L16- Acid-Base Homeostasis

Question 1

What buffering systems are in place to try to keep balance?

Answer 1

Haemoglobin

Bicarbonate

Phosphate

Proteins

Ammonia

Misc organic acids

Question 2

Normal range of pH?

Answer 2

7.45- 7.35

Question 3

What are the sites of Acid-base metabolism

Answer 3

Lungs

Kidneys

GI tract

Liver

Question 4

What direction does the O2-Haemoglobin dissociation curve when there is increased 2,3 DPG

Answer 4

To the RIGHT

An increased concentration of BPG in red blood cells favours formation of the T, low-affinity state of hemoglobin and so the oxygen-binding curve will shift to the right.

Question 5

What direction does the O2-Haemoglobin dissociation curve when there is increased temperature?

Answer 5

To the RIGHT

Increasing temperature will weaken and denature the bond between an oxygen and a hemoglobin which in turn decreases the concentration of the oxyhemoglobin

Question 6

What direction does the O2-Haemoglobin dissociation curve when there is acidosis?

Answer 6

To the RIGHT

decrease in blood pH, will result in haemoglobin proteins releasing their load of oxygen

Question 7

What are proteins catabolised to in the Liver?

Answer 7

proteins catabolised to NH4+ and HCO3 -

Question 8

Why can Severe Liver Failure cause NH4+ toxicity

Answer 8

Because the liver uses it for the reaction:
NH4+ + CO2 –X–> Urea + H+

Therefore a build of NH4+ can cause metabolic alkalosis

Question 9

Causes of Metabolic Acidosis

Answer 9

Increased H+ formation

Acid ingestion

Reduced renal H+ excretion

Loss of bicarbonate

Question 10

Causes of Metabolic Alkalosis

Answer 10

Generation of bicarbonate by gastric mucosa

Renal generation of HCO3- in Hypokalaemia

Administration of bicarbonate

Question 11

Consequences of Metabolic alkalosis

Answer 11

K+ —> Cells and Urine
PO4 —> Cells
Respiratory Suppression

Question 12

Reasons for Respiratory Acidosis

Answer 12

1: inadequate ventilation
2: parenchymal lung disease
3: inadequate perfusion

Question 13

Reasons for Respiratory Alkalosis

Answer 13

Increased CO2 excretion due to excessive ventilation producing alkalosis

Question 14

What can lead to increase H+ formation

Answer 14

ketoacidosis, diabetic or alcoholic
lactic acidosis
poisoning
inherited organic acidoses

Question 15

What is Diabetic keto-acidosis

Answer 15

hyperglycaemia

osmotic diuresis —> to pre-renal uraemia

hyperketonaemia

increased FFA
—> all lead to acidosis

Question 16

What is Lactic acidosis ?

Answer 16

a form of metabolic acidosis due to the inadequate clearance of lactic acid from the blood

Question 17

What is meant by a high anion gap?

Answer 17

metabolic acidosis

caused generally by the body producing too much acid or not producing enough bicarbonate

Question 18

Process of acidosis in an alcoholic

Answer 18

There is NAD+ depletion (due to lack of thiamine)

Thiamine is pyruvate dehydrogenase co-factor

Inc Glycolysis for ATP production

(also another factor leading to acidosis is vomiting!)

Question 19

Does high lactate = lactic acidosis ?

Answer 19

In alkalosis
1. increased glycolysis

2. reduced O2 delivery due to shift in O2 dissociation curve
3. Lactate induced vasoconstriction
   impaired mitochondrial respiration

O2 debt due to # 2
1. further anaerobic lactate production
Hyperventilation

Question 20

status asthmaticus

Answer 20

a severe condition in which asthma attacks follow one another without pause

Question 21

What can be a cause of Reduced H+ excretion ?

Answer 21

renal tubular acidosis (kidneys fail to excrete acids into the urine, which causes a person’s blood to remain too acidic)

generalised renal failure

Question 22

What can Renal Failure lead to (ions etc)?

Answer 22

Lead to REDUCED VOLUME OF NEPHRONS

Increased bicarbonate loss

Reduced NH4+ excretion

Therefore more NH4+ to liver for urea + H+ synthesis