Definitions Flashcards
Myogenic
The capacity of the heart to generate its own impulses
Sinoatrial node
A small mass of cardiac muscle found in the wall of the right atrium that generates the heartbeat (pacemaker)
Atrioventricular node
Node that relays the impulse between the upper and lower sections of the heart
Systole
When the heart contracts
Bundle of his
A collection of heart muscle cells that transmit electrical impulses from the av node via the bundle branches to the ventricles
Purkinje fibres
Muscle fibres that conduct impulses in the walls of the ventricles
Sympathetic system
A part of the autonomic nervous system that speeds up heart rate
Parasympathetic system
A part of the autonomic system that decreases heart rate
Medulla oblongata
Part of brain that regulates processes that keep us alive e.g breathing and hr
Chemoreceptors
Detect changes in blood acidity which is caused by an increase or decrease in the concentration of co2
Baroreceptors
Detects changes in blood pressure to either increase or decrease hr
Proprioreceptors
Sensory nerve endings that detect changes in muscle movement
Adrenaline
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which causes an increase in hr
Stroke volume
The vol. of blood pumped out by the heart ventricles in each contraction
Diastole phase
When the heart relaxes to fill with blood
Ejection fraction
The percentage of blood pumped out by the left ventricle per beat
Cardiac output
The vol. of blood pumped out by the heart ventricles per minute
Starlings law
Increased venous return = greater diastolic filling of heart = cardiac muscle stretched = more force of contraction = increased ejection fraction
Venous return
The return of blood to the right side of the heart via the vena cava
