Epithelia & renal

Question 1

tight junctions;

Answer 1

• connect two adjacent plasma membrane of difference cells. (DO NOT connect cytosols)
• separate apical and basolateral membrane sides(maintains polarity)
• determines the properties of hte paracellular pathway and constrains diffusion of solutes and fluids; leaky(proximal tubule, gate), or tight(collecting duct, barrier)

Question 2

Gap junctions

Answer 2

• connects cytoplasmic compartments of cells via connexins
• allows exchange of small molecules(mostly ions) between cells
• build electrical connections sometimes(e.g. conduction in the heart)

Question 3

Desmosome

Answer 3

• connects cells tightly via cadherins
• cadherins are connected to dense plaques that organise intra-cellular filaments(stabilisation)

Question 4

apical membrane

Answer 4

also called luminal, mucosal, or brush-border membrane
- faces the lumen of an organ(lungs, kidney, gut)
- contains microvilli in highly re-absorptive or secretory epithelial cells
- variable properties
- does NOT contain the Na+/K+ ATPase

Question 5

Basolateral membrane

Answer 5

also called serosal memnbrane
consists of basal membrane and lateral intercellular membrane
- faces the interstitial fluid
- more consistent than apical membranes- high water and K+ permeability
- expresses NA+/K+-ATPase
- does NOT contain microvilli, but does have membrane infoldings.

Question 6

Absorptive epithelia

Answer 6

• transport from mucosal to serosal side
• driven by Na+ transport
• (basolateral Na+/K+-ATPase creates a sodium gradient into the apical membrane.)

Question 7

Secretory epithelia

Answer 7

• transport from serosal to mucosal side
• secretion driven by Cl- transport

Question 8

‘normal’ vs. pathologic urine

Answer 8

Normal
looks;
- clear, light or dark amber look
taste;
- acidic (pH: 5-6)
(vegetarians up to 7.2 ,high protein diet, down to 4.8)
Smell;
unremarkable

Pathologic
look;
-golden, red, brown, blue
taste;
- sweet - diabetes mellitus
smell;
- fruity - ketosis(fasting), diabetes, chronic alcohol abuse.
- rotten; bacterial infection, tumour.