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Flashcards in Acid/Base Phys Deck (54)
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1

LO 1. Define the Henderson-Hasselbalch Equation for Bicarbonate/CO2.

H2O + CO2 H2CO3 H+ + HCO3- pH = 6.1 + log [HCO3] / 0.03xPCO2 For a normal bicarbonate concentration of 24 mM (at sea-level) and an arterial PCO2 of 40 Torr, the Henderson-Hasselbalch equation gives arterial blood pH of 7.40.

2

What is normal human pH?

normal pH is 7.4 (7.38-7.43, perhaps a bit higher here in Denver)

3

What are the 2 major types of buffers?

intracellular and extracellular

4

What are the intracellular buffers?

organic phosphates, proteins, ESPECIALLY hemoglobin

5

What are the extracellular buffers?

phosphate, ESPECIALLY bicarbonate and plasma proteins (mostly albumin)

6

pH = pK + log [A-] [HA]

Henderson-Hasselbalch Equation

7

For humans, the best buffer ought to be close to what pH?

7.4

8

______ is the conjugate base of carbonic acid.

Bicarbonate

9

Bicarbonate is the conjugate base of _______.

carbonic acid

10

Why is bicarbonate the most important buffer in the body?

  1. It is present in relatively high concentration (higher than phosphate)
  2. The pK is relatively close to arterial pH
  3. The conjugate acid, CO2, is readily controlled via ventilation by the lungs

11

_______ has a pK of 7.9.

Deoxyhemoglobin

12

Deoxyhemoglobin has a pK of _____.

7.9

13

Carbon dioxide can then diffuse into red blood cells, where it is rapidly converted to bicarbonate and the protons are buffered by _______.

deoxyhemoglobin

14

Carbon dioxide can then diffuse into red blood cells, where it is rapidly converted to ______ and the protons are buffered by deoxyhemoglobin.

bicarbonate

15

The acid/base status of normal arterial blood can be altered in two general ways: (a) ________, or (b) by too much or too little acid, resulting in a metabolic disturbance.

by altering PCO2 resulting in a respiratory disorder

16

The acid/base status of normal arterial blood can be altered in two general ways: (a) by altering PCO2 resulting in a respiratory disorder or (b) ______.

by too much or too little acid, resulting in a metabolic disturbance

17

Too much acid in the blood is referred to as ______, and too much base in the blood is referred to as ______.

academia; alkalemia

18

Because CO2 can be regulated by the _______ and bicarbonate can be regulated by the _______, the body will attempt to compensate for any acid-base disturbance to try and correct the pH back towards normal.

lungs; kidneys

19

What is respiratory acidosis?

an increase in arterial PCO2, leading to a decrease in pH

20

This is an increase in arterial PCO2, leading to a decrease in pH.

respiratory acidosis

21

What can lead to chronic respiratory failure?

  1. emphysema
  2. chronic bronchitis (COPD)
  3. bronchiectasis
  4. Central hypoventilation disorders (obesity hypoventilation)
  5. neuromuscular diseases (e.g. ALS, AKA Lou Gehrig’s disease)

22

What causes acute respiratory failure?

1. drugs (opiates, benzos, EtOH) 2. muscle fatigue

23

Which compensatory mechanism is slow, taking 2-3 days to complete?

bicarbonate conservation in the kidneys

24

What is respiratory alkalosis?

a decrease in arterial PCO2, leading to an increase in pH

25

This is a decrease in arterial PCO2, leading to an increase in pH.

respiratory alkalosis

26

What are the most common causes of chronic alveolar hyperventilation?

  1. high altitude
  2. neuro disorders
  3. chronic salicylate (aspirin) toxicity

27

What are the most common causes of acute alveolar hyperventilation?

  1. pain/anxiety
  2. mechanical ventilation

28

Compensation of respiratory alkalosis takes place through the ______, which increase the excretion of bicarbonate and lower the pH toward its normal value.

kidneys

29

Compensation of respiratory alkalosis takes place through the kidneys, which increase the excretion of ______ and ______ the pH toward its normal value.

bicarbonate; lower

30

What is metabolic acidosis?

a primary addition of an acid other than CO2 leading to a reduction in bicarbonate