Exam 1 Flashcards
What stimulates Angiotensin II secretion
Angiotensin I availability (which is dependent on Renin)
What are the direct effects of Angiotensin II
- *Systemic vasoconstriction (strongest constrictor)
- *increase Na+ reabsorption and H+ excretion in prox. tubules (acts on kidneys via its self and by activating aldosterone)
- *Increase aldosterone secretion (on adrenal gland)
- vasoconstriction –> decreases GFR
- Increase ADH secretion
What are the indirect effects of Angiotensin II
- increase water reabsorption (increase blood volume)
- increase in Na+ reabsorption
- increase BP
- increase thirst (via CNS)
- Metabolic alkalosis
What stimulates aldosterone secretion
- *angiotensin II
- *Hyperkalemia (high potassium)
- *decrease plasma [Na+]
- ACTH (weakest influence)
What are the direct effects of aldosterone
- increase Na+ reabsorption in distal tubules and therefore the passive reabsorption of water
- increase K+ secretion in distal tubules
- increase H+ secretion in distal tubules
What are the indirect effects of aldosterone
- Increase water reabsorption
- increase BP
- decrease serum K+
- Metabolic alkalosis
What stimulates ADH secretion
- increased serum osmolarity (ECF)
- decreased BP/volume
- Angiotensin II
- hypoglycemia
What are the direct effects of ADH
- *Systemic vasoconstriction
- *Insertion of aquaporin channels in distal tubules and collecting ducts leading to increased FREE WATER REABSORPTION
- increase ACTH secretion
What are the indirect effects of ADH
- decrease serum Na+, which decreases serum osmolarity
- increase BP
- decreases urine output
What hormones stimulate reabsorption of Na+ in the kidneys
Angiotensin II and aldosterone
How is water reabsorption stimulated in the kidneys
indirectly stimulated by Angiotensin II and aldosterone
and directly by ADH
how is potassium reabsorption stimulated in the kidneys
indirectly stimulated by Angiotensin II and aldosterone
When levels of coritsol are elevated, how does it behave
like aldosterone
What prevents reabsorption of K+ in the kidneys
aldosterone
What drives K+ from ECF to ICF
- insulin
- catacholamines (epiniphrine)
What are the major overall effects of Angiotensin II
- increase BP
- increase blood volume
What are the major overall effects of aldosterone
- increase BP
- increase blood volume
- decrease serum [K+]
What are the major overall effects of ADH
- increase BP
- increase blood volume
- decrease [Na+]***
What stimulates renin secretion
- decrease in BP (renal perfusion pressure)
- decrease in [NaCl] around macula densa
- increase efferent SNS activity
- *Independent of one another
What is the rate limiting step in the mechanism of activating angiotensin II
the release of renin
*this is very tightly controlled
What is the job of renin
to hydrolyze angiotensinogen into angiotensin I
What inhibits renin
- increase in BP
- lots of Angiotensin II (which ultimatly increases BP)
- ANP (atrial natriuretic peptide)
- *independent of one another
When [NaCl] is low around the macula densa what is happening?
- Renin release will be stimulated
- the [ECF] will decrease
How is Kenny’s SNS affecting his RAA axis?
Kennys hypovolemia and increased HR stimulates increase SNS activity, which increases renin release
How does angiotensin II vasoconstrict?
promotes increase in intracellular [Ca2+] through actions of phospholipase C and IP3
Angiotensin II effects on the CNS
- increases sympathetic NS outflow
- increase BP
- increase cardiac output - dipsogenic actions (stimulates thirst)
- Increase ADH release
- increase ACTH
What stimulates thirts
- increase in plasma osmolarity (ECF)
- decrease blood volume
- decrease blood pressure
- increase in angiotensin II
- dryness of mouth
Angiotensin II effects on the kidneys
- decreases GFR due to vasoconstriction
- promotes Na+ reabsorption in the prox. convoluted tubule
- inhibits renin secretion
What is another name for vasopressin
ADH
At max. plasma ADH what will happen to urine production?
Volume of urine produced will be very low (low urinary flow rate) but the osmolarity of the urine produced will be very high
**Therefore, ADH is directed at water not solute!
What is our estimated plasma volume?
~ 3 liters
How does ADH increase water reabsorption in the distal tubules and collecting ducts?
By binding to its receptor and activating aquaporins which allow water to be reabsorbed
Normal physiological pH
- 4 +/- 0.02
* Baby’s don’t have as much control over this as adults
bronsted lowry acid
Can donate a proton