5.2 Heart Rate Flashcards
what is normal heart rate
70 beats per minute
is heart rate voluntary or involuntary?
involuntary
what nervous system controls heart rate?
autonomic
which area of the brain is responsible for controlling heart rate?
medulla oblongata
what are the 2 centres of the medulla oblongata?
cardiac excitatory
cardiac inhibitory
what does the cardiac excitatory centre do?
increases heart rate by sending impulses through sympathetic nerve to SAN
what does the cardiac inhibitory centre do?
decreases heart rate by sending impulses through parasympathetic nerve to SAN
which centre is stimulated is depends upon what?
information from receptors
what are baroreceptors? what do they detect?
pressure receptors detecting changes in blood pressure
where are baroreceptors found?
aorta
vena cava
cartoid arteries
what are chemoreceptors? what do they detect?
chemical receptors
detect changes in levels of chemicals within the blood
where are chemoreceptors found?
cartoid artery (supplies brain with blood)
what are chemoreceptors sensitive to changes in?
blood pH
if CO2 levels in the blood increase what happens to blood pH?
it decreases
why does blood pH decrease if CO2 levels increase?
CO2 interacts with H2O in the blood forming carbonic acid
when blood pH decreases chemoreceptors send an impulse to where?
medulla oblongata
(decrease in pH) response is coordinated in which centre? resulting in an impulse being sent where?
cardiac excitatory centre
along sympathetic nerve
(decrease in pH) from sympathetic nerve the impulse reaches the SAN causing what?
increase in heart rate
(decrease in pH) increase heart rate moves CO2 where?
away to the lungs in order to get rid of it
(decrease in pH) as the CO2 is exhaled from the lungs what happens to pH?
returns to normal
(decrease in pH) as pH returns to normal what happens?
change detected by chemoreceptors sends an impulse to medulla oblongata then to cardiac inhibitory centre sends an impulse down parasympathetic as no more increase needed.
increase in blood pressure is detected by what?
baroreceptors
(increase in bp) baroreceptors send messages to the…..
medulla oblongata
(increase in bp) the medulla oblongata sends an impulse to where?
cardiac inhibitory centre
(increase in bp) the cardiac inhibitory centre coordinates a response along where? resulting in what?
parasympathetic nerve leading to SAN
decrease in heart rate until bp returns to normal
(increase in bp) when bp returns to normal what happens?
baroreceptor sends message to medulla oblongata then to cardiac excitatory centre as decrease is no longer needed
when might more CO2 be produced?
exercising
