L9: Acid/Base Physiology

Question 1

What 3 mechanisms regulate [H+] concentration (acid/base homeostasis) in the body?

Answer 1

Buffers (fastest) - FIRST LINE OF DEFENSE
Respiratory compensation
Renal compensation (slowest)

Question 2

Range of blood pH

Answer 2

7. 4

7. 35 acidic - 7.45 alkalotic

Question 3

An increase in pH will _____ [H].

Answer 3

Decrease (more alkaline)

Question 4

What is a volatile acid?

Answer 4

Gas - think of CO2 from the lungs; creates H+ ions

Question 5

Basic Henderson-Hasselbalch equation for pH

Answer 5

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

Question 6

When [A]=[HA], then

Answer 6

pH = pK

Question 7

Describe H affinity and the pK of strong acids

Answer 7

Lower affinities for H ions which dissociate easily from conjugate base
Lower pKs

Question 8

Describe H affinity and the pK of weak acids

Answer 8

Higher affinities for H ions which do not dissociate as easily from conjugate base
Higher pKs

Question 9

The effectiveness of a buffer (FIRST LINE OF DEFENSE) is proportional to its:

Answer 9

Concentration

pK

Question 10

Bicarbonate buffer system is most important in the ____. How many pH units from pK results in the most effective buffering?

Answer 10

ECF

Most effective buffering is +/- ONE pH unit from pK

Question 11

List the buffers of the blood in order of importance (most responsibility)

Answer 11

1. Bicarb
2. Hemoglobin
3. Proteins
4. Phosphate

Question 12

List the buffers of the ICF in order of importance

Answer 12

1. Proteins, phosphate

2. Bicarb

Question 13

What is the mean and range of PCO2

Answer 13

Mean: 40
Range: (acid) 45-35 (alk)

Question 14

What is the mean and range of HCO3

Answer 14

Mean: 24
Range: (acid) 22-26 (alk)

Question 15

What is the pK of HCO3?

Answer 15

6.1

Question 16

HH equation with values for bicarbonate buffer system (blank + filled in with constants)

Answer 16

pH = pK + log [HCO3-]/(0.03 x PCO2)
pH = 6.1 + log 24/(0.03 x 40)