Circulatory system

• Atriums are thin-walled chambers that receive blood from veins
• The heart has four chambers - two atria and two ventricles
• The heart is located between the lungs, behind the sternum (breastbone), and to the left side of the body.
• The right atrium receives deoxygenated blood from the body via the superior vena cava (SVC) and inferior vena cava (IVC)
• Veins - carry blood to the heart
• Artery - carry blood away from the heart
• Capillaries- connection between arteries & veins
• Red blood cells - transport oxygen
• White blood cells - fights infection
• Plasma - transport CO2 & nutrients
• Platelets- blood cougulation
• Blood enters the atria from veins
• Blood passes to the ventricles
• When ventricles contract the blood is transported into the arteries
• Aorta takes blood to the body, pulmonary artery takes blood to the lungs
• Valves close to stop blood from flowing backwards
• Arteries: high pressure against artery walls which stretch and shrink = pulse
• veins: contain valves to prevent blood from flowing backward
• Capillaries: smallest blood vessels, exchange gases and nutrients with tissues
• 45% cells - red cells & white cells
• Red blood cells : have haemoglobin - transport oxygen
• White blood cells : fight diseases, stop infections. Dies in the process and forms puss
• Ratio red cells : white cells = 500:1
• Platelets : fragments of cells, form blood clots to stop bleeding at site of injury
• 55% plasma, watery liquid, contains nutrients, hormone, urea and CO2
• Capillaries are thin and there are many of them, this provides a large surface area for diffusion
• Diffusion : movement of particles from an area of high concentration to an area of low concentration, down the concentration gradient
• Oxygen diffuses out of the alveoli into the capillaries
• oxygen diffuses out of the capillary into the cell
• Carbon dioxide is released in the body cells through a process called respiration
• The body needs to expel the carbon dioxide
• CO2 diffuses out of the cells into the capillaries
• Transported to the lungs (alveoli)
• CO2 diffuses out of the blood into the alveoli, breathed out
• Glucose diffuses through wall of small intestine into capillaries
• travels to the heart. Then to the lungs. Then back to the heart. Then to body cells : diffuses out of the capillaries into the body cells.
• heart beats 2.5 billion per lifetime
• Blood vessels are 100,000 km long
• Artery walls are elastic to expand/contract due to pressure
• Heart has its own arteries & veins, coronary artery / coronary vein