16The trachea ( windpipe) is supported by rings of cartilage. Mucus catches dirt & bacteria and is carried to the top of the trachea by cilia.The mucus is then swallowed.
17BreathingBreathing is brought about by the muscles of the ribs (intercostal muscles) and the diaphram contracting & relaxing.During inspiration the volume of the chest cavity increases and air rushes in to fill the space.During expiration the volume of the chest decreases and air is pushed out.
21The Circulatory System The heart is a muscular pumpPumps blood around the bodySupplies all cells withFoodOxygenRemoves wastesCarbon dioxide
22Structure of the heart Valves prevent the backflow of blood The muscle of the left side is much thicker as it must pump blood all around the body.The muscle on the rightside is thinner. It only pumpsblood to the lungs
24Blood Vessels Arteries Veins Capillaries thick, muscular walls carry high pressure blood away from the heartVeinsthin, stretchy, muscular wallsreturn low pressure blood to the heartValves prevent backflow of bloodCapillariestiny blood vesselsconnect arteries and veinscarry blood to the cells of the body
25The Coronary ArteryLeads from the aorta - supplies blood to heart muscle.Blockage can result in a heart attack
26The Blood Blood is made up of: Plasma – liquid which carries cells and dissolved substancesRed blood cells – carry oxygenWhite blood cells – fight infectionPlatelets – help clot blood
27Gas ExchangeAs blood flows through capillaries oxygen diffuses from the blood into the cells.Carbon dioxide from the cells diffuses into the blood and is carried away.Blood high inoxygenBlood high in carbondioxide.
28Capillary NetworksTo allow efficient gas exchange the capillary network has:A large surface areaVery thin cell walls
29Haemoglobin Red blood cells contain haemoglobin. This combines with oxygen in the lungs to form oxyhaemoglobin.As the blood passes through cells which have low oxygen levels the oxyhaemoglobin releases the oxygen which can then be used by the cells.
32The structure of the eye: Cornea - focusing of light.Lens - fine focuses the light onto the retinaIris - controls the size of the pupil, controling the amount of light entering the eye. Retina - layer of light sensitive cells where an image is formed.Optic nerve - carries the nerve impulses to the brain.Blind spot – where the optic nerve meets the retina – no image is formed here.
33Binocular Vision Using two eyes allows us to judge distance. This is called binocular vision.
43Muscle FatigueMuscle fatigue occurs due to the build up of lactic acid in muscles that are exercising.Lack of oxygen results in anaerobic respiraton which causes lactic acid to form.
44Anaerobic Respiration Only a little energy is released.During rest oxygen is needed to remove the lactic acid formed.This is known as the ‘oxygen debt’.
45Exercise Exercise causes the heart rate & breathing rate to increase. Allows more blood carrying sugar & oxygen to be supplied to muscles.The time taken for these to return to normal following exercise is the RECOVERY TIME.
46Fitter people have a shorter recovery time than unfit people. They also have lower levels of lactic acid production.Recovery time can be improved by regular exercise