Endocrine & GIT

Question 1

Antidiuretic hormone (vasopressin/ ADH) is released from the pituitary in response to hypothalamic releasing hormone?

Answer 1

False. ADH is released from pituitary when osmolarity of extracellular fluid rises or if blood volume or blood pressure falls. It is produced in supraoptic nucleus of hypothalamus.

Question 2

ADH is

Answer 2

a peptide; causes water reabsorption from distal renal tubules and collecting ducts..
Increases peripheral resistance through arteriolar constriction which helps to maintain BP.

Question 3

Instances where hypokalaemia can occur

Answer 3

Primary: e.g. Conn’s (excess of adrenal hormones- aldosterone- cause hypokalemia).

Acquired: e.g. Salbutamol therapy (moves K+ intracellularly).

Question 4

High level of calcium is seen after injection of gland extracts from anterior pituitary?

Answer 4

True

Question 5

Histamine receptors in the stomach can be pharmacologically stimulated without affecting those in the lungs?

Answer 5

True

Question 6

Which components of bows gas is flammable?

Answer 6

Methane (30%)

Hydrogen (44%)

Question 7

Main types/ classes of hormones

Answer 7

Peptides- synthesised in nucleus, stored in granules, released by exocytosis. e.g. growth hormone. Act via 2nd messengers.

Amides- synthesised in neoplasm, stored in granules. Sub-classified into catecholamines (act at cell membranes by 2nd messengers), and thyroid hormones (bind directly with nucleus receptors to stimulate transcription).

Steroids- synth from cholesterol, released without storage. Lipid soluble –> enter cytoplasm, bind w/ protein receptors, then enter nucleus to stimulate transcription.

Question 8

What are the 4 risk factors predicting risk of PONV?

Answer 8

Female gender.
Non-smoking.
Post-op opioids use.
Previous history of PONV, or motion sickness.

Presence of 0, 1, ,2, 3, or all 4 factors; predicted probability of PONV would be 10%, 21%, 39%, 61%, or 78% respectively.
Ondansetron will prevent PONV in 26% of at risk group.

Question 9

Why does rectal temperature vary?

Answer 9

Due to presence of gut flora, faeces, and variable blood flow from lower limbs.

Question 10

Explain stimulation for gastric acid secretion

Answer 10

3 phases:
- Cephalic. Mediated by vagus –> ACh release at basolateral membrane of parietal cells. 50% of secretions.

• Gastric. Initiated by antral distension by presence of food –> gastrin release –> stimulates histamine release from gastric cells –> HCl from parietal.
• Intestinal. Gastrin release triggered by presence of food in duodenum; activate pyloric sphincter to reduce gastric emptying.