physiological hormone axis

Question 1

What hormones does the anterior pituitary gland release?

Answer 1

Thyroid Stimulating Hormone (TSH)
Adenocorticotrophic Hormone (ACTH)
Follicle Stimulating Hormone (FSH) and luteinising hormone (LH)
Growth hormone 
prolactin

Question 2

What hormones does the posterior pituitary release?

Answer 2

oxytocin 
Antidiuretic hormone (ADH)

Question 3

Describe the thyroid axis

Answer 3

The hypothalamus releases TRH, this stimulates the anterior pituitary to release TSH. This stimulates the thyroid gland to release T3 and T4

Question 4

Describe the adrenal axis

Answer 4

The hypothalamus releases corticotrophin release hormone (CRH), anterior pituitary releases ACTH. This stimulates the adrenal gland to release cortisol

Question 5

What are cortisol’s actions in the body?

Answer 5

inhibits immune system
inhibits bone formation
raises blood glucose
increases metabolism 
increases alertness

Question 6

Describe the growth hormone axis

Answer 6

GHRH is released from the hypothalamus, the stimulates GH release from the anterior pituitary.
Growth hormone stimulates the release of insulin-like growth factor (IGF-1) from the liver

Question 7

What are the main functions of growth hormone?

Answer 7

stimulates muscle growth
increases bone density and strength
stimulates cell regeneration and reproduction
stimulates growth of internal 
organs

Question 8

Describe the parathyroid axis

Answer 8

PTH is released from the 4 parathyroid glands in response to low serum calcium, low magnesium and high serum phosphate. its role is to increase the serum calcium concentration

Question 9

What are the 3 main effects of PTH?

Answer 9

increases the number and activity of osteoclasts - bone reabsorption
Increases calcium reabsorption by the kidneys
Stimulates the kidneys to convert vitamin D3 into calcitriol to promote calcium absorption in the small intestine

Question 10

Describe renin secretion

Answer 10

Renin is secreted by the juxtaglomerular cells that sit in the afferent arterioles. Low BP leads to renin release. Renin is an enzyme that converts angiotensinogen(released by liver) into angiotensin 1. Angiotensin 1 converts to angiotensin II in the lungs with the help of ACE in the lungs

Question 11

Describe the action of angiotensin II

Answer 11

causes vasoconstriction to increase BP

Also stimulates the release of aldosterone from the adrenal glands

Question 12

What sort of hormone is aldosterone?

Answer 12

mineralocorticoid steroid

Question 13

What are the actions of aldosterone?

Answer 13

Increases Na reabsorption from the distal tubule
Increases potassium secretion from the distal tubule
Increases Hydrogen secretion from the collecting ducts

Sodium reabsorption in the kidneys leads to increased intravascular volume and raised BP