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Flashcards in neural control of blood pressure Deck (29)
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1
Q

what issues can hypotension lead to and why?

A

chronic fatigue and inability to exercise

not enough blood and oxygen reaching organs

2
Q

what issues can hypertension lead to and why?

A

aneurysms due to overstretched arteries

3
Q

what is an aneurysm?

A

when an overstretched artery wall is weaker than normal and can burst suddenly

4
Q

why is hypertension especially dangerous in atheromatous arteries?

A

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

5
Q

what systems regulate blood pressure and which is faster?

A

neural - faster

hormonal

6
Q

what type of feedback is neural control of blood pressure?

A

negative feedback

7
Q

where are sensors for blood pressure found?

A

aortic sinus above the aortic valve

carotid sinus in the internal carotid

8
Q

which nerves take impulses from the carotid sinus to the brain?

A

vagus

glossopharyngeal

9
Q

where are the cell bodies of the carotid sinus afferents?

A

jugular and nodose ganglia

10
Q

where do the afferents in the glossopharyngeal nerve come from?

A

tongue, pharynx, larynx and carotid sinus

11
Q

where do the sensory afferents in the vagus nerve come from?

A

lungs, gut, pharynx, larynx and carotid sinus

12
Q

what is stretch in the carotid sinus proportional to?

A

blood pressure

13
Q

what does the stretch on the carotid sinus cause?

A

constant stream of action potentials

14
Q

where do the nerves from the carotid sinus feed into?

A

nucleus of the solitary tract

15
Q

what is the nucleus of the solitary tract and where is it found?

A

integrating centre for sensory nerve fibres from organs

medulla oblongata

16
Q

what does the NTS give input into?

A

the main vasomotor centre in the medulla

the nucleus ambiguus

17
Q

what is normal blood pressure defined as?

A

120/80

18
Q

explain the series of events that happen when blood pressure is too low

A
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
19
Q

give an equation for mean arterial pressure

A

cardiac output x total peripheral resistance = mean arterial pressure

20
Q

explain the series of events that occur when blood pressure is too high

A

bp too high = baroreceptor too high = VC inhibited –> reduced sympathetic outflow –> arterioles relax –> TPR reduced

21
Q

where do axons from the vasomotor centre go?

A

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

22
Q

what does the cardio inhibitory centre do and how?

A

increases parasympathetic vagal output to the heart

vagus acts on the SAN and slows it down
reduces CO
reduces BP

23
Q

at what BP does someone have hypertension?

A

140/90

24
Q

at what BP does someone have hypotension?

A

90/60

25
Q

when is hypotension significant?

A

when symptoms are present e.g. dizziness/fainting

26
Q

what causes hypertension?

A

chronic narrowing/constriction of arteries

27
Q

what are the causes of chronic narrowing/constriction of arteries?

A

increased tonic vasoconstriction via sympathetic NS
arteriole endothelium damaged –> constriction
malfunction of the hormonal control system

28
Q

why do people with hypertension have a higher BP set point?

A

less sensitive stretch receptors
normal BP detected as too low
system corrects this by increasing sympathetic output
raises BP

29
Q

why are stretch receptors less sensitive in hypertension?

A

atheroma formation in the carotid sinus
makes walls stiffer
more pressure needed to distend them
normal BP detected as too low