L29 and L30 Acid-Base Balance

Question 1

What are the normal pH ranges in the body?

Answer 1

7.35-7.45

Question 2

What pH range is compatible with life?

Answer 2

6.8-8.0

Question 3

Which of the following is significantly affected by changes in pH?

A) Nerve excitability
B) Enzyme activity
C) Potassium homeostasis
D) All of the above

Answer 3

D) All of the above

Question 4

Disorientation, coma and death are results of decreased CNS activity.

Is this suggestive of acidosis or alkalosis?

Answer 4

Acidosis

Acidosis causes decreased CNS activity

Question 5

Pins and needles and muscle twitching are potential consequences of:

A) Acidosis
B) Alkalosis
C) Both A and B
D) Neither A nor B

Answer 5

B) Alkalosis

These are signs of increased CNS activity, which is caused by alkalosis

Question 6

How can changes in pH affect enzyme activity?

Answer 6

Changing the R-group charge of an AA can cause a change in shape.An enzyme’s shape is vital to functioning

Question 7

Acidosis causes:

A) ↑ secretion of H+
B) ↑ secretion of K+
C) ↓ secretion of H+
D) ↓ secretion of K+
E) Both A and B
F) Both A and D
G) Both B and C

Answer 7

F) Both A and D

Acidosis: ↑ secretion of H+ results in ↓ secretion of K+, leading to HYPERkalaemia

Question 8

Alkalosis causes:

A) ↑ secretion of H+
B) ↑ secretion of K+
C) ↓ secretion of H+
D) ↓ secretion of K+
E) Both A and B
F) Both A and D
G) Both B and C

Answer 8

G) Both B and C

Alkalosis: ↓ secretion of H+ results in ↑ secretion of K+, leading to HYPOkalaemia

Question 9

Acidosis results in:

A) Increased CNS activity
B) Hypokalaemia
C) Reduced enzyme activity
D) All of the above

Answer 9

C) Reduced enzyme activity

Question 10

How can intake of protein affect pH?

Answer 10

↓ pH

Phosphorus and sulphur in proteins are converted into strong acids: phosphoric and sulphuric.

Question 11

Does fruit digestion yield release of acids or bases?

Answer 11

Bases

Question 12

Anaerobic glycolysis results in what change to pH?

Answer 12

↓ pH

Anaerobic glycolysis produces lactic acid (weak acid)

Question 13

What is the quickest mechanism that reverses pH changes?

Answer 13

Blood buffers (takes seconds)

Question 14

Which acid-base mechanism takes minutes to reverse a change in pH?

Answer 14

Respiratory compensation

Question 15

Which acid-base mechanism takes hours to days for it to reverse a change in pH?

Answer 15

Renal compensation (takes hours to days)

Question 16

True or false: A buffer is a weak acid or base

Answer 16

True

Buffers absorb protons or conjugate bases. Blood buffering is highly effective

Question 17

What is the major blood buffer?

Answer 17

Bicarbonate

Question 18

In addition to bicarbonate, what are the other blood buffering systems?

Answer 18

Haemoglobin

Plasma proteins

Phosphate

Question 19

True or false: Phosphate is a good urinary buffer

Answer 19

True, because there is little reabsorption

Question 20

When can respiratory compensation NOT contribute to restoration of pH balance?

Answer 20

When the pH change is due to respiratory disease

Buffers and renal compensation become very important

Question 21

What can the kidneys regulate to compensate for changes in pH?

Answer 21

Bicarbonate reabsorption

Proton secretion

Question 22

In respiratory compensation, regulation of which substance reverses the pH change?

Answer 22

Carbon dioxide

Question 23

In acidosis:

A) Plasma H+ is ↑
B) Less HCO3 is filtered by the kidneys
C) Renal H+ secretion increases
D) All of the above

Answer 23

D) All of the above

Question 24

Why do the kidneys filter less bicarbonate in acidosis?

Answer 24

Bicarbonate buffers the excess acid, therefore you want more of it in the blood

Question 25

What substances buffer acid in urine?

Answer 25

Phosphate and ammonia

Question 26

Why is acid buffered in urine?

Answer 26

Buffers mop up protons in urine, helping maintain the H+ gradient. This allows more H+ to be pulled into the urine and raise the pH of the blood in acidotic conditions

Question 27

True or false: Phosphate is produced from glutamine metabolism

Answer 27

False

Ammonia is produced from glutamine metabolism

Question 28

True or false: Production of ammonia is up-regulated during acidosis

Answer 28

True

Question 29

What is the difference between compensation and correction (referring to pH balance)?

Answer 29

Compensation:

• Starts immediately
• Corrects pH change only
• PCO2 and HCO3 sacrificed to restore pH

Correction:
- Complete restoration of pH, PCO2 and HCO3

Question 30

True or false: Respiratory causes of pH change are normally associated with CO2, while metabolic causes are normally associated with HCO3

Answer 30

True

Question 31

What is the uncompensated result of respiratory acidosis?

Answer 31

↑ CO2

↓ pH

↑ HCO3 (but within normal limits)

Question 32

What is the result of respiratory acidosis with metabolic compensation?

Answer 32

↑ CO2

↑ HCO3 (outside normal limits)

Question 33

What are the clinical causes of respiratory acidosis?

Answer 33

Obstructive respiratory disease (emphysema)

Pulmonary oedema

Drug-induced respiratory depression (opiates)

Neuromuscular conditions

Question 34

What are the clinical causes of respiratory alkalosis?

Answer 34

Anxiety, fear

Pain

Aspirin poisoning

High altitude

Question 35

What are the clinical causes of metabolic acidosis?

Answer 35

Diabetic ketoacidosis

Diarrhoea (high excretion of HCO3)

Heavy exercise (↑ lactic acid)

Renal failure (↓ secretion of protons)

Question 36

What are the clinical causes of metabolic alkalosis?

Answer 36

Overdose of antacids

Vomiting (loss of HCl)