Biology - The circulatory system

• Blood is pumped away from the heart at high pressure in arteries, and returns to the heart at low pressure in veins.
• The human circulatory system is a double circulatory system.
• The main blood components are: Red blood cell, White blood cell, and Platelets.
• The red blood cell's function is to carry oxygen and it contains haemoglobin (rich in iron) to carry oxygen.
• The red blood cell has a biconcave shape to provide a large surface area for the diffusion of oxygen.
• The red blood cell has no nucleus to provide more space for haemoglobin.
• The white blood cell's function is to defend the body against disease and it contains a nucleus.
• The white blood cell has large cells that contain a nucleus.
• There are two types of white blood cells: Lymphocytes, which make antibodies, and Phagocytes, which engulf and digest microorganisms.
• The platelet's function is to convert fibrinogen to fibrin and fibrin forms a mesh that traps blood, making it important in blood clotting and scab formation.
• The circulatory system has three main components: Blood, Blood vessels, and The heart.
• The circulatory system has two main functions: Transportation of substances and Protection against disease.
• Blood is pumped away from the heart at high pressure in arteries, and returns to the heart at low pressure in veins.
• The human circulatory system is a double circulatory system.
• The blood vessels include arteries, veins, and capillaries.
• Arteries usually carry oxygenated blood from the heart to the rest of the body.
• The pulmonary artery carries deoxygenated blood from the heart to the lungs.
• Veins usually carry deoxygenated blood from the body back to the heart.
• The lumen is the central cavity of a hollow structure in an organism or cell.
• The pulmonary vein is one of the four veins that carries oxygenated blood to the heart from the lungs.
• Blood is moving at a low pressure in veins, so the walls are thin and there are few muscle and elastic fibres because blood does not surge through veins.
• Valves are present in veins to prevent the backflow of blood.
• Capillaries allow the diffusion of substances (e.g. oxygen, carbon dioxide, dissolved food and urea) between the blood and the body’s cells or vice versa.
• Capillaries have walls that are 1 cell thick providing a thin, permeable surface for diffusion.
• Blood is pumped away from the heart at high pressure in arteries, and returns to the heart at low pressure in veins.
• The human circulatory system is a double circulatory system.
• The blood vessels, the heart, and the effects of exercise are components of the circulatory system.
• The heart is a unidirectional pump.
• Valves are present to prevent the backflow of blood.
• The right side of the heart pumps deoxygenated blood to the lungs, which is low in oxygen and high in carbon dioxide.
• The left side of the heart pumps oxygenated blood to the organs of the body, which is high in oxygen and low in carbon dioxide.
• Deoxygenated blood enters the right atrium from the vena cava.
• Blood moves into the right ventricle.
• Blood is pumped into the pulmonary artery.
• The pulmonary artery carries deoxygenated blood to the lungs.
• The blood becomes oxygenated in the lungs.
• Oxygenated blood leaves the lung via the pulmonary vein.
• Blood enters the left atrium.
• Blood moves into the left ventricle.
• Blood is pumped into the aorta, which carries oxygenated blood around the body.