why is it essential that heart rate can be changed?
uncontrolled can cause highpressure which can cause damage to capillaries and organs
exercise - needs to be higher so you can get more oxygen
sleep - lower rate to not waste energy
what is an accelerator nerve?
a part of the sympathetic NS and delivers a higher than usual frequency of impulses to the sinoatrial node to increase the heart rate
what is a vagus nerve?
opposite to accelerator nerve, part of parasympathetic NS and works to decrease heart rate by delivering a lower than usual frequency of impulses to the sinoatrial node
what is a chemoreceptor?
detect chemical changes, e.g. oxygen concentration, carbondioxide levels, pH of blood
what is a baroreceptor?
detects changes in blood pressure
what is the carotid artery?
primaryvessels supplying blood to brain and face
where are chemoreceptors found?
aorta
carotid artery
medulla
what occurs when there is a lowered pH?
high CO2 concentration, carbonic acid is formed when CO2 interacts with water in the blood
chemoreceptors detect this and trigger increasedheart rate
blood flows quickly to lungs so CO2 can be exhaled
where are baroreceptors located?
aorta
vena cava
carotid arteries
what is the negative feedback system of blood pressure?
too high, impulses sent to medulla oblongata, decrease heart rate, impulses sent along parasympathetic NS to SAN to decrease rate, back to normal
too low, impulses sent to medulla oblongata, increases heart rate, impulses send along sympathetic NS to SAN which increases rate, increases back to normal
what is the role of hormones in control of the heart rate?
times of stress, adrenaline and noradrenaline released
hormones affect pacemaker region of heart, speeding up heart rate by increasing frequency of impulses produced by SAN
what are the effects of exercise on heart rate?
blood pressure increases to supply cells with more oxygen and glucose
baroreceptor in carotid arteries detects and communicates to medulla oblongata
increases frequency of impulses down Vagus nerve (parasympathetic nervous system) to SAN
heart rate decreases
blood pressure returns to normal - so arteries don't sustain any unnecessary damage
what are effects of more CO2 in blood?
pH decreases as more CO2 released by aerobic respiration from cells, dissolves in blood forming carbonicacid
chemoreceptors in carotidarteries detects and communicates to medulla oblongata
increases frequency of impulses down accelerator nerve (sympathetic nervous system) to SAN
heart rate increases
increased blood flow allows increased CO2 to reach lungs to be removed quicker so CO2 levels decreases, and thus the pH returns to normal