Adrenal Glands Physiology Flashcards
What are the hormones secreted by the zona glomerulosa of the adrenal gland?
Mineralocorticoids (aldosterone)
What is the function of aldosterone?
Potassium, sodium, and water homeostasis
What are the hormones secreted by the zona fasciculata of the adrenal galnd?
Glucocorticoids (cortisol)
What is the function of glucocorticoids like cortisol?
Glucose homeostasis plays a role in the metabolism of proteins and lipids and in adaptation to stress
What hormones are secreted from the zona reticularis of the adrenal gland?
Sex steroids (androgens)
What hormones are secreted by the medulla of the adrenal gland?
Catecholamines
What are examples of catecholamines secreted by the medulla of the adrenal gland?
Norepinephrine
Epinephrine
Dopamine
What are the three different classifications of the adrenocortical hormones?
MIneralocorticoids
Glucocorticoids
Sex hormones
What is an example of sex hormones?
DHEA –> an androgen (male sex hormone)
What type of hormone is aldosterone?
A steroid hormone (mineralocorticoid)
What regulates aldosterone?
Renin-angiotensin system
Where is renin secreted and in response to what?
Renin is secreted from the kidneys in response to variations in BP and volume and plasma sodium and potassium levels
What is the role of renin?
Converts angiotensinogen into angiotensin I
What type of hormone is cortisol?
A steroid horome (glucocorticoid)
How are the levels of cortisol regulated
They rise and fall naturally through-out the day
When are cortisol levels the highest and when are they the lowest?
Lowest: late at night
Highest: early in the morning
What is DHEA?
Precursor for androgen
What is the function of DHEA?
Produces male hormones in women and female hormones in men to keep the effects of the dominant sex hormones in balance
What is the adrenal medulla?
A modified sympathetic prevertebral ganglion that releases epinephrine and norepinephrine into the blood in response to sympathetic stimulation
What is the functional unit of the adrenal medulla?
The chromaffin cell, which functions as an NE cell
What does epinephrine activate have an effect on?
b-adrenoreceptor and a-adenoreceptors
What is the effect of adrenaline on b-adrenoreceptors?
Vasodilation
Tachycardia
Insulin resistance
What is the effect of the activation of a-adrenoceptors?
Vasoconstriction
Which catecholamine acts only om the a-adrenoceptor?
Noradrenaline
What are the effects of androgens when bound to androgen receptors?
Hair (pubic and axillary)
Libido (especially in females)
What are the effects of cortisol when bound to glucocorticoid recepors?
Metabolic regulation
Immunomodulation
Cardiovascular regulation
CNS actions
What is the effect of b-LPH?
Pigmentation
What is the Aldosterone secretion pathway like?
- Decrease in plasma volume or increase in plasma K+
- Increase of plasma angiotensin II
- Increase of adrenal secretion from the adrenal cortex
- Increase the concentration of plasma aldosterone
What is the effect of increased plasma aldosterone on the cortical collecting ducts?
Increased sodium reabsorption –> Decreased sodium excretion
Increased potassium secretion –> Increased potassium excretion
What are the regulation of secretion of mineralocorticoids like aldosterone?
- The levels of potassium and sodium in the blood
- The RAAS
- ACTH (to a lesser extent)
What regulates glucocorticoids and androgen ?
Regulated by hypothalamic-pituitary system
What is the hypothalamic-pituitary system?
A negative feedback system, one of the most important elements of homeostasis, maintains a steady internal biochemical and physiological balance in the body
What does the HPA axis regulate?
Adjusts cortisol levels according to the need of the body, under normal and stressed conditions via ACTH
Where is ACTH secreted from?
Secreted from the pituitary gland in response to the orders from the hypothalamus and travels in the bloodstream to the adrenal cortex
In relation to stress what kind of glands are adrenal glands?
They are anti-stress glands
What is the function of the cortisol during stress conditions?
- Needs to provide more blood glucose
- Mobilize fats and proteins for a back-up supply of glucose
- Modify immune reactions, heartbeat, blood pressure, brain alertness and nervous system responsiveness