Biology B5 2.0 / 5 based on 1 rating ? BiologyGCSEOCR Created by: Mollie DerhunCreated on: 30-01-13 17:55 SKELETONS Humans have an internal skeleton made of living cartilage and bone, both of which can repair themselves The human skeleton starts off as cartilage but becomes ossified (turned into bone) by the addition of calcium and phosphorous Ball and socket joints and hinge joints are synovial joints The biceps and triceps muscles are antagonistic muscles in the arm 1 of 5 BLOOD & CIRCULATION Galen realised the importance of the pulse and the heart being a pump. Harvey realised that the blood circulated throughout the body A 'hole in the heart' is a hole between either the two atria or two ventricles Oxygenated and deoxygenated blood are mixed up, so the blood carries less oxygen Blood can be donated and transfused A mismatch of blood groups can cause agglutination Humans have a closed, double circulation Fish have a closed, single circulation Drugs sich as warfarin, heparin and aspirin can be used to control clotting Heart rate is linked to activity. Heart muscle contraction is controlled by the pacemakers Some heart problems require a heart transplant, artificial valves or an arificial pacemaker Transplants may cause a rejection reaction and immuno-suppressive drugs are required Supply of donor organs is limited by shortage of donors, tissue match, size and shape of organs. 2 of 5 RESPIRATION Gaseous exchange takes place in the alveoli by diffusion Industrial, genetic and lifestyle choice factors cause lung diseases Methods of gaseous exchange limit amphibians and fish to their habitats Breathing difficulty, wheezing and a tight chest are symptoms of athsma Carbon dioxide is toxic at high levels in the blood 3 of 5 DIGESTION Due to specific enzyme requirements, the stomach contents are acidic and the small intestine is alkaline Small digested food molecules are absorbed into the blood by plasma or lymph Carbohydrase breaks down carbohydrates, protease breaks down protein and lipase breaks down fats Starch is broken down to maltose and then to glucose 4 of 5 REPRODUCTION & GROWTH Hormones (oestrogen, progesterone, FSH and LH) control the menstrual cycle Foetal development can be checked by amniocentesis and chromosome analysis Human growth hormone is produced by the pituitary gland Negative feedback mechanisms control hormone production Different parts of a foetus and baby grow at different rates Life expectancy has increased in recent times 5 of 5
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