L18 Gene Models and Nephron Function 2 Flashcards
What is the main function of the loop of Henle?
- Reabsorption of Na+, Cl-, H2O , Ca2+ and Mg2+
- Produce concentrated urine
What are the 3 structural areas of the loop of Henle?
The descending limb, thick ascending limb and thin ascending limb
How is there a potassium gradient established within the TAL?
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
What is the name of the transporter that actively pumps potassium ions into the cell in the TAL?
NKCC2
What is the function of the CLCK and Barttin transporters in the TAL?
The primary function of this channel is to facilitate chloride ion reabsorption from the cell into the bloodstream
How is potassium ions recycled within the TAL?
Diffuses in via NKCC2 and diffuses out via ROMK and potassium channels
ROMK on the apical
K+ on basolateral
Is the transport of Calcium and magnesium ions paracellular or transcellular in TAL?
Paracellular
What is bartter’s syndrome?
Bartter syndrome is a rare genetic disorder that affects the kidneys’ ability to reabsorb salt
What are the symptoms of Bartter’s syndrome? (6)
Salt wasting & polyuria
Hypotension
Hypokalaemia
Metabolic alkalosis
Hypercalciuria - nephrocalcinosis
What is salt wasting and polyuria?
Salt wasting - Excessive loss of sodium through urination..
Polyuria - Excessive urination which leads to dehydration.
What is hypotension ?
Low blood pressure caused by dehydration.
What is Hypokalaemia?
Low level of potassium
What is hypercalciuria?
Excessive loss of calcium through urination which can cause kidney stones.
What happens to the 3 receptors in the TAL within Bartter’s syndrome patients?
- 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
What is metabolic alkalosis?
It’s a condition where the body’s pH level becomes too high, making the blood too alkaline
What is loop diuretics?
They are medications that increase urine production by inhibiting the reabsorption of sodium and chloride in the kidneys
Can you give me two examples of loop diuretics?
Furosemide and Bumetanide
They inhibit reabsorption of NA+ and Cl- in kidneys
What are the effects of Loop diuretics?
- Increase urine production by inhibiting Na+ and Cl- reabsorption, leading to increased fluid excretion
- Reduction in fluid volume can reduce pressure on blood vessels
- leading to lower blood pressure
What happens at the early DT (distal tubule)?
Reabsorption Na+, Cl-, Mg2+
Sensitive to thiazide diuretics
Inhibits reabsorption of ions in the DT
How does the chlorine enter and leave the early distal tubule via transporters?
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
What are thiazide diuretics?
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
What happens to the NCC when thiazide diuretics are administered?
They inhibit the reabsorption of sodium and chloride ions from tubular fluid into the bloodstream which leads to increased excretion
What happens if you’re given too much Thiazide diuretics?
Severe dehydration
Hypokalemia - low K+
Hyponatremia - low Na+
What is Gitelman’s syndrome?
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
Is Gitelman’s syndrome recessive or dominant?
Recessive
What are the symptoms of Gitelman’s syndrome?
Hypotension
Hypokalaemia
Metabolic alkalosis
Hypocalciuria
What difference(s) are there in symptoms between the Bartter’s syndrome and Gitelman’s syndrome?
Bartter’s syndrome - Hypercalciuria (increased calcium excretion)
Gitelman’s syndrome - Hypocalciuria
Gitelman promotes reabsorption of calcium ions so less excreted
What is immunohistochemical analysis?
It is a laboratory technique used to visualize and localize specific proteins or other antigens in cells and tissues.
