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HUBS192 > RENAL PHYSIOLOGY III > Flashcards

RENAL PHYSIOLOGY III Flashcards

1
Q

TRUE/FALSE: gain or loss of isosmotic fluid affects both the ICF and ECF

A

false

only affects ECF

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2
Q

what are the 3 important places where water is reabsorbed and what are the portion of the filtered load that those places reabsorbed?

A
  • PCT: 67%
  • DCT: 25%
  • Collecting duct: 2-8%

—> <1-6% of filtered load is excreted

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3
Q

what are the 2 types of water reabsorption in the nephron?

A
  • bulk (obligatory) water reabsorption
  • regulated (facultative) water reabsorption
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4
Q

describe bulk water reabsorption?

A
  • happens at PCT and descending limb of nephron loop
  • accounts for 92% total water reabsorption
  • automatic by leaky epithelia
  • trans and paracellular water reabsorption
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5
Q

describe regulated water reabsorption?

A
  • occurs at the collecting duct
  • accounts for 2-8% of total water reabsorption
  • regulated by anti-diuretic hormone (ADH)
  • tight epithelia
  • only transcellular reabsorption
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6
Q

what are the 4 important places where sodium is reabsorbed and what are the portion of the filtered load that those places reabsorbed?

A
  • PCT: 67%
  • ascending limb: 25%
  • DCT: 5%
  • collecting duct: 2-3%
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7
Q

describe the bulk Na+ reabsorption?

A
  • occurs at the PCT and the ascending limb
  • accounts for 92% of total Na+ reabsorption
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8
Q

describe the regulated Na+ reabsorption?

A
  • accounts for 7-8% of total sodium reabsorption
  • regulated by aldosterone (RAAS)
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9
Q

describe the reabsorption process at the PCT?

A

water
- reabsorption is driven by Na+ reabsorption
- water follows by the paracellular and transcellular pathways because leaky epithelia of PCT

Na+
- transporters such as sodium-glucose cotransport: use Na to reabsorb other solutes such as glucose

chloride (Cl-): follows via paracellular pathway because leaky epithelia of PCT

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10
Q

which part of the nephron loop is permeable to water?

A

descending

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11
Q

which part of the nephron loop is permeable to sodium?

A

ascending

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12
Q

describe the reabsorption process at the nephron loop

A

descending limb: leaky epithelium
- water reabsorbed into peritubular tube via aquaporins or across juntions between cells

ascending limb: reabsorption of Na+ into peritubular fluid

justamedullary nephrons: with the different permeabilities of the loop —> allows a hyper-osmotic medullary gradient (HOMG) to be generated

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13
Q

TRUE/FALSE: water reabsorption in the kidney is independent of sodium reabsorption

A

false
- where sodium moves, water wants to follow
BUT
water reabsorption in the kidney is facilitated by glucose reabsorption

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14
Q

what happens to osmolarity if TBW changes?

A

the plasma ECF osmolarity would be changed

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15
Q

in the ______1______ of ADH, there are no _______2______ in the apical membrane of epithelial cells in the _______3_______. This means that no water can be reabsorbed. Because of this, a _______4_______ volume of ______5______ urine is produced

in the _____6_____ of ADH, there are many _______2______ in the in the apical membrane of epithelial cells in the _______3_______. This means that lots of water can be reabsorbed. Because of this, a _____7______ of _______8______ urine is produced.

A

1: absence
2: aquaporins
3: collecting duct
4: large
5: diluted
6: presence
7: small
8: concentrated

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16
Q

how does ADH delivery work?

A

decrease in TBW –> increase in ECF osmolarity –> detected by osmoreceptors in hypothalamus –> increase in release of ADH in posterior pituitary –> insertion of aquaporins in apical membrane of CD cells –> increase water permeability –> increase in water reabsorption and decrease in urine volume –> ECF osmolarity returns to normal

17
Q

where is ADH secreted?

A

posterior pituitary

18
Q

what happens if our body is intoxicated/dehydrated?

A

intoxicated: hyposmotic in body fluid –> reduce ADH release to increase water excretion

dehydrated: opposite to above

19
Q

what hormone related to sodium is secreted if ECF volume increase/decrease?

A
  • increase: ANP
  • decrease: aldosterone
20
Q

how does RAAS work?

A
  • decrease in blood volume/loss of isosmotic fluid (water + Na+)
  • detected by pressure receptors in the kidney
  • activation of RAAS from adrenal gland
  • increased sodium channels in apical membrane of DCT or CD
  • increase both sodium and water reabsorption
  • return blood volume to normal
21
Q

where is RAAS secreted from?

A

adrenal gland

22
Q

what can you find in normal and pathological urine?

A

normal
- creatinine
- urea
- uric acid
- H+
- Na+
- medications and toxins

pathological
- glucose
- blood: haemoglobin, white blood cells, erythrocytes, RBCs
- protein especially albumin
- bacteria: infection

23
Q

what does protein/glucose/blood presence in urine indicate?

A
  • protein: damage to filtration barrier - glomerulonephitis
  • glucose: uncontrolled diabetes
  • blood: urinary infections

HUBS192 (23 decks)

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