Phase 1 endocrinology

Question 1

The thyroid hormones: what are they formed from? where are they produced? What do they do?

Answer 1

Thyroxine and triiodothyronine are derived from tyrosine amino acid.
produced in the follicular cells of the thyroid gland.
regulates metabolism, growth and development.
(phase 1 lecture)

Question 2

How does testosterone reach its target cell?

Answer 2

It is lipid soluble (like all steroids) so it passes through the cell membrane and binds to its receptors.

Question 3

Growth hormone - what is it formed from, where is it produced, what does it do?

Answer 3

GH is a peptide hormone produced in the anterior pituitary, which regulates growth and metabolism.

Question 4

Vasopressin - what is it formed from, where is it produced, what does it do?

Answer 4

Peptide hormone (=ADH), produced in hypothalamus and released in the supraoptic nuclei of the posterior pituitary, regulates water secretion into the urine.

Question 5

What type of hormone is oxytocin, where is it produced and what does it do?

Answer 5

Peptide hormone. Produced in the paraventricular nuclei of the posterior pituitary, causes expression of milk from the glands of the breasts to the nipples, promotes onset of labour. It is present in males but function unclear.

Question 6

How is plasma concentration measured?

Answer 6

In osmolality - mOsmol/kg. Measured by an osmometer which uses freezing point.
(phase 1 lecture)

Question 7

What happens in syndrome of inappropriate ADH secretion?

Answer 7

Too much ADH is secreted. This is common and can be life-threatening.

Question 8

Describe the blood supply to the thyroid gland.

Answer 8

External carotid branches:

Superior and inferior thyroid arteries.

Question 9

How are thyroid hormones synthesised?

Answer 9

The thyroid synthesises T3, which acts at the cellular level, and T4, which is the prohormone (KCM).
MIT (1T) +DIT (2T) = T3
DIT (2T) +DIT (2T) =T4

Question 10

What type of hormone is thyroid stimulating hormone, where is it made and what does it do?

Answer 10

Glycoprotein hormone. Anterior pituitary. Stimulates growth and activity of the thyroid follicular cells via a G-coupled TSH membrane receptor.

Question 11

What are T3 and T4 bound to in blood?

Answer 11

Albumnin (lecture)

Question 12

Is t3 or t4 more abundant?

Answer 12

T4 is more abundant bound to albumin but FREE t3 is more abundant.

Question 13

Give 3 symptoms of hypothyroidism

Answer 13

Intolerance to cold
Fatigue
Constipation
Late: weight gain.

Question 14

Give 3 symptoms of hyperthyroidism.

Answer 14

Heat intolerance
Diarrhoea
Weight loss
Insomnia