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Structure & Function of the Heart - Coggle Diagram
Structure & Function of the Heart
The semilunar valves stop the backflow of blood into the heart.
Blood vessels leading in and out of the heart
Aorta - carries oxygenated blood away from the left ventricle to the body
Vena Cava - carries deoxygenated from the body back to the heart
Pulmonary Artery - carries deoxygenated blood away from the right ventricle to the lungs
Pulmonary Vein - carries oxygenated blood from the lungs to the heart
CO = HR x SV
Cardiac output = heart rate x stroke volume
Cardiac Cycle
Refers to the pattern of contraction and relaxation during one heartbeat
Contraction of the heart is known as systole and relaxation of the heart is known as diastole
Cycle
2.
Atrial Systole - atria contract and remaining blood is pushed into ventricles
3.
Ventricular Systole - ventricles contract and push blood out through the aorta and pulmonary artery
1.
Atrial and Ventricular diastole - chambers are relaxed and filling with blood
Cardiac Conduction System
The heartbeat starts starts because of the sino-atrial node (SAN)
The SAN is located on the wall of the right atrium and sets the rate at which the heart contracts
The SAN sends out electrical signals which are carried through the muscular walls of both atria - these impulses cause atrial systole
The impulse is passed to the atrio-ventricular node (AVN)
Once the impulse from SAN reaches the AVN the impulse is passed to the conducting fibres which travel down the central wall of the heart
The impulse then splits and travels up the left and right ventricles - causing them to contract simultaneously (ventricular systole)
Blood Pressure
Blood pressure increases during ventricular systole and decreases during diastole
Blood pressure can be measured using a sphygmomanometer
A syphygmomanometer measures systolic and diastolic value
Average blood pressure is 120/80 mmHg
High blood pressure is known as hypertension
Hypertension is a major risk factor for developing many cardiovascular disease
Autonomic and Hormonal Control
The heart rate activity can be altered by the activity of hormones and the nervous system
The medulla regulates the heart rate of the SAN through the antagonistic actions of the autonomic nervous system (ANS)
Two antagonistic nerves:
Sympathetic releases noradrenaline which increases the heart rate
Parasympathetic releases acetlycholine which decreases the heart rate