reg of bp Flashcards
(39 cards)
what are the equations for MAP?
1- MAP = CO X TPR
2- diastole + 1/3 pulse pressure
3- 2/3 diastole + 1/3 systolic
whats the main short term regulation for map?
baroceptor reflex
whats the longterm regulation of map?
RAAS system
what constitutes a reflex? and whats the role of each?
1- An integrating center –> sets a point for normal desired level of something
2- receptor —> sense the variable and detecting changes
3- An afferent pathway – > take the info to the center
4- an efferent pathway –> take orders from the center to the effector
5- effector –> muscle , endocrine cell ,etc which is responsible for the variable
whats the set point of baroreceptor for MAP?
100 mmHg
where is the location of baroreceptor?
1- aortic arch
2- carotid sinus
whats afferent nerve of each?
aortic arch –> vagus nerve
carotid sinus –> glossopharyngeal nerve
what does the baroreceptor do?
when theres a drop in pressure it will :-
Sympathetic activation –> increase HR (chronotropic ) increase contractility via norepinephrine ( inotropic ) , increase the resistance and then it will increase the pressure
inhibit parasympathetic activation
When theres an increase the opposite happens?
how does the brain know from the barorecptor if the Pressure is high or Low
by the frequency of action potentials from baroreceptors :-
the carotid/aorta is stretched –> high bp –> baroreceptor increase frequency of Ap leading to increased para and reduced para
low –> opposite
what are the effects of sympathetics activity of baroreceptor?
1- Increased firing rate of sa node positive chronotropic
2- Increased contractility positive inotropic
3- vasoconstriction of artieroles increasing resistance
4- vasoconstriction of veins –> increase preload
para is opposite to all of this
whats valsalva maneuver ?
a technique used to check if baroreceptor are working,
close your nose and blow –> increased intrathoracic pressure –> decreased preload –> less MAP cuz less SV –> increased heart rate by baroreceptor
why is baroreceptor not working in chronic hypertension?
1- increased the set point in the integrating system its no longer 100
2- decreased sensitivity of the receptor itself due to the prolonged hypertension
whats the long term regulation of bp?
RAAS system
which kidney cells produce renin?
juxtaglomerular cells
what are the reasons that could lead to renin release?
1- increased sympathetic tone
2- decreased renal perfusion pressure ( renal baroreceptor )
3- Decreased NACL in distal tubule
what are chemoreceprots and what two types we have?
chemoreceptors they sense change in chemicals composition
we have 2 types :-
1- peripheral chemoreceptor
2- central chemoreceptors
wheres peripheral chemoreceptor found?
carotid bodies and aortic bodies like baroreceptors
wheres central chemoreceptor found?
medulla of brain
what could activate the peripheral chemoreceptors?
1- Decrease arterial PO2
2- Increase PCO2 and decrease PH ( acidic )
what are the effects of peripheral chemoreceptors?
increased sympathetic outflow in skeletal muscle and renal and splanchnic vascular beds ——-> arteriole vasoconstriction
increased PARASYMPHETIC –> IN HEART to decrease heart rate
increase ventilation –> increase heart rate ( lung inflation reflex )
what could activate of the central chemoreceptor?
1- change in aterial pco2 and ph ( brain ischemia )
2- less sensitive O2 changes
what are the effects of central chemoreceptor?
increase the sympathetic outflow –> arteriole constriction at the brain to redirect the flow ( cusshing reflex) however increase peripheral resistance –> increase arterial pressure
whats cushing reflex?
its a reflex that done to save brain from ischemia
what could activate the cushing reflex?
increased intracranial pressure ( brain tumor ) –> compression of arteries –> decreased blood perfusion
Increased PCO2 and DECREASED PH
