Regulation of Arterial Blood Pressure Flashcards
(23 cards)
Response to head up tilt normally and in autonomic neuropathy
HR increase
HR stays the same
5 elements of baroreflex
Sensor to detect BP
Affarent from sensor to controller
Controller/integrater that compares current with desired
Efferent that carries to effectors
Effectors
Sensors of baroreflex
Stretch receptors in the carotid sinus and arch of aorta
Inc BP—inc stretch—–inc activation of these receptors
Loop with SNA
Inc AP…inc barorecptor….dec sympathetic….dec arteriolar smooth muscle contraction….dec resistance…dec BP
Majority of baroreflex depends on
SNA - NE, Beta 1
Important exception is PS control of HR
PS control
BP increases….inc PS nerve activity which dec HR via Ach/muscarinc
Plasma volume effect
Due to atrial stretch receptors in the RA
If you eleiminate baroreflex
Sinoaortic denervation
BP fluctuates widely but overall average is about the same
Barorelfex summary
Minimizers moment to moment fluctuations in BP
Other mechs responsbile for LT BP regulation
Overview of neural control
Vagus acts on heart from BS
Sympathetic nerves from IML…sensory from heart back to IML
Chainganglion also to vasomotor fibers
Fagus nerves to lungs
BS anatomy of baroreflex
NTS - receives info from caerotid sinus and aortic arch
Nuc ambiguous - vagal efferent to the AV node
RVLM to symp chain to myocardium for sympathetic
Full tract of baroreflex in terms of inc BP
Sensory to NTS —–to N amb—-activates vagal stimulation
Sensory to CVLM…inhibits RVLM…RVLM normally activates sympathetic
Sequence in ogoing from supine to UR
Gravity bloods
Starves heart
Dec CO…dec BP…dec cerebral flow
Dec carotid sinus pressure activates baroreflex
Inc SNA, dec PNA,—–tachycardia, inc SV
Renovascular
Neurogenic
Salt sensitive
Renal artery occlusion to RAAS
Inc SNA means inc CO and TPR
High salt load means inc BV
Arterial pathologies
Obesity related
Endothelial dysfunction
Essential
Artrial compliance
????
Impaired release of NO
???
Why does baroreflex dec in older age
Dec in compliacne of the arteires in which baroreceptors reside
Mutliple causes of HTN
INteractive efrects of dietary sodium and behavioral stress
Humans learn to elevate arterial BP to minimize perception of pain
Pmc
This is where the arteiral pressure and CVP meet
Mean circulatory filling pressure
Vascular function equation
VR = (resistance)(Pmc-Pra)
Vascular function curve with vasoconstrction
Increase the Pmc and moves the curve to the right
Starlings curve and vascular ufnction curve plotted on same graph
Find the intersetion and this is steady state operating point
Effects on vascular fxn/starling curve
Inc in SNA shifts the starling curve up
Inc in contractility shifts the vascular function curve to the right
This means heart can perform more work without an increase in preload
Positive inotropism on PV loop
Dec in ESV and therefore dec in LV diastolic pressure
Inc in SV automatircally fosters increase in pressure graident for venous return
