baroreceptors Flashcards
what is blood
a complex fluid that carries oxygen and carbon dioxide, and is important in clotting
what influences blood flow
blood flow in the vasculature is linearly proportional to the pressure difference between two points, along a pressure gradient
flow = Δpressure/ resistance
what is blood pressure
the pressure blood exerts on the walls of blood vessels
pressure differences along the vascular tree drives blood flow in the cardiovascular system
because one is dependent on the other, a fall in arterial blood pressure can sufficiently reduce flow that it proves fatal
what is arterial blood pressure
arterial BP = cardiac output x total peripheral resistance
drives flow
is pulsatile
is a regulated variable
how is blood pressure controlled
- short-term
- long-term
what is short term BP control (basic)
baroreceptor reflex
neural control
seconds to minutes
what is long term BP control (basic)
renin-angiotensin aldosterone system
hormonal control
relies on control of blood volume
control of cardiac output
involves kidneys
what is neural control of BP
mediated by the baroreceptor reflex
negative feedback loop of:
- stretch-sensitive baroreceptors acting as the sensors (afferents)
- cardiovascular control centre in the medualla oblongata acting as the integrator
- autonomic neurons acting as the effectors (efferents)
how is arterial blood pressure monitored
by peripheral sensors
arterial baroreceptors
cardiopulmonary baroreceptros
what are arterial baroreceptors
afferent nerve fibres which relay information to the brain about blood pressure
are ‘ideally’ located stretch receptors
located in the carotid sinus and aortic arch
what are cardiopulmonary baroreceptors
afferent fibres of 4 types
located in ‘low pressure regions’, the heart an dpulmonary artery
what are the 4 types of cardiopulmonary baroreceptors
- myelinated veno-arterial mechanoreceptors
- non-myelinated mechanoreceptors
- coronary artery baroreceptors
- chemosensors
what is the relationship between mean arterial blood pressure and carotid sinus firing frequency
an increase in mean arterial blood pressure causes an increase in carotid sinus firing frequency
what is the process of baroreceptor activation
increase in blood pressure
activates stretch receptors in the carotid sinus
impulses are transmitted to glossopharyngeal nerve
impulses transmitted to nuclei tractus solitarii
stimulation of nuclei tractus solitarii
inhibition of sympathetic nervous system
reduction in smooth muscle contraction
vasodilation
fall in blood pressure
- a cyclical process which is always active
what is short term control of BP
not all baroreceptors are created equal
carotid sinus baroreceptors are more sensitive - they cause greater changes in blood pressure than aortic arch baroreceptors
both the carotid sinus and aortic arch contain fibres which help deal with normal and high level blood pressure changes
what are A-fibres
deal with normal range blood pressure changes
what are C-fibres
deal with high level blood pressure changes
what is short term control of BP summary
baroreceptor reflexes
seconds to minutes
what is long term control of BP summary
control differs
relies on control of blood volume
control of cardiac output
involves kidneys
summary of baroreceptors
blood pressure is a regulated variable because it is integral to maintaining blood flow in the vasculature
the detection of short term changes in blood pressure is facilitated by the baroreceptors - arterial and cardiopulmonary
