circulatory system

• functions of the circulatory system

  • circulate blood through the body
  • transports water, oxygen and fluid to cells and removes wastes away from cells
  • helps maintain correct body temperature
  • helps fight disease
• components of circulatory system

  • heart
  • blood vessels
  • blood
• arteries - carry oxygenated blood away from the heart (except pulmonary artery)

  • blood is under high pressure in arteries
• veins - carry deoxygenated blood to the heart (except pulmonary veins)

  • pumped up towards heart using muscular contractions and valves
• capillaries - permeable thin walls that enable movement of O2, CO2 and nutrients

  • surrounds structures like muscles and organs
  • dilate - expand
  • vasoconstrict - shrink
• deoxygenated blood travels into the right atrium from the upper body via the superior vena cava and inferior vena cava. It passes through the tricuspid valve into the right ventricle, then through the pulmonary valve into the pulmonary artery which takes the deoxygenated blood into the lungs where it is oxygenated. The oxygenated blood then travels back into the left atrium via the pulmonary veins, through the mitral valve into the left ventricle and through the aortic valve into the aorta where it is dispersed throughout the body to provide oxygen to the body.
• red blood cells - contains haemoglobin that carries oxygen and gives blood red colour
• white blood cells - can pass through capillary walls to fight diseases by absorbing them
• platelets - cause blood to clot to seal wounds
• plasma - clear yellowish fluid substance of blood of which 90% is water
• stroke volume - the amount of blood the heart pumps out with each beat
• cardiac output - the amount of blood the heart is able to circulate in one minute
• blood pressure - an indication of the pressure of blood against the artery walls

  • systolic - heart contracts
  • diastolic - heart rests