Control of blood pressure Flashcards
what three factors in the maintenance of arterial blood pressure
- blood volume
- peripheral (systemic) vascular resistance (PVR or SVR, vaso constriction/dialation)
- cardiac output (hr.sv)
how does the neural control center control bp
CV conrtol in the medulla-> SNS impulses release norepi/epi-> then either:
- excited alpha receptors in vessels-> vasoconstriction
- excites beta receptors in heart-> increase hr-> increased force of cardiac contraction
what are the two baroreceptors
- arterial pressoreceptors
2. arterial receptors (volume receptors)
how do arterial pressoreceptors work
- sense changes in the “pressure” in the major arteries ia stretch
- send impulses to SV conrol center to either increase or decrease SNS inhabition
where are arterial pressoreceptors located
in aorta and carotid arteries
how do arterial receptors work
sense changes in volume in large VEINS
where are arterial receptors locatd
in vena cava and right atrium
what is the chain for atrial receptors
decreased bp-> decrease blood flow through major arteries and venous return sensed by receptors-> sv control center-> DECREASES inhibition-> increased SNS response-> increased HR and force of contraction, vasoconstriction-> increased Bp
how is angiotensin II made
decreased blood volume/flow to kidney-> stimulates kidney to release renin-> liver makes angiotensinogen-> renin and angiotensinogen combine to make angiotensin I-> ace in the lungs converts angiotensin I into angiotensin II
what does angiotensin II do with kidneys
stimulates the adrenal cortex to increase the release of aldosterone which causes the kidneys to increase sodium reabsorption which increases blood volume and restores bp and volume
what does angiotensin II do with the vessels
is a direct vasoconstrictor and acts on the receptors in the BV’s which increase BP
what does angiotensin II do with the brain
acts on posterior pituitart and stimulates thirst, increased ADH to increase H2O resorption in the kidneys which raise blood volume and restores BP
What are the two types of hypertension
primary
secondary
what is primary hypertension
90%- no known cause- treatable
what is secondary hypertension
10%- due to a known cause- fixed depending on cause
what is the hypothesis of primary HTN
- increase in BV
- overstimulation of SNS
- H2O + Na retention by kidneys (chronic)
why does renovascular disease cause secondary HTN
renal stenosis or clot which stimulates the R/A system because kidneys don’t believe that the whole body is getting blood when it is actually just the kidney cuz of the clot
what are the 3 patho of HTN
- vascular cellular proliferation and damages arterial walls
- thickening of basement mems and arteries
- permanent narrowing and poor perfusion out of caps
what are the clinical mani of mild to moderate HTN
may be asymptomatic or vague
what are the symptoms with ADVANCED HTN
r/t increased pressure in arterial system and fragile caps:
- headache, epistaxis (nosebleed)
- dizziness, unsteadiness, blurred vision
- retinopathy- retina damage
- CAD
- renal insufficiency
what organs are most acutely affected by HTN
heart, brain, eyes, kidneys
what are the matinence of HTN
drug therapy
exercise
diet
low Na+
what is orthostatic hypotension
decrease in bp upon standing due to poor reflex vasoconstriction with dizziness, blurred vision, fainting
what is shock
overall or generalized reduction of adequate blood flow and o2 delivery to the tissues
