The Endocrine System

Question 1

What six hormones are released by the anterior pituitary gland (adenohypophysis)?

Answer 1

• Thyroid stimulating hormone
• Prolactin
• Adrenocorticotrophic hormone (corticotropin)
• Growth hormone
• Follicle-stimulating hormone
• Luteinizing hormone

Question 2

Which pituitary hormones do the following hypothalamic releasing factors act on, and how?
1- TRH
2- PIF (dopamine)
3- CRH
4- GHRH
5- GH- RIH (somatostatin)
6- GnRH

Answer 2

1- stimulates TSH
2- Inhibits PRL
3- stimulates ACTH
4- Stimulates GH
5- Inhibits GH
6- Stimulates FSH and LH

Question 3

What two hormones, actually synthesised in the hypothalamus, are released from the posterior pituitary gland (neurohypophysis) in response to appropriate stimuli?

Answer 3

Oxytocin and Antidiuretic Hormone (ADH)

Question 4

What is the most common cause of hyperpituitarsim?

Answer 4

Anterior lobe adenoma

Question 5

What are three pathologic mechanisms related to the pituitary that can result in hyperprolactinemia?

Answer 5

• Lactotroph adenoma (PRL-secreting pituitary adenoma)
• Lactotroph hyperplasia (from loss of dopamine mediated inhibition)
• Mass effect disturbing the inhibitory influence of the hypothalamus

Question 6

Antibodies for what three things are commonly found in Hashimoto thyroiditis?

Answer 6

• Antimicrosomal
• Antithyroid peroxidase
• Antithyroglobulin

Question 7

What is the most sensitive screening test for myxedema and what result would be expected?

Answer 7

Raised TSH (exception is if the hypothyroidism is due to primary hypothalamic or pituitary disease)

Question 8

What are the four metabolic functions through which PTH regulates serum calcium levels?

Answer 8

• Increase renal tubular reabsorption of calcium
• Increase activation of vit D in kidneys (augments GI calcium absorption)
• Increase urinary phosphate excretion (increasing free calcium as less bound to phosphate)
• Enhance osteoclastic activity by promoting osteoclast progenitor -> mature osteoclast

Question 9

1. Name three laboratory alterations referable to PTH or PTHrH excess
2. Which of these can be “normalised” due to secondary renal disease?

Answer 9

1. Hypophosphatemia, increased urinary excretion of calcium and phosphate
2. Phosphate (retention)

Question 10

What are the functions of the four main cell types of the islets of Langerhans?
1. beta cells
2. alpha cells
3. delta cells
4. pancreatic polypeptide cells

Answer 10

1. insulin - regulates glucose utilisation (and reduces blood glucose levels)
2. glucagon - stimulates glycogenolysis (hence increases blood glucose)
3. somatostatin - suppresses insulin and glucagon release (and growth hormone)
4. pancreatic polypeptide - several GI effects e.g. stimulation of secretion of gastric and intestinal enzymes and inhibition of intestinal motility

Question 11

Why can many acute stresses, such as severe infections, burns or trauma lead to transient hyperglycaemia?

Answer 11

Causes the secretion of hormones, e.g. catecholamines and cortisol, that oppose the action of insulin

Question 12

What are the four components of metabolic syndrome?

Answer 12

• Obesity
• Hyperglycaemia
• Increased serum cholesterol and triglycerides
• Hypertension

Question 13

What three types of steroids (with examples) are synthesised in the adrenal cortex?

Answer 13

• Glucocorticoids (cortisol)
• Mineralocorticoids (aldosterone)
• Sex steroids (oestrogen’s and androgens)

Question 14

What does the adrenal medulla synthesise?

Answer 14

Catecholamines, mainly adrenaline