APK 2105C Lecture Notes - Lecture 36: Carotid Sinus, Medulla Oblongata, Aortic Arch
16 Jun 2018
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Chapter 14, Lecture 7
Vessels & Blood Pressure
• MAP = CO x TPR
o Flow = pressure gradient / resistance
o Constant MAP = coming and going at the same rate
o Increased MAP = same resistance, more CO = more stretch in wall, more
pressure
▪ Any increase in SV or HR
o Increased MAP = more CO, more resistance = more stretch, more pressure
o To increase MAP, increase CO or TPR
• MAP = HR x SV x TPR
• Regulation of MAP
o Only through extrinsic mechanisms
o Short term vs. long term regulation
▪ Long term = blood volume regulation = minutes/hours/days
▪ Short term = seconds/minutes
o Neural and hormonal changes
▪ What is more associated with short vs. long term regulation?
• Nervous = immediate responses
• Hormonal = longer term
▪ Neural control of MAP = arterial baroreceptors
• Location
o Aortic arch
o Carotid artery bifurcation = carotid sinus (neck)
• Detect changes in pressure in the wall
• Stretch receptors—signaled when vessel wall stretches with more
blood volume
• Always feeding information to CNS
o Increased pressure = increased AP frequency
o Decreased pressure = decreased AP frequency
o Change in pressure = change in signal to CNS—have a
baseline AP frequency when things are normal
• Major neural pathways in CV
control
o Medulla oblongata
▪ CV control center
• Used to
decide how
to control
CV
• Sent out
using
autonomic
control—
heart or
blood
vessels
▪ Parasympathetic innervations
• Innervates SA and AV nodes
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Document Summary
Vessels & blood pressure: flow = pressure gradient / resistance, constant map = coming and going at the same rate. Increased map = same resistance, more co = more stretch in wall, more pressure: any increase in sv or hr. Cv: sent out using autonomic control heart or blood vessels, parasympathetic innervations. Innervates sa and av nodes: baroreceptor reflex. Increase in hr and sv will increase co. Increased sympathetic tone: where is it released from, adrenal medulla, secreted in increased sympathetic tone, what receptors does it bind to, variable effect in vasculature, vasodilation in skeletal/cardiac muscle, vasoconstriction to all other organs, overall effect. Increase map: neg feed back, angiotensin ii, plasma protein derived from angiotensinogen, angiotensinogen +renin angiotensin i + ace angiotensin ii, long term basis, affects the kidneys more, adh secretion. Increase plasma volume increase pressure: vasopressor, neg feedback, vasopressin (adh) Immediate impact on vessels: long term impact to increase blood volume.
