control of blood pressure: role of the vasculature Flashcards
what is the neural control of short term control of blood pressure
mediated by the baroreceptor reflex
negative feed-back loop of
- stretch-sensitive baroreceptors acting as the sensors (afferents)
- cardiovascular control centre in the medulla oblongata acting as the integrator
- autonomic neurons acting as the effectors (efferents)
how is pulse pressure calculated
Pulse pressure = systolic BP - diastolic BP
how is mean arterial BP calculated
MAP = diastolic BP + 1/3(pulse pressure)
what is pulse pressure
the difference between systolic an diastolic BP
determined by the volume of blood ejected and the compliance of the arterial vasculature
an increase in volume of blood ejected by the ventricles during exercise, with relative compliance of vessels will cause an increase in pulse pressure
what factors affect systolic BP
stroke volume
compliance
what is the effect of stroke volume on systolic BP
SV = volume of blood ejected from the left ventricle (ml)
larger SV = larger pulse pressure at any given compliance
what is the effect of compliance on systolic BP
aortic/arterial distensibility (afterload)
aorta is the most compliant vessel
low compliance = greater cardiac workload (an inverse relationship)
what factors affect diastolic BP
arteriolar resistance
heart rate
what is the effect of arteriolar resistance on diastolic BP
arteriolar resistance = total peripheral resistance
modified by disease (atherosclerosis) and physiology (vasoconstriction)
what is the effect of heart rate on diastolic BP
heart rate = cardiac cycles per unit time (bpm)
increase in heart rate increases diastolic BP
how is arterial blood pressure calculated
arterial Bp = cardiac output x total peripheral resistance
what is arterial blood pressure
drives flow
is pulsatile
is a regulated variable
how does the heart increase blood pressure
increased sympathetic drive
increased noradrenaline release from postsynaptic neurons
binds to β1 adrenoceptors on the myocardium
increased chronotropy
increased dromotropy
increased inotorpy
decreased lusitropy
increased cardiac output
increased arterial BP
how does the vasculature increase blood pressure
increased sympathetic drive
increased noradrenaline release from postsynaptic neurons
binds to ⍺1 adrenoceptors on the myocardium
increased vasoconstriction
increased total peripheral resistance
increased arterial BP
how does the heart decrease blood pressure
increased parasympathetic drive
increased acetylcholine release from postsynaptic neurons
binds to muscarinic M2 receptors on the myocardium
decresed chronotropy
decreased dromotropy
decreased inotorpy
increased lusitropy
decreased cardiac output
decreased arterial BP
how does the vasculature decrease blood pressure
increased parasympathetic drive
increased acetylcholine release from postsynaptic neurons
binds to muscarinic M3 receptors on the myocardium
increased vasodilation by endothelium dependent mechanism
decreased total peripheral resistance
decreased arterial BP
what is chronotropy
heart rate
what is dromotropy
speed of conduction
what is inotropy
force of contraction
what is lusitropy
rate of relaxation
what is anaphylaxis
a hypersensitive reaction involving mast cell degranulation which then causes release of vasoactive compounds which cause circulatory collapse due to severe hypotension
how is anaphylaxis treated
the acute management of anaphylaxis involves administration of adrenaline to induce vasoconstriction to restore blood pressure
what is therapeutic vasoconstriction
the vasculature expresses β2 adrenoceptor which in physiological conditions respond to circulating adrenaline and induce vasoilation BUT in those same physiological conditions the effects of noradrenaline on the ⍺1 adrenoceptor predominates and vasoconstriction predominates
