Cardiac cycle Flashcards
What is the cardiac cycle?
The cardiac cycle is the flow of blood in the heart.
How long does the cardiac cycle last?
The cardiac cycle lasts 0.8 seconds.
Explain the cardiac cycle.
The cardiac cycle is a systematical process which takes action within two parts. The contraction phase and the relaxation phase.
What is the contraction phase within the cardiac cycle?
The contraction phase of the ventricles (systole) lasts around 0.3 seconds.
What is the relaxation phase within the cardiac cycle?
The relaxation phase of the ventricles (diastole) takes around 0.5 seconds.
What are the four processes of the cardiac cycle.
Atrial diastole, ventricular diastole, atrial systole, ventricular systole.
Describe the processes of the cardiac cycle.
Atrial diastole - the atria of the heart fills with blood.
Ventricular diastole - ventricles also fill with blood via the tricuspid and bicuspid valves.
Atrial systole - atria contract and all blood is ejected into the ventricles and the atrioventricular valves close.
Ventricular systole - semilunar valves open and ventricles contract and blood is forced from the right ventricle to the pulmonary artery and blood from the left ventricle to the aorta.
The semi lunar valves close and the cycle is complete.
Why is the heart considered as a double circulatory pump?
The heart has a double circulation; the systemic and pulmonary as each side of the heart pumps in synchronisation. The cardiac cycle.
What is heart rate?
Heart rate (HR) is the heart contracting and relaxing to create a heart beat.
What is stroke volume?
Stroke volume (SV) is the volume of blood pumped out by each ventricle per contraction.
What is cardiac output?
Cardiac Output (Q) is the volume of blood pumped from the left ventricle in one minute.
What is the equation linking HR, SV and Q?
HR x SV = Q
What happens because the heart is myogenic?
Because the heart is myogenic, it does not need stimulation from the CNS to contract.
What are the four neural sites that work together to make the heart pump?
The sinoatrial node, the atrialventricular node, the bundle of his and purkinje fibres.
What is the sinoatrial node?
The sinoatrial node (SAN) is located in the top right of the right atria. It is known as the pacemaker which initiates the heart rate.
Where is the atrioventricular node?
The atrioventricular node (AVN) is located at the bottom of the right atrium.
Where is the bundle of his?
The bundle of his is located in the septum.
Where are the purkinje fibres?
The purkinje fibres are located within the bottom of the ventricles.
What is the process of the neural control of the cardiac cycle?
The SAN sends nerve impulses to both atria so they contract at the same time. These impulses travel to the AVN and then through the bundle of his and finally to the purkinje fibres which make the ventricles contract simulteanously.
What is the anticipatory rise?
The anticipatory rise is when your sympathetic nervous system releases adrenaline which increases your heart rate.
What is the function of chemoreceptors?
Once you begin to exercise, there is an increase of co2 and lactic acid. This is detected by chemoreceptors in the brain which triggers the SNS to release more adrenaline.
How does the conduction of nerve impulses increase?
As you exercise, the body becomes warmer; meaning the heart rate increases and the speed of conduction of nerve impulses also increases.
What is the function of the parasympathetic nervous system (PSNS)?
The PSNS is active during rest and reduces the heart rate by using the neurotransmitter Acetylcholine.
