neural control of blood pressure Flashcards
what issues can hypotension lead to and why?
chronic fatigue and inability to exercise
not enough blood and oxygen reaching organs
what issues can hypertension lead to and why?
aneurysms due to overstretched arteries
what is an aneurysm?
when an overstretched artery wall is weaker than normal and can burst suddenly
why is hypertension especially dangerous in atheromatous arteries?
high pressure causes plaque to rupture
turns into a thrombus which might block an artery
or might become an embolus and block smaller downstream arteries
what systems regulate blood pressure and which is faster?
neural - faster
hormonal
what type of feedback is neural control of blood pressure?
negative feedback
where are sensors for blood pressure found?
aortic sinus above the aortic valve
carotid sinus in the internal carotid
which nerves take impulses from the carotid sinus to the brain?
vagus
glossopharyngeal
where are the cell bodies of the carotid sinus afferents?
jugular and nodose ganglia
where do the afferents in the glossopharyngeal nerve come from?
tongue, pharynx, larynx and carotid sinus
where do the sensory afferents in the vagus nerve come from?
lungs, gut, pharynx, larynx and carotid sinus
what is stretch in the carotid sinus proportional to?
blood pressure
what does the stretch on the carotid sinus cause?
constant stream of action potentials
where do the nerves from the carotid sinus feed into?
nucleus of the solitary tract
what is the nucleus of the solitary tract and where is it found?
integrating centre for sensory nerve fibres from organs
medulla oblongata
what does the NTS give input into?
the main vasomotor centre in the medulla
the nucleus ambiguus
what is normal blood pressure defined as?
120/80
explain the series of events that happen when blood pressure is too low
rate of firing APs from the baroreceptors decreases detected by the NTS NTS signals to VC VC sympathetic output increases arterioles constrict total peripheral resistance increases
give an equation for mean arterial pressure
cardiac output x total peripheral resistance = mean arterial pressure
explain the series of events that occur when blood pressure is too high
bp too high = baroreceptor too high = VC inhibited –> reduced sympathetic outflow –> arterioles relax –> TPR reduced
where do axons from the vasomotor centre go?
down the spinal cord in the lateral reticulospinal tract to the sympathetic pre-ganglionic neurons in the intermediate part of the lumbar and thoracic ventral horn
what does the cardio inhibitory centre do and how?
increases parasympathetic vagal output to the heart
vagus acts on the SAN and slows it down
reduces CO
reduces BP
at what BP does someone have hypertension?
140/90
at what BP does someone have hypotension?
90/60
