Lecture 4

Question 1

Apical surface of epithelium

Answer 1

Faces external environment/lumen. Involved in surface modifications that contribute to cell function. Plasma membrane contain specialised array of proteins and carbs (unique to each epithelium and function), transporters and channels (amino acid transporters in small intestine and ion channels/pump in kidneys)

Question 2

microvilli

Answer 2

Small finger-like projections that increase SA for increasing absorption rate. Appear in EM but brush boarder in LMC. Has actin core that ends in terminal web.

Question 3

stereocilia

Answer 3

Long immotile microvilli. Look like hairs from paintbrush. Found in male genital tract involved in absorption and in ear. Has sensory receptors

Question 4

microvilli vs stereocilia

Answer 4

Similarities: actin core
Differences: SC long, MV bruh boarder

Question 5

cilia

Answer 5

long. Has tubulin centre. Motile cellular processes ‘beat’. Seen in LM as paintbrush hairs. Basal bodies (tubulin anchors). core of tubulin arranged in axoneme. Uses ATP to move. Dyenein arms on side of doublet facilitates movement

Question 6

Axoneme

Answer 6

9x doublets of tubulin + 2x1 tubulin molecules (9+2 arrangement)

Question 7

Basal region

Answer 7

Attach epithelium to underlying CT. Has hemidesmosomes, focal adhesions and pedicles. Membrane folds to increase adhesion either between cells or betweel basal lamina and cells.

Question 8

Hemidesmosomes

Answer 8

Half a desmosome, 1 plaque. Anchors intermediate filaments of skeleton into basal lamina (rather than other cells). Common in sites with high mechanical stress.

Question 9

Focal adhesions

Answer 9

Anchor actin filaments to basal lamina. Formed by integrins and linking proteins. Involved in cell migration.

Question 10

Pedicles

Answer 10

Small irregular cytoplasmic projections. Increases SA. Hold cells into basal lamina.

Question 11

basal infoldings

Answer 11

increase SA for transport proteins and channels. Mitochondria typically located in folds. Energy required for active transport processes. Mitochondria go where lots of energy needed therefore, lots of active transport against conc. gradient. Lots of active transporters.