Endocrine system 2

Question 1

Where is parathyroid hormone (PTH) secreted from and what does it do?

Answer 1

Parathyroid hormone is secreted from the parathyroid glands located on the posterior surface of the thyroid gland

PTH acts to increase plasma Ca2+ levels, opposing the effects of calcitonin - antagonistic hormone action

Question 2

Where is calcitonin produced and what does it do? (2)

Answer 2

Produced by parafollicular C cells

Acts to reduce plasma Ca2+ levels

Question 3

Where is the adrenal gland located?

Answer 3

On top of each kidney, the right is slightly lower due to the liver

Question 4

What does the adrenal gland produce? (3)

Answer 4

Adrenaline - catecholamine
Noradrenaline - catecholamine
Dopamine - small amount

Question 5

What are 3 adrenal steroid hormones?

Answer 5

Mineralocorticoids (aldosterone)
Glucocorticoids (cortisol)
Weak androgens (DHEA)

Question 6

What cells are in the adrenal medulla and what’s produced in the adrenal medulla?

Answer 6

Chromaffin cells - modified postganglionic sympathetic neurone (axonless)

Adrenaline and noradrenaline (boosts immune system)

Question 7

What are the 3 zones of the adrenal cortex?

Answer 7

(Capsule encompassing organ)
Zona glomerulosa
Zona Fasciculata
Zona Reticularis
(Medulla (chromaffin cells))

Question 8

What is the main mineralocorticoid in the zona glomerulosa and what does it do (2)?

Answer 8

Aldosterone

Regulates Na+ and K+ balance
Part of the renin-angiotensin-aldosterone system

Question 9

What is the main mineralocorticoid in the zona fasciculata and what does it do (2)?

Answer 9

Cortisol

Adaptation to stress
Regulates glucose metabolism, also protein and fat

Question 10

What is the main mineralocorticoid in the zona reticularis and what does it do?

Answer 10

Mainly weak androgens (DHEA)

Testosterone - 99% male, 50% female

Question 11

Which hormone gives negative feedback?

Answer 11

Cortisol

Question 12

Describe the stages in the hypothalamus-pituitary-adrenal axis: (7)

Answer 12

Hypothalamus
Corticotropin-Releasing Hormone (CRH)
Anterior pituitary
Adrenocorticotropic hormone (ACTH)
Adrenal cortex
Cortisol (exogenous glucocorticoids) - feedback
Target cell response

Question 13

Explain a typical diurnal variation of plasma cortisol?

Answer 13

Cortisol peaks in the early morning and declines until we sleep - sleep wake cycle

Question 14

What are the pancreas’ exocrine and endocrine functions?

Answer 14

Exocrine - digestive enzymes to break down carbs, proteins and lipids in the chyme
Endocrine - islet of Langerhans

Question 15

Where is the pancreas located?

Answer 15

Close to the large intestine, under the liver, behind the stomach

Question 16

What are the islets of Langerhans? (2)

Answer 16

Endocrine cells in clusters scattered throughout the pancreas

Small but require large blood supply

Question 17

What do islets of Langerhans look like under a microscope?

Answer 17

Paler regions in circular shape

Question 18

What are islets made up of? (3)

Answer 18

Alpha cells - 30/40% - glucagon
Beta cells - 50/60% - insulin
Delta cells - 5/10% - somatostatin

Question 19

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

Answer 19

Peptide hormone
Synthesized in Beta cells
Main physiological regulator in blood glucose levels

Question 20

What does insulin promote (3)?

Answer 20

Promotes Growth and development
Promotes cellular uptake of K+
Promotes uptake and utilisation of glucose in muscles

Question 21

What is the main insulin action?

Answer 21

Reduce blood glucose by uptaking glucose in muscle, the liver and adipose tissue via GLUT-4

Question 22

Where is glucagon synthesised and why is it produced?

Answer 22

Glucagon is synthesised in alpha cells and is a peptide hormone

Stimulated by LOW blood glucose

Question 23

What does glucagon stimulate? (3)

Answer 23

Hepatic glycogenolysis
Hepatic gluconeogenesis
Lipolysis

All raise blood glucose

Question 24

What are Gonads? (3)

Answer 24

Testes - testosterone
Ovaries - progesterone
Placenta - oestrogen and progesterone

Question 25

What is a synergistic hormone action provide one example?

Answer 25

Multiple hormones acting with other hormones to produce an enhanced response

Example: Glucagon, adrenaline, cortisol to increase blood glucose

Question 26

What is a permissive hormone response and an example?

Answer 26

Presence of one hormone allows a second hormone to act

Example: Prolactin (milk) to allow oxytocin action (milk let down)

Question 27

What is an antagonistic hormone response and an example?

Answer 27

Effects of hormones oppose each other

Example: Insulin and glucagon