9 Aldosterone Flashcards
main direct effects of aldosterone?
- recovery of sodium in the kidney and enhanced potassium secretion into the urine
- regulates blood volume
what 3 physical attributes of plasma can be regulated to affect the homeostasis of the blood system?
- volume
- blood pressure
- osmolarity
what comes first: thirst of sodium appetite?
thirst
what kind of cells control the ability of blood vessels to constrict/dilate?
smooth muscles around the vessels
what hormones control how much aldosterone is in the system?
- renin
- angiotensin
where is renin produced?
kidney
what is angiotensinogen?
produced by the liver; it’s the inactive form of angiotensin I; activated by interacting with renin
how is angiotensin I converted angiotensin II?
enzyme from the lungs called ACE acts on angiotensin I
relationship between angiotensin II and aldosterone?
angiotensin II stimulates aldosterone secretion
true or false ACTH has tight regulator function with regard to aldosterone
false - it’s a modest effect
effect of angiotensin II?
- increases Na absorption and K excretion
- water retention, higher blood pressure
what’s the speculated use of angiotensin II in the brain?
functions as a local regulator playing a role in thirst behavior
what cells recognize Na levels in the kidney tubule?
Macula densa
from angiotensin II, how is it degraded?
converted to angiotensin II by aminopeptidase and then converted to degradation products
when macula densa cells recognize lower sodium concentration, this does what pertaining to the release of renin?
upregulates
immediate effects of angiotensin II?
- acts directly on the blood vessels inducing vasoconstriction
slow angiotensin II effects?
affects sodium reabsorption
longer term angiotensin II effects?
regulation of wall tension
how does aldosterone function?
gene expression
sodium is reabsorbed, potassium is being pushed out, water follows it back in (slide 11)
what channels are on the luminal side?
- Sodium ENaC channels - these are the ones affected by aldosterone
- aquaporins (slide 10)
what channels are on the basal side?
Sodium K-ATPase - this one balances the effect of aldosterone onto the ENaC (slide 10)
where does aldosterone mainly work?
distal tubules & collecting ducts of the kidney
what happens when you have too much aldosterone?
Conn’s syndrome - increases blood pressure (excess sodium retention)
- serum alkalosis and neuropathy (excess K+ and H + excretion)
what causes Conn’s syndrome
either adrenal hyperplasia or tumors
where are natriuretic peptides secreted?
cardiac muscle
what do natriuretic peptides do?
control sodium release by kidney; reduce blood volume and pressure
what other hormone(s) can the adrenal cortex make?
sex steroids
what is adrenarche?
earlier than usual maturation of adrenal glands as a result of sex steroid syntehsis
expand CAH
congenital adrenal hyperplasia
what is CAH?
- excessive androgen production
- masculinization of genitalia
go look at slide 16
:)
what happens with a CAH female
- ovary forms because of absence of Y chromosome
- large adrenal glands produces sex hormones that can lead to DHT which can lead to the masculinization of external genitalia
what happens when you have a deficiency in 21 hydroxylase enzyme?
- low cortisol (less negative effect on pituitary, less ACTH produced)
- low aldosterone
- more tropic signals coming to the adrenal gland
how is CAH treated?
surgery at birth
which nervous system is the adrenal medulla involved in?
sympathetic
what response does the adrenal medulla elicit?
fight/flight; increases blood pressure and cardiac output, dilate pupils
what catecholamines are produced in the adrenal medulla?
- norepinephrine
- epinephrine
what pathways inactivate norepinephrine and epinephrine?
Comt and Mao
what are met-enkephalin and leu-enkephalin?
related to endorphins; associated with runner’s high
acute fight/flight response?
integrates lots of organ systems to efficiently provide response
what organ systems get “neglected” during the fight or flight response?
skin, GI
function of epinephrine/norepinephrine?
- increase muscle glycogenolysis
- increase glucose levels in the brain
- reduces insulin concentration, which reduces uptake by other cells except the brain
- increases cardiac output
- increases blood pressure/blood flow
what kind of receptors are the adrenergic receptors?
GPCRs
what is salbutamol?
B2 inhibitor; used to treat asthmatic symptoms
difference between epinephrine and norepinephrine?
epi - more robust in terms of cardiac stimulation and metabolic effects
nor - more robust in blood vessel constriction
true or false: anything that affects the adrenal cortex can also affect the adrenal medulla
yeah, because cortisol has an effect on catecholamines as well
what happens when you have hyper-secretions of catecholamines?
- caused by tumors causes general symptoms - headache - hypertension - sweating - palpitations - chest pain - anxiety - glucose intolerance - increased metabolic rate (similar effects to anxiety)
