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Anatomy and Physiology II > Lecture 25 > Flashcards

Lecture 25 Flashcards

1
Q

Reabsorption of Bicarbonate, Na+ & H+ Ions: What reabsorbs Na+ and secretes H+?

A
  1. Na+ antiporters
    - PCT cells produce the H+ & release bicarbonate ion to the peritubular capillaries
    - important buffering system
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2
Q

***For every H+ secreted into the tubular fluid,

A

one filtered bicarbonate eventually returns to the blood

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3
Q

secretion =

A

blood to tubule

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4
Q

reabsorption =

A

tubule to blood

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5
Q

Passive Reabsorption in the 2nd Half of PCT: Electrochemical gradients produced by

A

symporters & antiporters causes passive reabsorption of other solutes

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6
Q

What passively diffuses into peritubular capillaries?

A

Cl-, K+, Ca+2, Mg+2 and urea

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7
Q

What promotes osmosis in PCT?

A

Passive Reabsorption in the 2nd Half of PCT-

VERY permeable because of aquaporin-1 channels

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8
Q

Ammonia (NH3) is a

A
  • poisonous waste product of protein deamination in the liver
  • most is converted to urea which is less toxic
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9
Q

Both ammonia & urea are

A

filtered at the glomerus & secreted in the PCT

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10
Q

PCT cells do what?

A

deaminate glutamine in a process that generates both NH3 and new bicarbonate ion.

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11
Q

Bicarbonate diffuses into what?

A

-the bloodstream

-

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12
Q

during acidosis more what is generated?

A

bicarbonate

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13
Q

Reabsorption in the Loop of Henle:

A
  • Tubular fluid

- Sets the stage for independent regulation of both volume & osmolarity of body fluids

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14
Q

Tubular fluid has PCT that does what?

A

-reabsorb 65% of the filtered water so chemical composition of tubular fluid in the loop of Henle is quite different from plasma

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15
Q

Osmolarity of tubular fluid is close to that of blood because why?

A

Since many nutrients were reabsorbed as well

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16
Q

Symporters in the Loop of Henle: Thick limb of loop of Henle has

A

Na+ K- Cl- symporters that reabsorb these ions

17
Q

Symporters in the Loop of Henle: K+ leaks through

A

K+ channels back into the tubular fluid leaving the interstitial fluid and blood with a negative charge

18
Q

Symporters in the Loop of Henle: Cations do what?

A

passively move to the vasa recta

19
Q

Reabsorption in the DCT: 1. Removal of Na+ and Cl- continues in

A

the DCT by means of Na+ Cl- symporters

20
Q

Reabsorption in the DCT: 2. Na+ and Cl- then reabsorbed into

A

peritubular capillaries

21
Q

***DCT is major site

A

where parathyroid hormone stimulates reabsorption of Ca+2

22
Q

***DCT is not very permeable to

A

water so it is not reabsorbed with little accompanying water

23
Q

Reabsorption & Secretion in the Collecting Duct: By end of DCT,

A

95% of solutes & water have been reabsorbed and returned to the bloodstream

24
Q

***Reabsorption & Secretion in the Collecting Duct: 2 Cell types in the collecting duct make the final adjustments

A
  1. Principal cells

2. Intercalated cells

25
Q

***Principal cells do what?

A

reabsorb Na+ and secrete K+

26
Q

***Intercalated cells do what?

A

reabsorb K+ & bicarbonate ions and secrete H+ (buffering, ex. pH)

27
Q

Actions of the Principal Cells: 1st step

A

Na+ enters principal cellsthrough leakage channels

28
Q

Actions of the Principal Cells: 2nd step

A

Na+ pumps keep theconcentration of Na+ inthe cytosol low

29
Q

Actions of the Principal Cells: 3rd step

A

Cells secrete variableamounts of K+, to adjustfor dietary changes in K+intake
-down concentration gradient due to Na+/K+ pump

30
Q

Actions of the Principal Cells: 4th step

A

Aldosterone (hormone) increases Na+ and water reabsorption & K+ secretion by principal cells by stimulating the synthesis of new pumps and channels

31
Q

Secretion of H+ and Absorption of Bicarbonate by Intercalated Cells: 1st Step =

A

Proton pumps secrete H+ into tubular fluid

-can secrete against a concentration gradient so urine can be 1000 times more acidic than blood

32
Q

Secretion of H+ and Absorption of Bicarbonate by Intercalated Cells: 2nd Step =

A

Cl-/HCO3- antiporters move bicarbonate ions into the blood

-intercalated cells help regulate pH of body fluids

33
Q

Secretion of H+ and Absorption of Bicarbonate by Intercalated Cells: 3rd Step =

A

Urine is buffered by HPO4 2- and ammonia, both of which combine irreversibly with H+ and are excreted
-get rid of waste w/o destroying body

Anatomy and Physiology II (26 decks)

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