Kidney 2

Question 1

What is a nephron

what happens there?

Answer 1

Nephron = functional unit
Filtration under pressure

renal blod flow
Valuable substances begin to be reabsorbed in PCT

Question 2

What determine which solutes pass through into nephron

Answer 2

filtration barrier restricts solute movement based on size and change

Question 3

WHat is GRF=?

What detemines Glomerular filtration rate?

Answer 3

125ml/min= RF

Renal blood flow , which = 1.25 litre/min, there a mechansisms in place to maintain renal blood flow

Question 4

What happens in the proximal tubule?

Answer 4

70% of water is reabsorbed and solutes

Question 5

What structure is present on the PCtubule?

2) What is reabsorbed and in what form?
3) what else does it do?

Answer 5

microvilli

2) bulk of filtered NaCL as isotonic NaCl solition
3) blood secretes organic molecules into tubules like penincillin, bile salts, noradrenaline and and involved in pH homeostasis

Question 6

NcCl uptake is closely linked to:

Answer 6

uptake o essential solutes e.g. glucose, aa

regulation of body fluid pH

Question 7

Apical Na+ transport couple to:

Answer 7

1. co-transport of glucose or aa

2. counter-exchange of H+

Question 8

In loop of Henle what happens in descending limb

Answer 8

• H2O moves out

- NaCl stays

Question 9

In loop of Henle what happens in thick ascending limb

Answer 9

Thick Ascending Limb NaCl moves out
H2O stays
Na+-K+ ATPase
K+ channels, Na+-H+ exchanger (Na+ in , H+ out),

Question 10

What happens in distal convoluted tubule?

Answer 10

-NaCl moves out -H2O stays

Question 11

What happens in Collecting duct?

Answer 11

Collecting duct

• NaCl moves out
• H2O reabsorption depends on ADH (next lecture)
• H+ and HCO3- movement

Question 12

WHat are the 2 cell types in the Collecting duct?

Answer 12

prinicipal cells- have Na+ transporters

Intercalated cells- H+ transport involved in pH

Question 13

How is hypertension treated, how does it work?

what else effects this cahnnels

Answer 13

1. amiloride, inhibites ENaCC, a Na+ reabsorbed in the collecting duct
   aldosterone

Question 14

What is the osmolarity o plasma?
What percentage must its concentration be kept in?
3) How is it controlled?

Answer 14

Plasma kept within 1% of of 290 mosm/l

3) Brought about by alterations in WATER content of urine

Question 15

Glomerular filtrate can have the same osmolarity as the plasma BUT sometimes excretion of an isosmotic urine is not desirable.
Excretion of dilute or concentrated urine is achieved by the____________.

Answer 15

Countercurrent Mechanism

Question 16

Describe urine compared to plasma afer

1) H2O load
2) H2O restriction

Answer 16

After H2O load: H2O must be excreted in excess of solute in a dilute urine that is hyposomotic to plasma

After H2O restriction: H2O must be retained and a hyperosmotic or concentrated urine must be excreted

Question 17

1) The function of the loop of Henle is:

2) How is the countercurrent multiplier achieved?

Answer 17

to remove NaCl more than H2O from the lumen and deposit in interstitium
2) 2 parallel limbs with fluid flowing inopposite directions- countercurrent flow,
Active NaCl transport from ascending limb into interstitium, therefore osmality of intersticium increases, descending limb is permeable to water but not NaCl, therefore water exits descending limb, this then repeats,

Question 18

Compare osmarity in the descending limb compared to end of ascenidng limb:

Answer 18

ascending limb has a lower osmolarity, as NaCl has left, descending limb has a higher osmalrity as water has left

Question 19

What is the NaCl pumped into from the ascenidng limb?

Answer 19

Blood is supplied by vasa recta without washing gradient away

Question 20

What is the role of the vasa recta in the countercurrent mechanism?

Answer 20

creates a hypertonic soltution around the descendng limb

Question 21

What is the role of the urine in the countercurrent mechanism?

Answer 21

1. urea enters filtrate through glomerular filtration.
2. the urea is trapped in the descending limb until the collecting duct, thus raising its osmolarity. This assist is increasing the amount of NaCl that moves out of the ascending limb into the interstitium.
   3) Urea enters the interstitium in the collecting duct contributing to its hypertonicity meaning more water will be reabsorbed at the descending limb.
   4) Some urea will enter the ascending limb and be recycled to the collecting duct.

Question 22

Describe how renal adjustment deals with acidosis and alkalosis?

Answer 22

acidosis: excrete H+ in urine, reabsorb HCO3-

alkalosis, vice versa

Question 23

What are alpha intercalated cells involved in?
What enzyme is present inside?
What transporters are present and which membrane?

Answer 23

excretion of H+,
carbonic anhydrase,
H+ transported on apical membrane, basolateral membrane cabonate transporter

Question 24

What are alpha intercalated cells involved in?

What enzyme is present inside?

Answer 24

absorbtion of H+,
carbonic anhydrase,
H+ transported on basolateralmembrane, apical membrane cabonate transporter