cardiovascular sensory regulation & control Flashcards
how is blood pressure and blood flow controlled
through interconnected neg feedback systems that work by adjusting HR, SV, systemic vascular resistance and blood volume
do all feedback systems act at the same speed
no some act faster or slower
some are also shorter or longer than others
where is the cardiovascular centre found
in the medulla oblongata
what does the cardiovascular centre do
regulate HR and SV
controls neural, hormonal and local neg feedback systems that regulate blood pressure and blood flow to specific tissues
what do groups of neurones in the CV centre do
regulate HR, contractility of ventricles and blood vessel diameter
where are cardio-stimulatory and cardio-inhibitory centres found
in the CV centre
what does vasomotor centre do
control blood vessel diameter
receives input from both higher brain region and sensory receptors
3 main types of sensory receptors
proprioceptors
baroreceptors
chemoreceptors
what do proprioceptors do
monitor movements of joints and muscles to provide input during physical activity
what do baroreceptors do
monitor pressure changes and stretch in blood vessel walls
what do chemoreceptors do
monitor concentration of various chemicals in the blood
what does the output from CV travel along
neurons of ANS
what does the sympathetic (stimulatory) system oppose
the parasympathetic system (inhibitory)
where are baroreceptors found
found internal carotid arteries and other large arteries in neck and chest
what does the carotid sinus reflex do
helps regulate blood pressure in brain
what does the aortic reflex do
regulate systemic blood pressure
what happens in baroreceptor reflexes when BP falls
baroreceptors stretched less which leads to slower rate of impulses to CV centre
what does CV centre do once receiving signals from baroreceptor
decrease parasympathetic stimulation and increases sympathetic stimulation
where are chemoreceptors found
close to baroreceptors of carotid sinus and aortic arch
what do chemoreceptors do
detect
- hypoxia (low O2)
- hypercapnia (high CO2)
- acidosis (high H+)
and send signals to CV
what does cv centre do after receiving signals from chemoreceptors
it increases sympathetic stimulation to arterioles and veins
produces vasoconstriction and an increase in BP
what does martial natriutertic peptide (ANP) promote
natriuresis (loss of sodium)
what does the atrial myocytes do
synthesise, store and release ANP in response to stretch
what is the effect of natriuresis
renal vasodilation
increased blood flow= increased GFR
means more Na+ reaches macula densa meaning more Na+ secreted
what can ANP inhibit
actions of renin and generally opposes effects of angiotensin II
how does systemic control of arteriolar diameter occur
by sympathetic innervation
what does tonic release or norepinephrine do
(systemic control of AD)
binds of a-adrenergic receptors on vascular smooth muscle
helps maintain tone of arterioles
what happens when sympathetic release of norepinephrine decreases
the arterioles dilate and vice versa
how does local control of AD work
by paracrine factors
- vascular endothelium
- low O2 and high CO2
- active hyperaemia
- reactive hyperaemia
what is the vascular endothelium sensitive to
pressure and flow
what is the vascular endothelium the major determinant of
vascular resistance
stages of active hyperaemia
- increase of tissue metabolism
- increase in release of metabolic
vasodilators into EFC - arterioles dilate
- decreased resistances creates increased blood flow
- O2 and nutrient supply to tissue increases as long as metabolism is increased
reactive hyperaemia stages
- decreased tissue blood flow due to occlusion
- metabolic vasodilators accumulate in EFC
- arterioles dilate, but occlusion prevents blood flow
- remove occulusion
- decreased resistances creates increased blood flow
- as vasodilators wash away, arterioles constrict and blood flow returns to normal
