Endocrinology Intro

Question 1

What is the definition of a hormone?

Answer 1

Hormones are chemical messengers that travel via the bloodstream

Question 2

Describe the role of the ‘biological clock’

Answer 2

• Melatonin/CBT/cortisol all releases id in circadian rhythm.
• Biological clock is a small group of neurons in the suprachiasmatic nucleus
• cues from environment (e.g light, temperatur) keep body on 24h cycle

Question 3

How does ADH regulate body osmolality?

Answer 3

• Normal blood osmolality is 275-295mmOsm/kg
• High blood osmolality detected by osmoreceptors in hypothalamus causing release of ADH from the posterior pituitary as well as stimulating thirst. Therefore only small volumes of concentrated urine are lost.
• ADH stimulates water reabsorption in the kidney
• Low blood osmolality has the opposite effect

Question 4

What are the major endocrine tissues and what do they release?

Answer 4

Heart releases ANP and BNP
Liver releases IGF1
Stomach releases gastrin and gherkin
Placenta releases inhibin, placental lactogen
Kidney releases erythropoietin, renin, calcitriol
Adipose releases leptin

Question 5

What are some similarities in nervous system communication and endocrine communication?

Answer 5

• Both neurons and endocrine cells can be depolarised and both secrete substances
• some molecules can act as hormones or neurotransmitters

Question 6

What is the role of hormone transporters in the blood?

Answer 6

-only free form of a hormone is biologically active

carrier proteins:

• increase solubility of hormone in plasma
• increase half life
• readily accessible reserve

Question 7

What class of hormones are Luteinizing hormone, Follicle stimulating hormone, Thyroid stimulating hormone?

Answer 7

Glycoproteins

• Large protein molecules
• Often made up of subunits
• Carbohydrate side chain
• All water soluble

Question 8

What are the steroid hormones?

Answer 8

• All derived from cholesterol.
• Steroidogenic tissues convert cholesterol to different hormones
• Cortisol/Aldosterone/Testosterone/Progesterone
• All Lipid soluble

Question 9

What are some polypeptide hormones?

Answer 9

• Largest group

• Insulin
• Glucagon
• Growth hormone
• All water soluble

Question 10

What are some amino acid derivative hormones?

Answer 10

• Synthesised from aromatic amino acids
• Adrenaline/noradrenaline (tyrosine)
• Noradrenaline (tyrosine)
• Thyroid hormones (tyrosine)
• Melatonin (tryptophan)
• Adrenal medulla hormones water soluble
• Thyroid hormones lipid soluble