3.2.9- Heart Action: Initiation and Control Flashcards
What does myogenic mean?
Control of the basic heartbeat is myogenic, which means the heart will beat without any external stimulus
This intrinsic rhythm means the heart beats at around 60 times per minute
What is the sinoatrial node and what does it do?
The sinoatrial node (SAN) is a group of cells in the wall of the right atrium. The SAN initiates a wave of depolarisation that causes the atria to contract
What is the Annulus Fibrosus?
The Annulus fibrosus is a region of non-conducting tissue which prevents the depolarisation spreading straight to the ventricles
Where does the wave of depolarisation go after the Annulus Fibrosus?
The depolarisation is carried to the atrioventricular node (AVN)
This is a region of conducting tissue between atria and ventricles
After a slight delay, the AVN is stimulated and passes the stimulation along the bundle of His
This delay means that the ventricles contract after the atria
What is the Bundle of His and what does it do?
The bundle of His is a collection of conducting tissue in the septum (middle) of the heart. The bundle of His divides into two conducting fibres, called Purkyne tissue, and carries the wave of excitation along them
Where are the Purkyne fibres and what do they do?
The Purkyne fibres spread around the ventricles and initiate the depolarization of the ventricles from the apex (bottom) of the heart
This makes the ventricles contract and blood is forced out of the pulmonary artery and aorta
