Describe the positive feedback mechanism used by the nephron loop to make the me

Question

Describe the positive feedback mechanism used by the nephron loop to make the medulla salty. What is the purpose of this mechanism?
What factors stimulate breathing? Between O2 and CO2, which is more important in terms of stimulation of breathing? Why?
Describe the positive feedback mechanism used by the nephron loop to make the medulla salty. What is the purpose of this mechanism?
What factors stimulate breathing? Between O2 and CO2, which is more important in terms of stimulation of breathing? Why?

What factors stimulate breathing? Between O2 and CO2, which is more important in terms of stimulation of breathing? Why?

Explanation / Answer

1)interstitium is made salty by counter current mechanism i.e, the concentrations of SODIUM and UREA are kept high in the medullary interstitium by the slow blood flow in the vasa recta

Descending vasa recta has facilitated transporter for urea whereas ascending vasa recta helps to conserve solutes.

Sodium and urea are reabsorbed and are accumulated in medulla where they get absorbed by descending vasa recta and returns to the interstitium by ascending vasa recta.

This counter current traps solutes in the medulaary interstitium and increases the osmalality.

Also,water diffuses from the descending vasa recta into the interstitium and thus plasma protein concentration inthe descending limb of vasa recta increases.In ascending vasa recta,increased vasa recta causes capillaries to take in fluids.

Therefore,water reabsorbed by nephron is removed from interstitium and return to the general circulation.Therefore,solutes recirculate in the medulla,medullary hyperosmalality is maintained.

2)Breathing is stimulated by;

High arterial pCO2

Low arterial pO2

Low pH

CO2 is more important in terms of stimulation of breathing as it acts on chemoreceptors present in brain.

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