Unit Two - Key Area 6 Flashcards
What is the cardiac cycle?
the pattern of contraction (SYSTOLE) and relaxation (DIASTOLE) of the heart muscle in one complete heartbeat.
What is the calculation for cardiac output?
CO = SV x HR
What happens during diastole?
During diastole, blood returning to the atria flows into the ventricles. In diastole the pressure in the arteries closes the semi-lunar valves.
What happens during atrial systole?
Atrial systole transfers the remainder of the blood through the atrio-ventricular (AV) valves to the ventricles.
What happens during ventricular systole?
Ventricular systole closes the AV valves and pumps the blood out through the semi-lunar (SL) valves to the aorta and pulmonary artery.
What are responsible for the heart sounds?
the opening and closing of the semi lunar and the atrio
ventricular valves
Where is the Sino atrial node located?
the wall of the right atrium
What is the role of the SAN?
sets the rate at which the heart contracts
Where is the atrio-ventricular node located?
the centre of the heart
What is the role of the AVN?
Impulses from the AVN travel down fibres in the central wall of the heart and then up through the walls of the ventricles, causing ventricular systole.
What is the function of the medulla?
The brain’s medulla regulates the rate of the sino-atrial node through the antagonistic action of the autonomic nervous system (ANS).
What does the sympathetic nerve do?
releases noradrenaline which increases blood flow
What does the parasympathetic nerve do?
releases acetylcholine which decreases heart rate
What is hypertension?
high blood pressure
