Acid-Base Regulation - Quiz 4 Flashcards Preview

Summer 2020 - Physiology 2 - Renal > Acid-Base Regulation - Quiz 4 > Flashcards

Flashcards in Acid-Base Regulation - Quiz 4 Deck (39)
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1

What is the Normal amount of H+ in the ECF?

40 nEq/L

2

The Lower & Higher Limit of pH at which a person can live for a few hours is ___ & ___ respectively.

The Lower & Higher Limit of pH at which a person can live for a few hours is 6.8 & 8.0 respectively.

3

What is an acid?

Proton Donor

4

What does the Henderson-Hasselbalch equation describe?

Relationship b/t pH, PaCO2, and Serum Bicarb

5

What is the Solubility Coefficient for CO2

0.03 mmol/mmHg

6

What is a base?

Proton Acceptor

7

What is the role of Weak Acids or Bases in regards to pH?

Act as Buffers to minimize pH changes

8

When are pH buffers most efficient?

When pH = pKA

9

What are the pH Body Buffers?

Bicarb - strongest ECF buffer

Hgb

Proteins

Phosphate

Ammonia

10

What are the Primary Systems that regulate H+ and Prevent Acidosis/Alkalosis?

Chemical Acid-Base Buffers of Body Fluid

Respiratory Center

Kidneys - slowest, but strongest regulator

11

True or False: The Bicarb buffer is effective Against both Metabolic & Respiratory acid-base imbalances.

FALSE - Bicarb is effective against Metabolic, but not Respiratory acid-base imbalances

12

What is the pKa of Bicarb?

pKa = 6.1

13

How do the Kidneys increase Bicarb Reabsorption during Acidosis?

  1. CO2 + Water = H2CO3 (Carbonic Acid)
  2. H2CO3  ---> H+  +  HCO3-
  3. H+ secreted into Proximal Tubule & Bicarb is Reabsorbed
  4. H+ in Proximal Tubule combines w/ Filtered Bicarb = H2CO3-
  5. Carbonic Anhydrase replaces CO2 by Splitting Bicarb into CO2 & Water

14

By which mechanism is H+ secreted into the Tubular Fluid?

Sodium-Hydrogen Counter-Transport

15

How much Filtered Bicarb is reabsorbed in the Proximal Tubule?

80-90 %

The rest reabsorbs in the Distal Tubule

16

By which mechanism is H+ secreted in Distal Tubule

H+ Pump

17

How is H+ secreted into the Tubular Fluid in the Collecting Duct?

Kis exchanged for H+

18

How does Phosphate play a role in Acid Excretion?

HPO42- combines w/ the H+ in the Tubule Fluid to form H2PO4- which CANNOT be reabsorbed and gets trapped in urine

19

Why is Phosphate effective as a buffer in acidic urine?

Phosphate has pKA of 6.8

20

How does Ammonium (NH4) work as a Buffer in the Collecting Tubules vs the Proximal, Distal, & TAL?

Collecting Duct - Ammonia (NH3) combines w/ H+ to make NH4, then excreted. Bicarb is made in the process

Proximal, Distal, & TAL - NH4 is made from Glutamine, then excreted. Bicarb is made in the process

21

What is the main mechanism of Acid Elimination w/ Chronic  Acidosis?

NH4 Excretion

22

What are the common situations in which Alkalosis occurs?

Sodium Depletion/Contraction Alkalosis - More sodium goes into Proximal Tubule & Co-Transports Chloride. Bicarb is reabsorbed in exchange w/ Chloride. This happens w/ chronic diuretics.

Increased Aldosterone - Increases Na reabsorption & H+ secretion in the Distal Tubule

23

What is Base Excess?

Amount of Acid/Base needed to return pH back to 7.4

(+) = Metabolic Alkalosis

(-) = Metabolic Acidosis

24

What causes Increased H+ Secretion & Bicarb Reabsorption?

↓ECF

↑Angiotensin II

↑Aldosterone

Hypokalemia

Hypocalcemia

25

How much does the PaCO2 increase w/ a 1 mEq/L increase in Bicarb?

~ 0.5

26

How does Potassium Levels change w/ a 0.1 increase in pH?

~ 0.5 mEq/L

27

How is Metabolic Acidosis treated?

Treat Underlying Cause

Sodium Bicarb (Dont give to pts w/ Resp Failure)

Dialysis

28

How is Alkalosis treated?

IV HCl

Spironolactone

Treat Underlying Problem

29

How is the Cerebral Blood Flow affected by reducing ventilation by half & doubling PaCO2?

Doubles Cerebral Blood Flow

30

How is the Anion Gap calculated?

Na+ - [Cl- + HCO3-]

Normal: 7 - 14 mEq/L