Describes the function of the left and right side of the heart.
Definitions and explanations of the cardiac cycle, stroke volume, cardiac output, circulatory system.
Cardiac cycle covers - filling, isovolumetric contraction, ejection, isovolumetric relaxation
covers:
-control of heart ra...
Control of the heart is done -intrinsic mechanisms within the heart
-nervous input from the CNS.
CVS= enclosed transportation loop that is driven by pressure.
Right side of the heart carries
deoxygenated blood to the lungs, the diffusion pathway is 0.3 micrometres. Blood
goes into the right heart through the vena cava and leaves through the pulmonary
arteries.
Left side of the heart pumps oxygenated blood to the rest of the body, the blood
moves from the pulmonary circulation to the systemic circulation. Blood goes into the
heart through pulmonary vein and it leaves through the aorta.
Vena cava right heart pulmonary artery
Pulmonary vein Left heart aorta
Cardiovascular system distributes 4.5 -5.5 litres of blood.
The cardiac cycle: is the duration of one heartbeat. It’s the start of a contraction to
the beginning of the next contraction.
At 60BMP the cardiac cycle is approximately 1 second in duration.
Stroke volume: volume of blood that is ejected from the heart during each cycle. If a
ventricle contains 100ml of blood at the end of filling, and 40ml of blood after
contraction, it means the volume ejected (therefore the stroke volume) is 60ml.
Volume of blood after filling – volume of blood after contraction = SV.
Cardiac output: total volume of blood that is pumped from the ventricle per minute.
CO = SV* HR.
64% of the blood is found in the veins.
The circulatory system consists of the heart and blood vessels (arteries, capillaries
, and veins). There are 2 circuits in series
-Pulmonary circuit is involved in the reoxygenation of blood
-Systemic circuit which is involved in the transport of blood around the body.
The lungs contain alveoli which contain capillaries. Oxygen gets transported out of
the alveoli and into the capillaries to be transported in the body.
Arterioles are the site for the greatest regulation of blood pressure. In the arteries the
blood pressure is approx. 90mmHg, whereas in the
capillaries its decreased to 10mmHg.
Capillaries are found close to the tissues/ end organs.
To calculate the mean arterial pressure, you assume
that the heart is contracted 1/3rd of the cardiac cycle, and
relaxed 2/3rds of the cardiac cycle.
Mean arterial pressure 1/3 of the systolic pressure, plus
2/3rd of the diastolic blood pressure.
- Blood enters the atria the contraction of the atria causes it to move into the
ventricles. As it flows into the ventricles the pressure inside becomes greater than
the pressure of the atria, causing the closing of the atrioventricular valves (AV
valves) to prevent the back flow of blood. Contraction of the ventricles cause an
increase in pressure and opening of the semi lunar valves. This allows blood to be
ejected out the pulmonary artery (right side of the heart) or the aorta (left side of the
heart).
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