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Physiology 2 > L6: ECF 1 > Flashcards

L6: ECF 1 Flashcards

1
Q

Na+ regulation responds primarily to changes in ***.

A

Blood volume, driven mainly by changes in blood pressure

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2
Q

What is the primary effector for Na+ regulation?

A

Renin-angiotensin-aldosterone system (RAAS)

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3
Q

When is RAAS activity increased?

A

When blood pressure decreases

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4
Q

Water regulation is responsive to changes in ** and **.

A

Osmolarity and volume of ECF

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5
Q

What does aldosterone do?

A

Stimulates Na+ reabsorption in the late distal tubule and collecting duct. Also stimulates K+ secretion.
-Na retention entails loss of K

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6
Q

What two things stimulate aldosterone release?

A

Increases in angiotensin II or plasma K+

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7
Q

What kind of receptor does aldosterone bind to?

A

Mineralcorticoid receptors in principal cells

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8
Q

What does the Aldo-MR complex stimulate?

A

Transcription resulting in up-regulation of epically ENaCs, apical K+ channels, Na+/K+ ATPase, mitochondrial metabolism, and H+ ATPase

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9
Q

What is aldosterone antagonized by?

A

Spironolactone

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10
Q

What is the primary control of aldosterone secretion?

A

Plasma AT II concentration

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11
Q

What does ATII do? (5)

A

1) Powerful vasoconstrictor
2) stimulates release of aldosterone
3) stimulates Na+/H+ exchange in the proximal nephron
4) stimulates thirst
5) increases salt retention and elevates arterial blood pressure

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12
Q

How do low levels of AT II affect GFR?

A

Low levels causes primarily vasoconstriction of the efferent arterioles. GFR is maintained or maybe increased

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13
Q

How do high levels of AT II affect GFR?

A

high levels have increased effects on afferent arterioles, which reduces glomerular filtration coefficient (Kf) at mesangial cells, and greatly reduces RBF. GFR decreases

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14
Q

What does AT II stimulate production of?

A

PGE2 and PGI2

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15
Q

What controls Angiotensin II levels?

A

Renin

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16
Q

What are the 3 components of renin release by the JGA?

A

1) intrarenal baroreceptors
2) macula dense
3) renal sympathetic nerves

17
Q

How do intrarenal baroreceptors affect renin release?

A

Granular cells of the JGA respond to pressure in afferent arterioles. Renin release is inversely released to pressure in afferent arterioles.

18
Q

How does the macula densa affect renin release?

A

Macula densa senses flow to distal tubule, renin is inversely related to GFR

19
Q

How do renal sympathetic nerves affect renin release?

A

Stimulation of renal sympathetic nerves increase renin release via stimulation of B receptors

20
Q

What converts angiotesinogen to angiotensin I?

A

Renin

21
Q

What converts AT I to ATII?

A

Angiotensin Converting Enzyme (ACE)

22
Q

What releases ANP and when?

A

The atria when pressures are high

23
Q

What does ANP do?

A
  • Increases GFR and the filtered load of NaCl (afferent arteriole becomes dilated and efferent becomes constricted)
  • Decreases NaCl reabsorption by the collecting duct (directly inhibits secretion of renin and aldosterone, directly inhibits Na+ uptake by the medullary CD)
24
Q

What is the most important hormone in regulating water balance?

A

ADH

25
Q

Where is ADH released from and when?

A

From the pituitary when plasma osmolarity increases or plasma volume decreases

26
Q

Does ADH affect NaCl excretion?

A

Not really

27
Q

How does ADH restore hypovolemia?

A
  • Increases CD permeability to water (water will leave CD to be reabsorbed)
  • increases NKCC2 transporters in the LOH (increased gradient)
  • increases permeability of inner medullary CD to urea
28
Q

Where does aldosterone come from?

A

The adrenal cortex

29
Q

What is normal body osmolarity?

A

290 mOsm/L

30
Q

How does the body try to correct for a drop in plasma volume?

A

By increasing ADH to restore hypovolemia

31
Q

What is osmolar clearance?

A

Th ml/min of blood plasma that is cleared of osmotically active particles
** calculated with clearance equation Cosm= Uosm(V)/Posm

32
Q

What is normal Cosm?

A

1-2 mL/min

33
Q

What does a reduced Cosm mean?

A
  • there is a positive osmolar balance because it is not being cleared out (progression towards edema)
  • May be caused by decreased GFR and increased aldosterone
34
Q

What does an increased Cosm mean?

A
  • There is “dumping” of osmolytes leading to a loss of ECF
  • Diuretics, reduced aldosterone or any disease that reduces the ability of the kidney to reabsorb normally may cause this

Physiology 2 (13 decks)

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