1. The Cardiovascular System
1.2: The structure and functions of the cardio-respiratory system
Functions and structure of the cardiovascular system
Structure of the arteries, capillaries and veins
Mechanism required to redistribute blood flow
Function and importance of red and white blood cells, platelets and plasma
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2. The Cardiovascular System
It consists of:
Blood Vessels Heart
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Functions
Transports oxygen and nutrients - The heart pumps oxygen around the body which releases energy stored as glucose in cells and carries away waste products, also get nutrients such as amino acids and water to where they are needed
Helps the blood to clot – platelets form a scab to stop bleeding and heal a wound
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Functions
Controls temperature – when the body gets too hot blood vessels close to your skin get bigger (vasodilation), blood is diverted to the surface of your skin to allow heat to radiate out. If the body gets too cold the vessels get smaller and contract (vasoconstriction), blood is diverted away from the surface of the skin.
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5. The Chambers of the Heart
Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
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6. The Vessels of the Heart
Pulmonary
Artery
Aorta
Vena Cava
Pulmonary Vein
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The Valves of the Heart
Semi-Lunar Valves
Tricuspid Valve
Bicuspid Valve
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8. Other Components of the Heart
Septum
Muscular Wall
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How does the heart beat?
Stage 1: The top chambers (atria) relax and fill up with blood from the veins.
Stage 2: The atria contract and blood is forced into the relaxing bottom chambers (ventricles).
Stage 3: The ventricles contract and blood is forced out of the heart and into the arteries.
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How does the heart beat?
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11. Blood Flow – Pulmonary Circulation
Lungs
Pulmonary
Artery
Pulmonary Vein
Heart
Body
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12. Blood Flow – Systemic Circulation
Lungs
Aorta
Heart
Body
Vena Cava
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13. Deoxygenated blood is pumped from the heart to the lungs through the pulmonary artery.
Oxygenated blood returns to the heart through the pulmonary vein.
lungs
Oxygenated blood is pumped at high pressure from the heart to the body through the aorta.
Deoxygenated blood returns to the heart through the vena cava.
This simple plan shows the heart and the 4 main blood vessels.
Introduce the following:
Double circulatory system = (1) PULMONARY CIRCULATION (anything pulmonary should be associated with the lungs) between the heart and the lungs and back (2) SYSTEMIC CIRCULATION between the heart and the rest of the body’s systems and back to the heart.
Introduce the idea of the heart as a double pump – the right-hand side receiving and pumping deoxygenated blood, the left-hand side receiving and pumping oxygenated blood.
ARTERIES carry blood away from the heart, VEINS carry blood to the heart.
body’s
cells

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Task
Starting with the vena cava, write down the journey that the blood takes around the circulatory system.
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Blood Vessels
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Blood Vessels
Arteries carry blood AWAY from the heart and have a thick elastic muscle wall. They stretch as blood is pumped in and the muscle wall contracts to pump blood along. They do not have valves. High pressure.
Arteries
Veins
Capillaries
Veins carry blood BACK to the heart and have a thinner wall than arteries which is less elastic. The lumen is larger than the lumen in arteries. They have valves to help blood flow back. Low pressure.
Capillaries are one cell thick and it is here that gaseous exchange takes place. Oxygen and carbon dioxide diffuse across the capillary wall. Low pressure.
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Valves in Veins
Blood is under less pressure in the veins than in the arteries, so veins have valves to prevent the backflow of blood and help blood return to the heart. Valves only allow blood to flow in one direction.
Muscular contraction also squeezes blood in the veins and helps to return it to the heart.
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Blood Distribution
Redistribution of blood is also known as vascular shunting, blood is directed away from inactive areas to active areas of the body.
When you exercise, muscles need oxygen for energy so more blood is sent to them; vascular shunting.
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19. Vasoconstriction/Vasodilation
Vasoconstriction narrows the internal diameter of the arteries/arterioles supplying oxygenated blood to the inactive areas of the body.
Vasodilation widens the internal diameter of the arteries/arterioles supplying oxygenated blood to the active areas of the body.
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20. Vascular Shunting During Exercise
Inactive areas of the body, such as the digestive system experience vasoconstriction.
Active areas of the body, such as the working muscles, experience vasodilation.
As oxygen levels drop and lactic acid builds up the blood vessels widen (dilate) to make it easier to get oxygen to the working muscles.
The intensity of the exercise will have an impact on the redistribution of blood for example it will vary from periods of low intensity to periods of high intensity.
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Blood Pressure
Blood pressure is the force exerted by blood on the wall of the arteries.
Systolic blood pressure – max. pressure in the arteries when the heart contracts.
Diastolic blood pressure – the pressure of the blood during the relaxation phase between heart beats (at rest). This depends on the elasticity of the arteries.
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22. The Components of Blood
Plasma
Platelets
White Blood Cells
Red Blood Cells
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Plasma
90% water, the liquid part of blood
Contains sodium chloride (salt), glucose, antibodies, urea and other waste products,
Importance to sport – circulation ensures that oxygen transportation can take place and carbon dioxide mostly dissolves in plasma when it is being removed into the blood.
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Platelets
Stick together when blood vessels are cut to form a clot (thrombokinase)
Prevents blood leaving the body and bacteria entering it.
Rush to the site, swell and stick together to act as a plug.
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White Blood Cells
Protect the body from disease (leukocytes)
Destroy pathogens which cause illness, some completely engulf bacteria or viruses and digest them
Produce antibodies to attack disease.
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Red Blood Cells
They are flexible and dome shaped so they can pass through capillaries (erythrocytes)
Collect and carry oxygen to the muscles to create energy
Contain haemoglobin (red pigment) which combines with oxygen to become oxyhaemoglobin.
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