2 Providing for the cell’s needs The cell theory states that all living organisms are made up of cells or substances produced by cells.All cells need nutrients eg glucose and oxygen in order to function properly, be active and grow.The cells use the nutrients and produce wastes eg carbon dioxide that must be removed as they can be toxic and damage the cells.The process that provides energy for the activity of cells is cellular respiration. The formula for cellular respiration is:glucose + oxygen carbon dioxide + water + ENERGYC6H12O6 + O2 CO2 + H2O + Energy (ATP + waste heat)
3 Why we need organ systems Organisms which are single-celled or very small and thin (less than 1 mm) can exchange materials through their body surfaces.Because most multi-cellular organisms are too large for exchange of nutrients and wastes to occur through their body surfaces, they need organs to allow this exchange. Most multi-cellular organisms have organs arranged in systems to do this:A transport system - called the circulatory system to bring these nutrients to the cells, and to carry away wastes,A system to allow exchange of oxygen and carbon dioxide - called the respiratory systemA system to obtain nutrients - called the digestive systemA system to deal with and remove wastes from the body - called the excretory system
4 Open circulatory systems Open systems have one or more pumps (hearts) and tubes that empty into body cavities. The fluid (haemolymph) can leave the vessels.Found in smaller invertebratesInsectCrustaceanMollusc
5 Closed circulatory systems Closed systems have one or more hearts and blood vessels that feed back to the heart. The fluid (blood) does not leave the vessels.Found mainly in the vertebratesThe number of chambers in the heart varies
6 What is a closed circulatory system? The circulatory system carries blood and dissolvedsubstances to and from different places in the body.The Heart has the job of pumping these things aroundthe body.The Heart pumps blood and substances around thebody in tubes called blood vessels.The Heart and blood vessels together make up theCirculatory System.
7 Aorta - Artery to Head and Body Pulmonary artery - Vein from Lungs The Mammalian HeartPulmonary artery - Artery to LungsAorta - Artery to Head and BodyPulmonary artery - Vein from LungsSuperior vena cava - Vein from Head and BodyRight AtriumLeft AtriumSemi lunar valvesRight atrioventricular valve (tricuspid)Left atrioventricular valve (bicuspid)Right VentricleLeft Ventricle
8 Mammalian circulation Arterioles branch into capillariesGas exchange occurs across capillaries, whose walls are one cell thickCapillaries connect to venulesVenules connect to veinsVeins return blood to the heartBlood flows out of and away from the ventricular chambers via arteriesArteries branch into arterioles
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