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Question 1

What happens in the glomerulus?

Answer 1

Plasma is filtered through itLarge proteins cannot be filtered but small ions can 20% is filtered whilst 80% remains in the blood

Question 2

What happens in the proximal convoluted tubule?

Answer 2

Reabsorbs about 67% of ions as well as water– has isosmotic reabsorption

Question 3

What is isosmotic reabsorption?

Answer 3

The concentrations of ions is the same at the start and the end of the PCT

Question 4

What ion transporters are found in the PCT?

Answer 4

Na-H antiporter Na-glucose symporter

Question 5

What is glomerulotubular balance?

Answer 5

The glomerular filtration rate and the reabsorption in the proximal convoluted tubule are matched– always have 67% of Na conc absorbed

Question 6

Describe the myogenic response

Answer 6

Afferent arteriole dilatation or constriction to control the flow of blood entering the kidneys so that it will always stay similar.

Question 7

What myogenic response occurs with an increased BP?

Answer 7

Afferent arteriole constriction

Question 8

What myogenic response occurs with a decreased blood pressure?

Answer 8

Afferent arteriole dilatation

Question 9

What is the main ion that controls the reabsorption of water?

Answer 9

Sodiumwhich is coupled to chloride movement – it is always assumed that chloride ions will be moving with Na in order to maintain electroneutrality.

Question 10

What is the effective circulating volume?

Answer 10

The volume of arterial blood effectively perfusing the tissue.

Question 11

How do chlorine molecules move?Where are most of the chlorine molecules reabsorbed?

Answer 11

Can be: transcellular and active paracellular and passive60% reabsorbed in the proximal convoluted tubule.

Question 12

What ion channels are found in the loop of henle?

Answer 12

NaKCC2 symporter

Question 13

What ion channels are found in the early distal tubule?

Answer 13

NaCl symporter

Question 14

What ion channels are found in the later part of the distal tubule?

Answer 14

ENaC (epithelial Na channels)

Question 15

What ion channels are found in the collecting duct?

Answer 15

ENaC (epithelial Na channels)

Question 16

Describe the ion movements that take place in the early PCT

Answer 16

Na uptake is high – is governed by oncotic and hydrostatic forcesCl is not being transported across, so there is a proportional increase in the amount of chloride ions present as H2O is leaving too.

Question 17

How is Na taken up in the PCT?

Answer 17

Is co-transported with glucoseNa-H exchangeCo-transport with AA/Carboxylic acidsCo-transport with phosphateAquaporin

Question 18

What ion movements occur in the latter part of the PCT?

Answer 18

Mostly Cl is reabsorbed passively due to electrochemical gradient from Na reabsorption as well as some being transported transcellularly using ATP.

Question 19

What are some driving forces behind water reabsorption?

Answer 19

1. Osmotic gradient established by the solute reabsorption2. Increased hydrostatic forces in the interstitium3. Increased oncotic force in the peritubular capillary due to the loss of 20% of filtrate

Question 20

Give some characteristics of reabsorption in the loop of henle?

Answer 20

Ascending and descending limb have different tubular cells so have different adaptations for the absorption of different ions.

Question 21

What reabsorption takes place at the descending limb?

Answer 21

Absorbs water but not NaClHas lots of aquaporin channelsH2O follows osmotic gradient.

Question 22

What reabsorption takes place at the ascending limb?

Answer 22

Absorbs NaCl but not water. Has tight junctions beween cellsNaCl is reabsorbed by NaKCC2 and Na is moved into the interstitium by Na/K/ATPase. ROMK allows K to leak back into lumen (v. important)

Question 23

What ion channel do loop diuretics target?

Answer 23

NaKCC2

Question 24

When is the myogenic response activated?

Answer 24

When there are momentary fluctuations – only used in the short term

Question 25

What happens at the distal convoluted tubule?How is it controlled?

Answer 25

Reabsorption here depends on the needs of the body. ADH secretion determines water reabsorption.