Integration of Salt and Water Balance Flashcards Preview

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Flashcards in Integration of Salt and Water Balance Deck (14):
1

What happens with dehydration

To get EC osmolarity back to normal

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2

What physiological factors regulates ADH release?

  1. Osmolarity changes <1%. (osmoreceptors) *lower threshold and higher sensitivity
  2. Changes in blood volume >10% (cardiopulonary receptors sense stretching of atria/ventricles → hypothalamus)

3

What senses changes in osmolarity?

Osmoreceptors in hypothalamus sense and stimulate ADH release. 

4

What non-physiological features stimulate ADH secretion

  • Pain, stress
  • Drugs
  • Carcinomas
  • Pulmonary disorders
  • CNS disorders
  • Acohol INHIBITS

5

How is ADH made and released?

ADH is synthesized in the hypothalamus → Travels down axons to the posterior pit. (stored in granules in the nerve terminals) → Released into blood → acts on kidney

6

How exactly does ADH have an affect on the kidneys?

ADH binds to V2 receptors of the Renal ISF side of the tubular cells. This stimulates the insertion of Aquaporin-2 channels on the tubular lumen side.

These are effectively water channels, allowing water reabsorption.

 

The more ADH, the less urine you make!

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7

Central and nephrogenic diabetes insipidus

Inability to respond or produce ADH no matter the osmolarity! Extremely large urine output. 

Central: head injury, infection, tumor
             Damage with hypothalamus or post. pit. 
              No ADH produced
             

Nephrogenic: issue with V2 receptors in the kidney or drugs
                       collecting tubule unresponsive to ADH

8

How do you distinguish between Central and Nephrogenic DI?

Via the Water Deprivation Test. 

 

Dehydrate patient, then give them a ADH-replacement. Only those with a central ADH will go up, as there issue is not with the receptors, but that there is no ADH produced!

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9

Syndrome of inappropriate ADH secretion SIADH. 

What is it? How is it caused? Treatment?

  • Plasma ADH levels higher then should be for the individuals EC osmolarity and volume, so patient inappropriately retains water
  • Posm. significately lower then normal. 
  • If patients water intake is not controlled → hypo-osmolal state with possible dire consequences

Caused by: brain injury/tumor, some anti-cancer drugs

Treatment: Restrict water intake

10

Under what conditions is Renin release increased?

  • Increased Sympathetic Stimulation
  • Decreased afferent arteriole BP
  • Decreased macular densa NaCl delivery.

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11

Once released, draw what Renin does via a flow diagram

Can be blocked via ACE inhibitors or angiotension receptor blockers

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12

What does Angiotensin II do?

  1. increased aldosterone production
  2. Constriction of efferent arteriole
  3. Bind to AT1 receptor, allowing Na+ reabsorption

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13

If the right renal artery becomes abnormally constricted, what will happen to renin secretion by the right and left kidney?

Right kidney: gets lower renal PP via the intrarenal baroreceptor and → increased renin output → elevated angiotensin II and arterial BP 

These both inhibit renin secretion from the left kidney. Acutely you will have overall higher renin levels for the first month

 

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