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Human Physiology > Unit 4 Ch. 20 > Flashcards

Unit 4 Ch. 20 Flashcards

1
Q

What is hypotonic and hypertonic?

A
  • hypertonic: too little water

- hypotonic: too much water

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2
Q

How can kidneys regulate water?

A
  • can excrete
  • can retain (Vasopressin)
  • can’t reclaim water
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3
Q

How does urine concentration differ along the length of the nephron?

A
  • vertical concentration gradient
  • more concentrated in medulla than cortex
  • urine concentration depends on needs
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4
Q

What is the role of the medullary countercurrent system?

A
  • Loop of Henle establishes conc. gradient
  • Countercurrent due to flow in opposite directions
  • Gradient maintained by vasa recta.
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5
Q

What is the difference between the ascending and descending Loop of Henle?

A
  • Descending: Water permeable, not solute

- Ascending: NaCl permeable, ALWAYS H2O impermeable.

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6
Q

What is countercurrent multiplication?

A
  • Fluid leaving loop of Henle has been concentrated 4x and diluted 3x.
  • Dilute urine excreted.
  • 200 mOsM difference between vasa rect and ascending limb.
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7
Q

What is the role of the vasa recta?

A
  • preserves concentration gradient.

- Because it follows the Loop of Henle

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8
Q

What is the role of Vasopressin?
Where does it bind and by what pathway?
What stimulates it?

A
  • Stimulated by hypertonic blood (NEED WATER)
  • binds to membrane receptor
  • cAMP 2nd messenger pathway, releases vesicles containing aquaporins.
  • Distal and collecting tubules are impermeable to H2O except with Vasopressin (ADH). bye bye watery pee
  • Vasopressin leads to less watery pee.
  • If I’m dying in a desert and my life sucks I will have lots of Vasopressin creating aquaporins.
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9
Q

What is the different in H2O reabsorption in the presence and absence of vasopressin?

A
  • Present: Maximal ADH urine up to 1200 mOsM

- absent: minimal ADH urine down to 100 mOsM

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10
Q

How does Na+ load affect reabsorption?

A
  • Proximal tubule and Loop of Henle: Na+ reabsorption constant
  • Distal tubule: Na+ reabsorption subject to hormonal control. Greater load, less reabsorbed.
  • Greater Na+ load, greater ECF volume, greater BP (H2O and Na are biffles)
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11
Q

What is the role of Renin?

A
  • Secreted by kidney in response to dec. NaCl, ECF volume, and consequently BP.
  • Granular cells stimulated by: Macula Densa, Baroreceptors, Sympathetic Innervation
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12
Q

What is the role of the RAAS?

A

-results in Na+ reabsorption and H2O retention. (Passive Cl- too)

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13
Q

Trace the RAAS pathway.

A
  • Renin secreted by detection of decreased BP
  • Renin (kidney) activates angiotensinogen (liver) into Angiotensin I
  • ACE (lung) conveerts Angiotensin I to Angotensin II.
  • Ang II stimulated secretion of aldosterone (adrenal cortex).
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14
Q

What is the role of Aldosterone in the RAAS?

A
  • Increase Na+ reabsorption in distal/collecting duct (hormonal control aspect).
  • More Na+ channels and K+ pumps
  • Net Result: More Na+ into ECF, so more water follows.
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15
Q

What are the roles of angiotensin II?

A
  • vasoconstriction
  • thirst stimulating (to increase BP by volume increase from drinking)
  • stimulated ADH (water retention)
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16
Q

What is the role of atrial natriuretic peptide?

A
  • Opposes RAAS to increase Na+ (and water, they’re BIFFLES) excretion
  • Vasodilation of glomerular afferent arterioles to increase GFR
  • inhibits sympathetic activity
17
Q

How does acid-base balance affect the system?

A
  • Buffers prevent wide swings in pH
  • Lungs reflexively respond to most pH disturbances
  • Kidneys, secondary response, but can compensate for remaining pH disturbances.
18
Q

What is the role of buffers?

What is the difference in effect of increasing H+ v. increasing bicarbonate?

A
  • They are found within the cell and in the plasma
  • Example, bicarbonate (HCO3)
  • Plasma bicarbonate 60,000x more concentrated than H+ in the plasma.
  • Increasing H+ has greater effect on plasma pH than increasing HCO3
19
Q

What is the effect on acidosis of hypoventilation and hyperventilation?

A
  • hyperventilation: counters acidosis

- hypoventilation: exacerbates acidosis

20
Q

What is the proximal tubule role on acid/base balance?

A
  • Kidneys secrete H+ and reabsorb HCO3 in proximal tubules

- Result: Na+ and HCO3- (to act as ECF buffer) reabsorption (inc pH) and secrete H+ (buffered in urine)

21
Q

What is the role of the collecting duct on acid/base balance? Which intercalated cells function acidosis and which function in alkalosis?

A
  • acidosis: Type A intercalated cells. H+ excreted, HCO3- and K+ reabsorbed
  • alkalosis: Type B intercalated cells. H+ reabsorbed, HCO3- and K+ excreted.

Human Physiology (9 decks)

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