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Physiology - Guyton & Hall > Chapter 31 - Acid Base Regulation > Flashcards

Chapter 31 - Acid Base Regulation Flashcards

1
Q

H+ secretion and HCO3 reabsorption occur in virtually all parts of the tubules except in ()

A
  • descending thin limb of the LOH
  • ascending thin limb of the LOH
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2
Q

For each HCO3 reabsorbed, what is secreted?

A

Hydrogen ion

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3
Q

Which segments secrete hydrogen ions into the tubular fluid (renal lumen) by sodium-hydrogen counter-transport (exchanger protein)

A
  • proximal tubule
  • thick segment of the ascending LOH
  • early distal tubule
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4
Q

The sodium gradient for the sodium-hydrogen exchanger protein in the luminal membrane is established by

A

Na-K ATPase pump in the basolateral membrane

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5
Q

(1)% of the bicarbonate is reabsorbed for every (2)mEq of H+ secreted everyday

A

(1) 95%
(2) 4000 mEq

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6
Q

Normal H+ concentration of body fluids

A

0.00004 mEq/L

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7
Q

Rapidly dissociates and releases especially large amounts of H+ in solution

Ex. HCl

A

Strong Acid

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8
Q

Less likely to dissociate their ions, release H+ with less vigor

Ex. H2CO3

A

Weak Acid

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9
Q

One that reacts rapidly and strongly with H+ hence quickly removes H+ from a solution

Ex. OH- (which reacts with H+ to form H2O)

A

Strong Base

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10
Q

Binds with H+ more weakly

Ex. HCO3-

A

Weak Base

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11
Q

Most important weak acid in the body

A

H2CO3 - Carbonic acid

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12
Q

Most important weak base in the body

A

HCO3- - Bicarbonate ions

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13
Q

Normal pH of the body is

A

pH 7.4
pH 7.35 - 7.45

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14
Q

pH and H+ concentration of Body Fluids

A

Most acidic is Gastric acid (HCl)

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15
Q

Normal Arterial Blood pH: (1)
pH for acidosis: (2)
pH for alkalosis: (3)

A

(1) pH = 7.4
(2) pH < 7.4
(3) pH > 7.4

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16
Q

3 primary systems that regulate the H+ conc. In the body fluids to prevent acidosis/alkalosis

A

(1) chemical acid-base buffer systems of body fluids: combine to acids or bases to neutralize

(2) respiratory center: regulate removal of CO2 and carbonic acid from ECF

(3) kidneys: excrete excess acid or base

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17
Q

(True/False)

Buffers stabilize pH by eliminating H+ or adding them to the body

A

False

Buffers DO NOT eliminate H+ from or add them to the body. They only keep them tied up

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18
Q

Any substance that can reversibly bind H

A

Buffer

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19
Q

Explain the Bicarbonate Buffer System

A
20
Q

Solubility coefficient of CO2 at body temperature

A

0.03 mmol/mmHg

21
Q

(1) Acid-base balance shift in Increase in HCO3-

(2) Regulated by

A

(1) Alkalosis

(2) kidneys

22
Q

(1) Acid-base balance shift in increase in PCO2

(2) Regulated by

A

(1) Acidosis

(2) rate of respiration

23
Q

4 Major Acid-Base Disorders

A
  1. Respiratory acidosis
  2. Respiratory alkalosis
  3. Metabolic acidosis
  4. Metabolic alkalosis
24
Q

Acidosis caused by a primary decrease in HCO3- conc

A

Metabolic acidosis

25
Q

Alkalosis caused by a primary increase in HCO3- concentration

A

Metabolic alkalosis

26
Q

Acidosis caused by an increase in PCO2

A

Respiratory acidosis

27
Q

Alkalosis caused by a decrease in PCO2

A

Respiratory alkalosis

28
Q

Explain the Phosphate Buffer System

A
29
Q

Plays a minor role as an extracellular buffer but is important in buffering the tubular fluids of the kidneys and intracellular fluid

pK (6.8)

A

Phosphate buffer system

30
Q

Buffer in RBC

A

Hemoglobin (HB)

31
Q

About (1) mol/L of dissolved CO2 is normally in the extracellular fluid, corresponding to a PCO2 of (2)mmHg

A

(1) 1.2 mol.L
(2) 40 mmHg

CO2 is formed continually in the body by intracellular metabolic processes

32
Q

Effect of the rate of alveolar ventilation to PCO2 in extracelular fluid

A

Increasing alveolar ventilation decreases extracellular fluid H+ concentration and raises pH

High alveolar ventilation, blows off increased amounts of CO2, which lowers PCO2 (ALKALINE)

Vice versa is true - increased H+ conc. will stimulate alveolar ventilation

33
Q

H+ concentration CONTROL by the respiratory system is what type of feedback mechanism

A

Negative Feedback Mechanism

34
Q

Daily, the body produces ()mEq of nonvolatile acids mainly from metabolism of proteins

Nonvolatile are not H2CO3 which cannot be excreted by the lungs

A

80 mEq

35
Q

Function of the kidney to maintain acid-base balance

A

(1) kidney must reabsorb virtually all filtered HCO3
(2) Must secrete into the urine the daly production of nonvolatile acids

Renal excretion is the primary mechanism for removal of nonvolatile acids, but a task more important is the prevention of loss of bicarbonate in the urine

36
Q

Kidneys regulate extracellular fluid H+ concentration through:

A

1) secretion of H+
2) reabsorption of filtered HCO3-
3) procuction of new HCO3-

37
Q

Bicarbonate transport across the basolateral membrane is facilitated by

A
  • early PCT: sodium-bicarbonate co transport
  • late PCT, thick ascending LOH, collecting tubules & ducts: chloride-bicarbonate exchange protein
38
Q

(True/False)

Bicarbonate and hydrogen ion normally “titrate” each other in the kidney tubules. This is however not exact where excess hydrogen in the tubules are the ones to be excreted in the urine

A

True

excess hydrogen (80 mEq/day) rids the body of nonvolatile acids produced by metabolism - excreted as phosphate and ammonia

39
Q

Hydrogen secretion in the late distal tubules to the collecting ducts is via

A

Primary active transport

40
Q

Primary active secretion of H+ occurs in what cells of the late distal tubule and in the collecting tubules

A

Type A Intercalated cells

41
Q

(1) Most important buffers in urine
(2) other weak buffer system in urine

A

(1) phosphate and ammonia buffer system
(2) urate and citrate

42
Q
A

Phosphate Buffer system carries excess H+ into the urine and generates new bicarbonate

43
Q

Excretion of Excess H+ and generation of new HCO3 by ammonia buffer system

A

Notes:
* ammonium ion is synthesized from glutamine (amino acid metabolite from liver)

  • Glutamine forms 2 ammonia and 2 bicarbonate in the kidney cell
  • ammonia is released in lumen via counter transport with sodium
44
Q

Glutamine is transported in which part of the kidney

A

(1) PCT
(2) thick ascending limb of LOH
(3) DCT

45
Q

REGULATION OF RENAL TUBULAR H+ SECRETION

A

Physiology - Guyton & Hall (21 decks)

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