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002 - Physio - Renal > (12) - Tubular Reabsorption > Flashcards

(12) - Tubular Reabsorption Flashcards

1
Q

(Importance)

  1. What is the single most critical function of the kidney?
  2. The success of all body systems depends on successful perfusion of all tissues with blood
A
  1. sodium reabsorption and maintntance of an “effective circulating volume”
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2
Q

(Key Points)

  1. The kidneys have separate mechanisms for regulating sodium and water
  2. Total body sodium content is regulated by what?
  3. The majority of Na is reabsorbed where?
A
  1. the kidneys
  2. proximal tubules ( with progressively smaller amounts in the loop of Henle, the distal tubules, and the collecting ducts)
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3
Q

(Key Pints)

  1. Resportbipn of Na is primarily what kind of process?
  2. Reabsorption of Cl- is active or passive?
  3. Reabsorption of water is by what and dependent on what?
A
  1. active, transcellular process (driven by Na-K-ATPase at the basolateral membrance)
  2. both - passive (paracellular) and active (transcellular) (but directly or indirectly coupled to reabsorption of Na)
  3. osmosis and dependent of reabsorption of solute
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4
Q

(Key Points)

  1. Reabsorption of most of the filtered water, anions, and osmotic concent is linked to what?
A
  1. active reabsorption of Na

(just read the thing)

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5
Q
A
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6
Q

(Goes with prior cards)

A

I guess we’ll get to this later

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7
Q
A
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8
Q

(Renal Sodium Handling)

(REabsorption of sodium is the most important function of the kidneys)

  1. most renal energy used to perform this task
  2. maintenance of sodium balance paramount
  3. ECF volume is sodium-dependent
A
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9
Q
A

B

because it will follow sodium - and sodium doesn’t cross ICF

he talked about this for awhile… at 1:08 or so

the answer might actually be D… eck

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10
Q

(ECF volume is sodium dependent)

  1. sodium restricted to certain fluid spaces (ECF)
  2. water follows sodium

(Body tonicity is tightly regulated to “set point”)

  1. do what to achieve this goal?
  2. what percent saline is isotonic?
  3. Sodium content determines the volume of the ECF (which determines tissue perfusion)
  4. Does sodium concent determine the plasma sodium concentration?
A
  1. add or subtract water
  2. 0.9%
  3. no
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11
Q
A

only one - one liter

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12
Q

(Sodium Reabsorption)

  1. vast majority of filtered Na is reabsorbed (most happens in proximal tubule)
  2. PCT?
  3. TAL?
  4. Early DCT?
  5. Late DCT and CD?
A
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13
Q

(Proximal Tubular Na Rebsorption)

(Differences between early and late PT)

  1. early?
  2. late?
  3. answer quesation
A
  1. reabsorbed with HCO3 and organic solutes
  2. reabsorbed with Cl; no organic solutes

(IMPORTANT CONCEPT - reabsorb most important stuff first)

  1. C (cause 67% of Na is reabsorbed and they are proportional)
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14
Q
A
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15
Q

PHARM

if you put something in the lumen - and it stays in the lumen - it will carry water with it for entire length of nephron (mannitol does this)

furosemide - loop diuretc - acts on loop of Henle

so ones that act early (carbonic anhyrase inhibitors) do leave Na in th elumen - but there are many opportunities to reabsor it as you go on so these aren’ta s powerful

he isn’t going to ask us what specific diuretic acts on which site

A
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16
Q

(By Midpoint of the PT)

  1. how much of filtered glucose is reabsorbed?
  2. what percent of filtered HCO3 is reabsorbed?
  3. How much of filtered phoshpate, lactate, and citrate hae been reabsorbed?
  4. what portion of Na reabsorbed?
A
  1. 100%
  2. 85%
  3. most
  4. large portion
17
Q
A
18
Q

(Late Proximal Tubule)

(Fluid entering late PT very different from glomerular filtrate)

  1. organic solutes present?
  2. high in what?

(Primarily reabsorption of NaCl)

  1. what is the driving force?
  2. has transcelluar and paracellular components
A
  1. mostly gone
  2. chlordide (Early PT, HCO3 reabsorbed preferentially over Cl – substantial removal of water in early PT)
  3. high chloride
19
Q
A
20
Q

(Glomerulotubular balance)

  1. Which is more important - control of GFR or regulation of tubular Na reabsorption?
  2. changes in GFR –> ?
  3. the percentage of filtered Na remains approximately constant
A
  1. regulation of tubular Na reabsorption
  2. proportional changes in reabsorption of Na by the proximal tubules
21
Q

(Glomerulotubular Balance)

(Changes in PT reabsorption are appropriate!)

  1. does glomerulotubular balance mean that percentage reabsorbed does not change?
  2. When changes in percentage reabsorbed occur, they are caused by what?
  3. what is the goal?
  4. Mechanisms altering glomerultubular balance are entirely what?
A
  1. NO
  2. factors other than changes in GFR
  3. prevent large changes in Na excretion
  4. intrarenal
22
Q
A

C

23
Q

(Glomerular Balance: Mechanisms)

  1. GT balance secondary “line of defense” to prevent what?

2-3. Mechanism of GT balance depends on relationship between what two things?

A
  1. excessive urinary Na loss (autoregulation is first)
  2. filtration fraction
  3. Peritubular starling forces
24
Q

(The loop of Henle)

(Thin descending limb)

  1. permeable to what?

(Thin ascebding limb)

  1. permeable to NaCl?
  2. permeable to water?

(Thick ascending limb)

  1. active reabsorption of what?
  2. load-dependent
  3. permeable to water?
A
  1. water and small solutes
  2. yes
  3. no
  4. Na
  5. nope

(collecting tubules are variably permeable to water due to insertion of aquaporin)

25
Q

(Sodium and loop of Henle)

  1. passive exit from what?

(Active reabsorption of Na from thick ascending loop (TAL))

  1. load dependent?
  2. increased Na load enters TAL –> ?
A
  1. thin loops
  2. yep
  3. increased TAL reabsorption of Na+
26
Q

(Distal Tubule and Collecting Duct)

  1. is sodium reabsorption load dependent?

(mechanisms of Na transport differ by location)

  1. early distal tubules
  2. late distal tubules and collecting ducts
A
  1. yes
27
Q

(Cortical Diluting Segment)

(fluid entering the segment is already dilute)

  1. Passage through the cortical diluting segment does what to the tubular fluid?

(early distal tubule epithelium is impermeable to water)

  1. reabsorbs what?
  2. any water reabsorption?
A
  1. further dilutes
  2. water
  3. no
28
Q

(Late Distal Tubule and Collecting Duct)

  1. what percentage of Na reabsorbed?
  2. fine adjustments to Na conc occur here

3-4. What are the two major cell types (plus their functions)?

A
  1. only 3%
29
Q
A
30
Q
A

1

002 - Physio - Renal (19 decks)

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