L18 Gene Models and Nephron Function 2

Question 1

What is the main function of the loop of Henle?

Answer 1

• Reabsorption of Na+, Cl-, H2O , Ca2+ and Mg2+
• Produce concentrated urine

Question 2

What are the 3 structural areas of the loop of Henle?

Answer 2

The descending limb, thick ascending limb and thin ascending limb

Question 3

How is there a potassium gradient established within the TAL?

Answer 3

1) NKCC2 simultaneously moves 1 sodium ion, 1 potassium ion and 2 chloride ions from the tubular fluid into the cell
2) Potassium channels allow K+ to exit cell and enter interstitial fluid which maintains a concentration gradient, with a higher conc inside the cell

NKCC2 on apical
Potassium channels on basolateral

Question 4

What is the name of the transporter that actively pumps potassium ions into the cell in the TAL?

Answer 4

NKCC2

Question 5

What is the function of the CLCK and Barttin transporters in the TAL?

Answer 5

The primary function of this channel is to facilitate chloride ion reabsorption from the tubular fluid into the cell

Question 6

How is potassium ions recycled within the TAL?

Answer 6

Diffuses in via NKCC2 and diffuses out via ROMK and potassium channels

ROMK on the apical
K+ on basolateral

Question 7

Is the transport of Calcium and magnesium ions paracellular or transcellular in TAL?

Answer 7

Paracellular

Question 8

What is bartter’s syndrome?

Answer 8

Bartter syndrome is a rare genetic disorder that affects the kidneys’ ability to reabsorb salt

Question 9

What are the symptoms of Bartter’s syndrome? (6)

Answer 9

Salt wasting & polyuria
Hypotension
Hypokalaemia
Metabolic alkalosis
Hypercalciuria - nephrocalcinosis

Question 10

What is salt wasting and polyuria?

Answer 10

Salt wasting - Excessive loss of sodium through urination..
Polyuria - Excessive urination which leads to dehydration.

Question 11

What is hypotension ?

Answer 11

Low blood pressure caused by dehydration.

Question 12

What is Hypokalaemia?

Answer 12

Low level of potassium

Question 13

What is hypercalciuria?

Answer 13

Excessive loss of calcium through urination which can cause kidney stones.

Question 14

What happens to the 3 receptors in the TAL within Bartter’s syndrome patients?

Answer 14

• NKCC2: decreased reabsorption of NA+, 2CL- and K+
• ROMK: Reduces the recycling of potassium back into the tubular fluid
• CLCK and Barttin: Reduced sodium and potassium reabsorption which affects gradient

Question 15

What is metabolic alkalosis?

Answer 15

It’s a condition where the body’s pH level becomes too high, making the blood too alkaline

Question 16

What is loop diuretics?

Answer 16

They are medications that increase urine production by inhibiting the reabsorption of sodium and chloride in the kidneys

Question 17

Can you give me two examples of loop diuretics?

Answer 17

Furosemide and Bumetanide

They inhibit reabsorption of NA+ and Cl- in kidneys

Question 18

What are the effects of Loop diuretics?

Answer 18

• Increase urine production by inhibiting Na+ and Cl- reabsorption, leading to increased fluid excretion
• Reduction in fluid volume can lower blood pressure
• Reduces pressure on blood vessels, leading to lower blood pressure

Question 19

What happens at the early DT (distal tubule)?

Answer 19

Reabsorption Na+, Cl-, Mg2+
Sensitive to thiazide diuretics

Inhibits reabsorption of ions in the DT

Question 20

How does the chlorine enter and leave the early distal tubule via transporters?

Answer 20

1) NCC - (Sodium-Chloride Cotransporter) transports sodium and chloride ions from the tubular fluid into the cell
2) CLCK and Barttin transports Cl- out of cell into interstitial fluid

Question 21

What are thiazide diuretics?

Answer 21

They are a class of medications that work by inhibiting the reabsorption of sodium and chloride ions in the distal convoluted tuble of the kidney

Question 22

What happens to the NCC when thiazide diuretics are administered?

Answer 22

They inhibit the reabsorption of sodium and chloride ions from tubular fluid into the bloodstream which leads to increased excretion

Question 23

What happens if you’re given too much Thiazide diuretics?

Answer 23

Severe dehydration
Hypokalemia - low K+
Hyponatremia - low Na+

Question 24

What is Gitelman’s syndrome?

Answer 24

Gitelman syndrome affects the way the kidneys reabsorb salt and other minerals. Often characterised by a defect in the NCC in the DT of kidney

Question 25

Is Gitelman’s syndrome recessive or dominant?

Answer 25

Recessive

Question 26

What are the symptoms of Gitelman’s syndrome?

Answer 26

Hypotension
Hypokalaemia
Metabolic alkalosis
Hypocalciuria

Question 27

What difference(s) are there in symptoms between the Bartter’s syndrome and Gitelman’s syndrome?

Answer 27

Bartter’s syndrome - Hypercalciuria (increased calcium excretion)
Gitelman’s syndrome - Hypocalciuria

Gitelman promotes reabsorption of calcium ions so less excreted

Question 28

What is immunohistochemical analysis?

Answer 28

It is a laboratory technique used to visualize and localize specific proteins or other antigens in cells and tissues.