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 N. Walker GCSE PE Edexcel N. Caton GCSE PE Edexcel

The Cardiovascular System It consists of: Blood Vessels Heart N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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 N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

The Chambers of the Heart Left Atrium Right Atrium Left Ventricle Right Ventricle N. Walker GCSE PE Edexcel

The Vessels of the Heart Pulmonary Artery Aorta Vena Cava Pulmonary Vein N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel The Valves of the Heart Semi-Lunar Valves Tricuspid Valve Bicuspid Valve N. Walker GCSE PE Edexcel

Other Components of the Heart Septum Muscular Wall N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel How does the heart beat? N. Walker GCSE PE Edexcel

Blood Flow – Pulmonary Circulation Lungs Pulmonary Artery Pulmonary Vein Heart Body N. Walker GCSE PE Edexcel

Blood Flow – Systemic Circulation Lungs Aorta Heart Body Vena Cava N. Walker GCSE PE Edexcel

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

N. Walker GCSE PE Edexcel Task Starting with the vena cava, write down the journey that the blood takes around the circulatory system. N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel Blood Vessels N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

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. N. Walker GCSE PE Edexcel

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. N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

The Components of Blood Plasma Platelets White Blood Cells Red Blood Cells N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel

N. Walker GCSE PE Edexcel 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. N. Walker GCSE PE Edexcel