L25 - adrenal function Flashcards
where are the adrenal glands located
above kidneys
what does adrenal cortex secrete
steroid hormones (glucocorticoids , mineralocorticoids
what does adrenal medulla secrete
catecholamines (NA, A , dopamine)
name the 2 corticosteroids
glucocorticoids , mineralocorticoids
which part of the adrenal gland is part of the HPA axis
cortex
list functions of corticosteroids
involved in: metabolism blood pressure and vol nutrient uptake and storage fluid and electrolyte balance inflammatory and immune response
name the layers of the cortex
- zona reticularis (inner, above medulla)
- zona fasiculata (middle)
- zona glomerulosa (outer of cortex)
what is secreted from the zona glomerulosa
mineralocorticoids (aldosterone)
where is aldosterone synthesised
zona glomerulosa - outer layer of the adrenal cortex
what is made and secreted from the zona fasiculata
cortisol and androgens
what is the thickest layer of the adrenal cortex
zona fasiculata (middle)
what is made and secreted from the zona reticularis
cortisol and androgens
what stimulates the adrenal medulla?
SNS impulses from hypothalamus
what surrounds entire adrenal gland
connective tissue capsule
give an example of a mineralocorticoid
aldosterone
what do steroid steroid secreting hormones contain
lipid droplets containing cholesterol
what is cortisol ?
glucocorticoid
what is aldosterone?
minerlocorticoid
function of mineralocorticoids eg aldosterone
- control of electrolyte homeostasis
what effect does aldosterone (mineralocorticoid) have on the kidney
- increases Na reabsorption
- increases K+ excretion
indirectly affects water retention and therefore blood pressure and volume
what triggers aldosterone release?
- high [k+]
- low [Na+]
- low blood volume/ pressure
- angiotensin 2
what system regulates aldosterone levels in response to low blood volume and how
renin - angiotensin system in juxtaglomerular cells
angiotensin 11 produced from this process stimulates aldosterone release from adrenal cortex
function of glucocorticoids (cortisol)
- regulates glucose metabolism
2. responds to stress
what are the effects of cortisol on target tissues?
- promotes glycogen breakdown in muscles
- promotes gluconeogenesis in liver
- promotes protein breakdown to AA
- inhibits inflammatory and immune response
what is overall effect of cortisol?
increases plasma [glucose] and [ketones]
what controls adrenal function?
- hypothalamus
2. renin angiotensin system
explain how the renin angiotensin system is involved in adrenal function
- renin converts angiotensin into angiotensin 1
- angiotensin 1 is converted into angiotensin 2 in tissues
- angiotensin 2 stimulates aldosterone release from adrenal cortex (zona glomerulosa)
explain HPA axis
- CRH released from hypothalamus to anterior pituitary
- ACTH released from anterior pituitary to adrenal cortext
- ACTH binds to zona fasiculata & reticularis
- cortisol released
what is congenital adrenal hyperplasia
disease where genetic mutations lead to lack of 1 or more enzymes involved in the production of steroid hormones
what are the effects of congenital adrenal hyperplasia
most serious - no cholesterol - no sexual differentiation
hypertension
absent/early puberty
what is Addison’s disease
acquired autoimmune destruction of adrenal gland cells
effects of Addison’s disease
- hypotension (no aldosterone)
- tiredness
- weakness
how is Addison’s disease treated
with steroid hormone administration
what is cushings syndrome
overproduction of glucocorticoids
effects of cushings syndrome
- high blood [glucose]
- weight gain (especially in face&neck)
- risk of type 2 diabetes
- muscle wasting
- reduced healing & increased bruising
usual cause of cushings syndrome?
pituitary/adrenal tumour causing excess ACTH production
