Endocrine System

Question 1

What is the function of ES?

Answer 1

• Responsible for control of large numbers of homeostatic variables
• Regulation of development, growth and reproduction

Question 2

Differences between endocrine and NS

Answer 2

• Endocrine response = quite slow
• NS has a localised effect, whilst hormones are exposed to most of the body in blood

Question 3

How do drugs treat ES diseases

Answer 3

Either mimic or block the actions of hormones

Question 4

Define hormone

Answer 4

chemical messengers that mediate communication by endocrine system

Question 5

Define endocrine glands

Answer 5

organs that release hormones

Question 6

What are target tissues?

Answer 6

• intended site that hormone will effect
• hormones travel through systemic circuit and bind to receptors associated with TT

Question 7

Define tropic hormones

Answer 7

don’t produce direct effects on other physiological systems. they regulate release of hormones by other endocrine organs and/or control growth and development of these organs.

Question 8

What are endocrine cells

Answer 8

Each hormone is secreted by different cell types

Question 9

Label endocrine organs

Answer 9

Question 10

What hormones does pituitary gland secrete

Answer 10

Question 11

Describe thymus gland

Answer 11

• located in thoracic cavity next to sternum
• reaches max size during childhood and declines in adulthood
• secretes many peptide hormones responsible for development of immune system

Question 12

What hormones do adrenal glands secrete

Answer 12

• Adrenal cortex: outer shell. secretes corticosteroids
• Adrenal medulla: adrenaline or noradrenaline

Question 13

What hormones does pancreas secrete?

Answer 13

Insulin: peptide hormone secreted by beta-cells of pancreas. insulin reduces blood glucose levels by promoting its uptake by muscle and fat cells

Glucagon:peptide hormone secreted by alpha-cells of pancreas. Anatagonist to insulin. released by hypoglycaemia. increases BG levels by stimulating breakdown of glycogen and release of glucose from liver

Question 14

What other organs have cells that have endocrine functions?

Answer 14

brain, digestive tract, heart and kidney

Question 15

How do hormones use carrier proteins?

Answer 15

• After release, some bind to a carrier protein and are transported in blood as complexes
• Hormone is inactive in complex. Has to dissociate to bind to receptor

Question 16

Why are carrier proteins useful

Answer 16

1. Readily available supply of hormone in circulation
2. Act as a buffer and smooth out spikes in hormone secretion
3. Make hormone less likely to be metabolised by enzymes in blood, liver, kidney…

Question 17

What are peptide hormones

Answer 17

consist of chains of amino acids
E.g: insulin, GH, calcitonin

Question 18

How are peptide hormones synthesised

Answer 18

1. Synthesised in rough ER of their gland
2. Go to golgi apparatus for further processing
3. Packaged in membrane bound secretory vesicles. Stored here until release.
4. Secreted by exocytosis into adjacent capillaries once exposed to certain trigger.

Question 19

How do peptide hormones bind?

Answer 19

1. Circulate in free state
2. Enter extracellular space and bind to specific receptors for target cell
3. Receptor is a membrane spanning protein w/ binding site on ECS side
4. Binding triggers conformational change of receptor, which triggers response in target cell

Question 20

What are amine hormones

Answer 20

Structural derivatives of tyrosine (amino acid)
E.g: catecholamines

Question 21

How is noradrenaline synthesised in most catecholamine secreting cells?

Answer 21

1. Tyrosine -> dihydroxyphenylalanine (L-DOPA) -> dopamine (DA)
2. DA transported into mem-bound secretory vesicles, where enzymes that convert to noradrenaline are located
3. Noradrenaline stored in vesicles until release by exocytosis

Question 22

What happens to noradrenaline in adrenal medulla?

Answer 22

• Noradrenaline transported back to cytoplasm
• Acted on by an ezyme only found there
• Produces adrenaline
• Goes back to vesicles for storage and secretion

Question 23

Describe the release of amine hormones

Answer 23

• After release, amine hormones circulate in free state, enter ECS and bind to adrenergic receptors on TT
• Normal conformational change…