Endocrinology

Question 1

What is endocrinology?

Answer 1

The study of the endocrine system, including hormones, endocrine glands/tissues, and associated diseases.

Question 2

What are the three classes of hormones?

Answer 2

Peptide hormones, steroid hormones, and amino acid-derived hormones.

Question 3

Give an example of each hormone class.

Answer 3

Peptide: Insulin; Steroid: Oestrogen; Amino acid-derived: Thyroid hormone (T3, T4).

Question 4

What is a key characteristic of peptide hormones?

Answer 4

Water-soluble, not orally active, rapid onset, short half-life.

Question 5

How do peptide hormones act?

Answer 5

Bind to membrane-bound receptors, often G-protein coupled or tyrosine kinase.

Question 6

What are steroid hormones derived from?

Answer 6

Lipids, especially cholesterol.

Question 7

How do steroid hormones travel in the blood?

Answer 7

Bound to plasma proteins due to their lipophilic nature.

Question 8

Where do steroid hormones act?

Answer 8

On intracellular nuclear receptors to affect gene transcription.

Question 9

Why are steroid hormones synthesized on demand?

Answer 9

Their lipophilicity makes storage difficult, so they are made as needed.

Question 10

What are the thyroid hormones?

Answer 10

T3 (tri-iodothyronine) and T4 (thyroxine/tetraiodothyronine).

Question 11

Which thyroid hormone is more active?

Answer 11

T3 is the active form; T4 is more abundant and a precursor.

Question 12

What is thyroxine-binding globulin (TBG)?

Answer 12

A protein that binds and transports T4 and T3 in the blood.

Question 13

What percentage of thyroid hormones are bound in the blood?

Answer 13

About 99% are bound to proteins like TBG, TBPA, and albumin.

Question 14

What is the primary effect of thyroid hormones?

Answer 14

To increase basal metabolic rate.

Question 15

How do thyroid hormones affect metabolism?

Answer 15

Increase mitochondria, enzyme activity, carbohydrate/lipid/protein metabolism.

Question 16

What is the hypothalamic-pituitary axis?

Answer 16

A regulatory pathway: hypothalamus releases ‘releasing’ hormones, stimulating the anterior pituitary to release ‘trophic’ hormones.

Question 17

Which hormones are released by the posterior pituitary?

Answer 17

Antidiuretic hormone (ADH) and oxytocin.

Question 18

Which hormones are released by the anterior pituitary?

Answer 18

GH, TSH, ACTH, FSH, LH, and prolactin.

Question 19

Where is the thyroid gland located?

Answer 19

In the neck, surrounding the larynx.

Question 20

What do parathyroid glands regulate?

Answer 20

Calcium homeostasis.

Question 21

What is the adrenal medulla responsible for?

Answer 21

Releases adrenaline and noradrenaline in response to nerve signals.

Question 22

What does the adrenal cortex release?

Answer 22

Glucocorticoids (e.g., cortisol) and mineralocorticoids (e.g., aldosterone).

Question 23

What hormone controls the adrenal cortex?

Answer 23

ACTH from the anterior pituitary.

Question 24

What are the gonads and their hormones?

Answer 24

Ovaries/testes; secrete oestrogen, progesterone, testosterone.

Question 25

What is the dual role of the pancreas?

Answer 25

Endocrine (insulin and glucagon secretion) and exocrine (digestive enzymes).

Question 26

What cells in the pancreas are endocrine?

Answer 26

Islets of Langerhans.

Question 27

How is insulin secretion controlled?

Answer 27

By blood glucose levels and parasympathetic activity.

Question 28

What is negative feedback in endocrinology?

Answer 28

End-product hormone inhibits release of upstream hormones.

Question 29

Example of negative feedback?

Answer 29

T4 inhibits TSH and TRH; cortisol inhibits ACTH and CRH.

Question 30

What causes hyperthyroidism in the UK?

Answer 30

Graves’ disease – autoimmune mimicry of TSH.

Question 31

Symptoms of hyperthyroidism?

Answer 31

Weight loss, heat intolerance, tachycardia, anxiety.

Question 32

What causes hypothyroidism in the UK?

Answer 32

Hashimoto's thyroiditis – autoimmune destruction of thyroid.

Question 33

Symptoms of hypothyroidism?

Answer 33

Weight gain, cold intolerance, fatigue, bradycardia.

Question 34

How is hyperthyroidism treated?

Answer 34

Radioactive iodine ablation, surgery, or T3/T4 synthesis inhibitors.

Question 35

How is hypothyroidism treated?

Answer 35

Levothyroxine (synthetic T4) replacement.

Question 36

Why does T4 have a longer half-life than T3?

Answer 36

T4 is more stable and less biologically active, lasting 6–8 days vs. 1 day for T3.

Question 37

What is the difference between anterior and posterior pituitary control?

Answer 37

Anterior is regulated chemically via releasing hormones; posterior by nerve signals.

Question 38

What does oxytocin do?

Answer 38

Regulates milk ejection (lactation) and promotes bonding.

Question 39

What is calcitonin?

Answer 39

A hormone from thyroid parafollicular cells that helps regulate calcium.