14.6 Controlling heart rate Flashcards
what part of the nervous system controls the heart rate?
autonomic
(involuntary)
what part of the brain controls the heart rate?
medulla oblongata
what is the autonomic system split into?
sympathetic
parasympathetic
what is the sympathetic system?
impulses which lead to secretion of noradrenaline by the accelerator nerve
INCREASES HEART RATE
what is the parasympathetic system?
impulses which lead to secretion of acetylcholine through the vagus nerve
DECREASES HEART RATE
what receptors effect the heart rate?
baroreceptors
chemoreceptor
what does a baroreceptor measure?
changes in the blood pressure
what does a chemoreceptor measure?
changes in the CO2 conc
can be seen through pH
what happens to pH of blood when CO2 increases and why?
it decreases as more carbonic ACID is formed
what happens to pH of blood when CO2 decreases and why?
it increases as less carbonic acid is formed
what response occurs if the chemoreceptors detect a low pH?
an increased heart rate to expel more CO2
drop in pH detected by chemoreceptors
medulla oblongata increases the frequency of electrical impulses sent to the SAN via sympathetic
SAN conducts waves of excitation more frequently
heart rate increases which means blood flow increases —> more CO2 removed —> CO2 levels return to normal
what response occurs if the chemoreceptors detect a high pH?
a decreased heart rate to restore to normal levels
fall in pH detected by chemoreceptors
medulla oblongata decreases the frequency of electrical impulses sent to the SAN via parasympathetic
SAN conducts waves of excitation less frequently
heart rate decreases which means blood flow decreases —> less CO2 removed —-> CO2 levels return to normal
what happens when the blood pressure is too high?
baroreceptors detect high blood pressure
impulse sent to medulla to decrease the heart rate
medulla oblongata decreases the frequency of electrical impulses sent to the SAN via parasympathetic
SAN conducts waves of excitation less frequently
slower heart rate = lowers blood pressure to normal
what happens when the blood pressure is too low?
baroreceptors detect low blood pressure
impulse sent to medulla to increase the heart rate
medulla oblongata increases the frequency of electrical impulses sent to the SAN via sympathetic
SAN conducts waves of excitation more frequently
higher heart rate = increases blood pressure to normal
