Adrenal Function

Question 1

adrenal glads function

Answer 1

part of the endocrine system–> contributes to homeostasis and regulates stress, ion balance (NaCl, K+, H2O) and blood pressure regulation

the adrenal cortex = produces steroids
the adrenal medulla = catecholamines

Question 2

adrenal medulla

Answer 2

made of neuronal cells called chromaffin cells which produce neurohormones
or found in groups of cells = ganglia

the CNS/spinal cord sends a signal to the medulla which activates chromaffin cells
–> release of epinephrine (neurohormone)
–> epinephrine in the blood circulation
–> travels to target tissues to activate signalling cascade

Question 3

medulla function

Answer 3

secretes catecholamines
- amine hormones
- adrenaline (epinephrine), noradrenaline (norepinephrine) and dopamine

–> provides acute response as it equips body with adrenaline
–> initiate fight or flight response

Question 4

adrenaline axis

Answer 4

stress activates hypothalamus
–> nerves signal spinal cord
–> signals adrenal medulla
–> medulla secretes adrenaline

Question 5

adrenaline effect

Answer 5

medulla : short term
- glycogen –> glucose [increase in blood glucose conc]
- Increase in Blood Pressure
- Inc in Breathing Rate
- Inc in metabolic rate
- alertness Inc, Dec in digestive/kidney activity

cortex : long term
- mineralcorticoids
- –>retention of H2O and Na+ by kidneys
- –> Inc Blood volume and blood pressure
- glucocorticoids
- –> gluconeogenesis (protein/fats = glucose)
- –> immune system and wound healing decrease
- alertness Inc, Dec in digestive/kidney activity

Question 6

adrenal cortex steroid hormones and zones

Answer 6

zona glomerulosa
* mineralcorticoids = minerals e.g. aldosterone

zona fasiculata
* glucocorticoids = regulate blood glucose levels e.g. cortisol

zona reticularis
* progesterone/androgens/estrogen = sex hormones
* mostly androgens especially DHEA

Question 7

renin-angiotensin-aldosterone

Answer 7

aldosterone = a mineralcorticoid that helps salt/electrolyte balance

1) system activated when dec in blood pressure and volume
2) kidney releases renin in the blood
3) angiotensinogen (precursor) produced by the liver detects renin in the blood and converts to angiotensin I (intermediate)
4) it converts to angiotensin II (final/active product) when it meets ACE (angiotensin-converting enzyme) in the lung

angiotensin II :
1) triggers your adrenal glands to release aldosterone
–> attaches to receptors on kidney and initiates transcription for NaCL transporters –> for uptake of NaCl and H2O into blood/back into the system
2) vasoconstriction = increase blood pressure (ang II)

Question 8

aldosterone mechanism

Answer 8

1) aldosterone diffuses into cell and binds with receptor
2) HRC (hormone receptor complex) initates transcription in nucleus
3) synthesises ion channels and Na+/K+ pumps
4) attach to plasma membrane (of the distal tubules of kidney) to facilitate NaCl uptake OR aldosterone induced proteins can modify the existing proteins
5) K+ enter tubular lumen to balance electrolytes
6) Inc blood pressure + homeostasis

Question 9

adrenal androgens

Answer 9

• different to androgens in gonads
• minimal role on stress
• weak adrenegic activity/ low physiological effect (DHEA = weak function, precursor to progesterone and estrogen)

mechanism
–> similar to the HPA axis
signal comes in, CRH from hypothalamus–> anterioir pituitary –> ACTH –> adrenal cortex –> zona reticularis = androgens

function
males = prostate growth + masculinsation (deep voice + hair growth) + libido
femaless = hair growth+ sebum prouduction + libido

hair = auxillary (armpits), facial and pubic

Question 10

medulla vs cortex

Answer 10

medulla = catecholamines
–> acute stress response
–> amine hormones (synthesised by tyrosine)
–> glycogen to glucose

cortex = steriod hormones e.g. mineralcorticoids, glucocorticoids, and androgens
–> gluconeogenesis
takes longer during stress because the steroid hormones need to initiate transcription and translation of gluconeogenic enzymes