Baroreceptors Flashcards
Calculation of Flow
Flow = ^ Pressure / Resistance
Calculation fo Arterial Blood Pressure
Arterial Blood Pressure = Cardiac Output x Total Peripheral resistance
Feedback Loop baroreceptor reflex
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)
What are A fibres
A fibres deal with normal range blood pressure changes
what are C fibres
C fibres deal with high level blood pressure changes
Not all baroreceptors are created equal
carotid sinus baroreceptors are more sensitive that cause greater changes in blood pressure that aortic arch baroreceptors
Long term control differs
Longer term control differs : relies on control of blood volume think control of cardiac output by starling’s law of the heart and involves kidneys
calculation of pulse pressure
Pulse Pressure = systolic blood pressure - diastolic blood pressure
mean arterial blood pressure
mean arterial blood pressure = DBP + 1/3 (Pulse Pressure)
what is pulse pressure determined
Determined by the volume of blood ejected and the compliance of the arterial vasculature
what causes an increase in pulse pressure
increase in volume of blood ejected by ventricles during exercise with relative compliance of vessels will cause an increase in pulse pressure
what is stroke volume
Stroke volume - is volume of blood ejected
what is compliance
compliance is arterial distensibility
reltaionship between low complaince and workload
low compliance means greater cardiac workload
How effectors alter heart increasing blood pressure
increased sympathetic drive
Increased noradrenaline release from post synaptic neurons
Binds to β1 adrenoreceptors expressed on the myocardium Increased chronotropy, dromotropy, inotropy and decreased lusitropy
Results increased cardiac output(CO)
how effectors alter vascualture increasing blood pressure
Increased sympathetic drive
Increased noradrenaline release from post synaptic neurons
Binds to α1 adrenoreceptors expressed on the vasculature Increased vasoconstriction
Results in increased total peripheral resistance(TPR)
how effectors alter the heart decreasing blood pressure
Increased parasympathetic drive
Increased acetylcholine (Ach) release from post synaptic neurons
Binds to muscarinic M2 receptorsexpressed on the myocardium Decreasedchronotropy, dromotropy, inotropy and increased lusitropy
Results in decreased cardiac output (CO)
how effectors alter the vasculature decreasing blood pressure
Increased parasympathetic drive
Increased acetylcholine (Ach)release from post synapticneurons
Binds to muscarinic M3 receptors expressed on the vasculature
Increased vasodilation by endothelium dependentmechanismResults indecreasedtotal peripheral resistance(TPR)
Anaphylaxis
Anaphylaxis is a hypersensitivity reaction involving mast cell degranulationwhich then causes release of vasoactive compounds, which amongst otherthings cause circulatory collapse due to severe hypotension
plasma volume is altered by
Plasma volume is altered by salt exretion by RAAS , antidiuretic hormone and atrial natiruretic peptide
RAAS
Decreased renal perfusion pressure aka a decrease in effective circulating volume→ Rise in sympathetic nervous system activity to kidneys→ Decreased NaCl concentration in the macula densa
Anigotensin II stimualtes
Angiotensin II stimulates aldosterone , vasoconstriction and thirst
