Drugs inhibit proliferation of crypt cells so = loss of villi and results in GI side-effects SHORTENED VILLI

Question 40

Tumour formation

Answer 40

Rate of cell loss not sufficient to maintain tissue volume - creates a benign tumour (adenoma) which has high risk of acquiring mutations that switch to cancerous

Question 41

Epithelial cell proliferation - epidermis

Answer 41

Proliferate in basal cell layer - lose their organelles and then migrate to surface (keratinising while doing so)

Question 42

Hyperproliferation of epithelial cells

Answer 42

Increased cell numbers and thickening ; cells will accumulate and create an increased thick hard layer

Question 43

Papilloma virus

Answer 43

Hijacks cellular machiner and induce proliferation which causes surface growth

Question 44

Changes to steady state physiologically?

Answer 44

Endometrial epithelial lining during menstrual cycle Increase during pregnancy in number and size of epithelial glands of breast