Regulation of Arterial Pressure Flashcards
Where is the vasoconstrictor area located?
bilateral in the upper medulla
Where is the vasodilator area located?
lower medulla
What is the functional mechanism of the vasodilator area of the VMC?
inhibits the vasoconstrictor area
Where is the sensory area of the VMC located?
tractus solitaries
What structures influence the VMC?
1) Reticular substance
pons, di/mesencephalon
2) Hypothalamus
postlateral = excitatory
anterior = inhibitory
3) CortexHow does the sensory area of the VMC work?
innervated by vagus & glossopharyngeal reflexes, output to ANS.
When does the ischemic response occur?
when BP < 60 mmHg
What drives the ischemic resopnse?
metabolic/O2 lack in VMC
where are baro-receptors located?
aorta & carotid arteries
Describe the afferent pathway of the baroreflex?
vagal –> herrings –> glossopharyngeal
what is the effector pathway for the baroreflex?
SNS to heart/vasculature
What is the integrating center for the baroreflex?
VMC
When does acute control of BP take place?
1) baroreflex
2) heavy exercise ==> 30% increase in MAP
Describe the infinite feedback gain principle.
Indefinite increase in MAP –> indefinite increase in renal output
When is kidney output 0?
below 60 mmHg
What causes a long-term increase in BP?
1) Right-shift in RFC (decreased renal function)
2) Persistent change in salt/water intake
What are the effects of AngII?
1) vasoconstriction
2) increased ADH
3) increased aldosterone
4) increased thirst
5) increased SNS activity
What is the response to increased salt intake?
when ECT > 300 mOsm/L…
1) increased thirst
2) increased ADH
Where is renin secreted?
JG cells of kidney
When is renin secreted?
1) primary: response to decreased MAP, decreased V
2) also, decreased Na
3) also, beta-adrenergic activation
How is AngII activated in the Renin-Angiotensin system?
1) renin secreted (peptidase)
2) angiotensinogen –> Ang1
- - Ang1 found in many tissues!
3) ACE: Ang1 - Ang2
