neural control of blood pressure

Question 1

what issues can hypotension lead to and why?

Answer 1

chronic fatigue and inability to exercise

not enough blood and oxygen reaching organs

Question 2

what issues can hypertension lead to and why?

Answer 2

aneurysms due to overstretched arteries

Question 3

what is an aneurysm?

Answer 3

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

Question 4

why is hypertension especially dangerous in atheromatous arteries?

Answer 4

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

Question 5

what systems regulate blood pressure and which is faster?

Answer 5

neural - faster

hormonal

Question 6

what type of feedback is neural control of blood pressure?

Answer 6

negative feedback

Question 7

where are sensors for blood pressure found?

Answer 7

aortic sinus above the aortic valve

carotid sinus in the internal carotid

Question 8

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

Answer 8

vagus

glossopharyngeal

Question 9

where are the cell bodies of the carotid sinus afferents?

Answer 9

jugular and nodose ganglia

Question 10

where do the afferents in the glossopharyngeal nerve come from?

Answer 10

tongue, pharynx, larynx and carotid sinus

Question 11

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

Answer 11

lungs, gut, pharynx, larynx and carotid sinus

Question 12

what is stretch in the carotid sinus proportional to?

Answer 12

blood pressure

Question 13

what does the stretch on the carotid sinus cause?

Answer 13

constant stream of action potentials

Question 14

where do the nerves from the carotid sinus feed into?

Answer 14

nucleus of the solitary tract

Question 15

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

Answer 15

integrating centre for sensory nerve fibres from organs

medulla oblongata

Question 16

what does the NTS give input into?

Answer 16

the main vasomotor centre in the medulla

the nucleus ambiguus

Question 17

what is normal blood pressure defined as?

Answer 17

120/80

Question 18

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

Answer 18

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

Question 19

give an equation for mean arterial pressure

Answer 19

cardiac output x total peripheral resistance = mean arterial pressure

Question 20

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

Answer 20

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

Question 21

where do axons from the vasomotor centre go?

Answer 21

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

Question 22

what does the cardio inhibitory centre do and how?

Answer 22

increases parasympathetic vagal output to the heart

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

Question 23

at what BP does someone have hypertension?

Answer 23

140/90

Question 24

at what BP does someone have hypotension?

Answer 24

90/60

Question 25

when is hypotension significant?

Answer 25

when symptoms are present e.g. dizziness/fainting

Question 26

what causes hypertension?

Answer 26

chronic narrowing/constriction of arteries

Question 27

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

Answer 27

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

Question 28

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

Answer 28

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

Question 29

why are stretch receptors less sensitive in hypertension?

Answer 29

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