control of the heart rate Flashcards
cardiac muscle is myogenic, what does this mean
it can contract and relax without receiving signals from nerves
where does the process start
in the sinoatrial nerve (SAN) which is located in the wall of the right atrium
what does the SAN do, what is it similar to
like a pacemaker which sets the rhythm of the heartbeat by sending out regular waves of electrical activity along the atrial walls
what does the wave of electrical activity from the SAN cause in the heart
it causes the atria to contract at the same time
what prevents the electrical activity from being passed directly from atria to the ventricles
non-conducting collagen tissue
where are the electrical waves transferred to
into the atrioventricular node (AVN)
what is the atrioventricular node responsible for
passing the waves of electrical activity on to the bundle of His
why Is there a slight delay before the AVN reacts
to make sure the atria have emptied before the ventricles contract
what is the bundle of His
a group of muscle fibres responsible for conducting the waves of electrical activity between the ventricles to the apex of the heart
what is the apex of the heart
the bottom of it
what is the purkyne tissue
where the bundle of His splits into finer muscles fibres at the apex in the right and left ventricle walls
what does the purkyne tissue do
carries the electrical activity into the muscular walls of the right and left ventricles which causes them to contract simultaneously from the bottom up
what is the rate at which the SAN fires electrical impulses controlled by
unconsciously controlled by part of the brain called medulla oblongata
what are baroreceptors, where are they located and what stimulates them
pressure receptors in the aorta and the carotid arteries which are stimulated by high and low blood pressure
what are chemoreceptors, where are they located and what is their function
chemical receptors in the aorta, the carotid arteries and in the medulla, they monitor the oxygen level in the blood and also carbon dioxide and pH.
if the body detects high BP, high blood O2, low CO2 or high pH levels what happens
the baroreceptors or chemoreceptors detect this and an impulse is sent to the medulla which sends an impulse along the parasympathetic neurone, acetylcholine is secreted which binds to the receptors on the SAN to fix the problem
if the body detects low BP, low blood O2, high CO2 or low pH levels what happens
the baroreceptors or chemoreceptors detect this and an impulse is sent to the medulla which sends an impulse along the sympathetic neurone, noradrenaline is secreted which binds to the receptors on the SAN to fix the problem
