Case 10

Question 1

What happens to potassium levels during diabetic ketoacidosis?

Answer 1

High urine glucose in DKA induces osmotic diuresis and pulls K+ into the urine and out of the body.

At the same time, the metabolic acidosis present in

DKA pulls K+ from the intracellular space to the extracellular space.

The result is low intracellular K+, normal to high serum K+ and low total body K+.

Question 2

Which area of the eye has greatest acuity?

Answer 2

The fovea

It contains the greatest concentration of cones, each cone synapses with one bipolar cell allowing discrimination between stimulation of different photoreceptors

Question 3

Ndaba (Paul) is brought into A&E. On arrival he is unconscious and receiving chest compression.

An ECG confirms he is having an MI.

An ABG is performed and some of the results are shown:

pH 7.1 (7.35-7.45)

PaO2 9.0kPa (>10kPa)

PCO2 7.3kPa (4.7-6kPa)

HCO3 16mmol/L (22-26mmol/L)

What is the best overall interpretation of the results?

Answer 3

Metabolic and Respiratory Acidosis due to cardiogenic shock.

Question 4

How does pre-proinsulin become insulin?

Answer 4

Pre-proinsulin goes to the ER where it becomes proinsulin then moves to the Golgi apparatus where it is cleaved into C-peptide and peptides A+B (insulin)

Ribosomes produce proteins for pre-proinsulin from mRNA, in the ER this pre-proinsulin is converted into pro-insulin which is made up of 3 peptides (A, B and C). In the golgi apparatus this is then cleaved to form c-peptide and insulin (peptide A+B together). C-peptide then goes to membrane G protein whereas the insulin is secreted into the blood, travels to the liver and acts on insulin receptors.