circulatory system

• oxygen is carried by red blood cells
• haemoglobin + oxygen- oxyhaemoglobin
• the human circulatory system is made up of the heart, blood vessels and blood
• the heart is made of cardiac muscle
• the right side of the heart pumps blood to the lungs and back to the heart again. In the lungs the blood picks up oxygen and get rid of carbon dioxide
• The left side pumps blood to the rest of the body and back to the heart again then the blood delivers its oxygen and picks up carbon dioxide
• The wall of the left ventricle is thicker than the wall of the right ventricle because the left pumps blood to the whole body and the right only takes blood to lungs
• double circulation is when blood passes through the heart twice in one full circulation
• function of valves is to stop blood flowing in the wrong direction valves shut if blood tries to go backwards
• deoxygenated blood arrives at the right atrium from the vena cava
• the right atrium pumps the blood into the right ventricle
• the right ventricle pumps the blood into the pulmonary artery which carries the blood to the lungs to pick up oxygen
• the ocygenated blood is carried back from the lungs to the left atrium by the pulmonary vein
• the left atrium pumps the blood into the left ventricle
• the left ventricle pumps the blood into the aorta which carries the blood to the body cells
• The heart has four chambers - two atria and two ventricles
• blood is carried around the body in three different types of blood vessels- arteries, veins and capillaries
• the blood in arteries is carried at high pressure so have thick walls made of muscle and elastic fibre so they can cope with the pressure and have a small lumen
• veins carry blood back to the heart from around the body and the blood in them is not under pressure, so they have a thinner layer of muscle and elastic fibre have a large lumen because blood is at lower pressure and have valves to prevent backflow
• capillaries are much smaller than arteries and veins and are one cell thick lumen is very narrow they are permeable. Their function is to supply body with oxygen and glucose and also remove waste products like carbon dioxide and urea
• arteries carry oxygenated blood
• veins carry deoxygenated blood
• arteries carry blood away from the heart
• the more oxygen blood contains the brighter the color of the blood
• blood is composed of plasma, red blood cells, white blood cells, platelets
• plasma is a yellow liquid and contains digested food, waste chemical e.g. urea, blood proteins and hormones
• red blood cells are biconcave discs. this shape gives them a large surface area to volume ratio function is to carry oxygen and have no nucleus to carry more haemoglobin
• white blood cells are large cells with large or lobed nucleus. Their function is defense against diseases and can either produce antibodies or engulf bacteria
• platelets are cell fragments and contain substances that are involved in clotting the blood which reduces blood loss with cuts and keep cut clean by forming a scab
• heart attacks are caused when a coronary artery becomes blocked by cholesterol or fatty material. This cuts off the blood supply so the cells can no longer respire to produce energy
• risk factors include High salt intake, eating fatty foods, smoking, little exercise, inherited genes, age and gender
• White Blood Cell

  Large cells with either large or lobed nucleus. Their function is defense against diseases and can either produce antibodies or engulf the bacteria with enzymes
• Platelets


  Cell fragments that produce substances that are involved in the clotting of blood which reduces the loss in the case of a cut. clot hardens to form a scab which keeps it clean
• CHD


  heart attacks are caused when a coronary artery becomes blocked with cholesterol and cuts off the blood supply (glucose and oxygen)to heart muscle cells. This means cells can no longer respire to produce energy
• Risk Factors of CHD

  high salt intake,

  eating fatty foods

  smoking

  little exercise

  inherited genes

  age

  gender
• arteries

  blood carried at high pressure walls have thick layer of muscle and elastic fibre so they can cope with pressure. have small lumen
• veins


  carry blood back to heart blood isnt carried at high pressure so have a thinner layer of elastic fibre and muscle have large lumen have valves
• $oxygen +$$haemoglobin =$$oxyhaemoglobin$
• capillaries


  are much smaller than arteries and veins. walls are only 1 cell thick very narrow lumen and permeable. function is to supply body cells with glucose and oxygen remove waste products like carbon dioxide and urea
• Red blood cell

  are biconcave discs so have large surface area to volume ratio function is to carry oxygen have no nucleus so can carry more haemoglobin