Biology Revision

1. Biology Revision B5 The Living Body

2. 5a In good shape • Skeletons • No skeleton – e.g. worms • Exoskeleton – e.g. insect made of chitin • Endoskeleton – e.g. shark made of cartilage; human bone with some cartilage • Advantages of endoskeleton: • Framework of body • Can grow with body • Easy to attach muscles • Flexibility Human skeleton starts as cartilage by is ossified by the addition of calcium & phosphorus. Amount of cartilage present determines growth stage

3. 5a In good shape • Long bone structure: • Head covering of cartilage • Shaft, bone marrow with blood vessels • Cartilage & bone are living tissue • Bones are strong but easily broken • Types of fractures: • Simple • Compound • Green stick

4. 5a In good shape • Joints • Where 2 or more bones meet • Joined by ligaments • Bones moved by muscles, attached by tendons • Synovial joints e.g. ball & socket, hinge Advantages & disadvantages of joint replacement?

5. 5a In good shape • The arm • Biceps & triceps are antagonistic muscles • Arm is like a lever: • Biceps contract, triceps relax -> arm raises

6. 5b The vital pump • Circulatory Systems • None – e.g. amoeba • Open – e.g. insects • Closed – single e.g. fish , 2 chambered heart • Double e.g. mammals, 4 chambered heart • Historical contributions about circulatory system: • Galen – 200AD – believed blood flowed between heart & liver • Harvey – 1628 – discovered blood vessels, valves & high pressure blood flows away from heart in arteries

7. 5b The vital pump • Cardiac Cycle – controlled by SAN & AVN • ECG • Effect of adrenaline? • Exercise?

8. 5c Running repairs • Heart Conditions/Diseases • Lifestyle risk factors– diet, alcohol smoking, stress, drugs

9. 5c Running repairs • Blood components • Blood groups: A, B, AB, O • Rhesus positive & negative • Agglutinins – markers on the surface of red blood cells which make them Clump if they contact the corresponding antigen:

10. 5c Running repairs • Blood donation – cards for everyone? Religious objections? • Blood Clotting occurs: • When blood vessels are damaged • When blood comes into contact with air • To prevent too much blood being lost • To prevent pathogens entering through wounds • Vitamins K & C are needed for healthy blood clotting • Alcohol & cranberries slow it down • Anti-coagulant drugs e.g. warfarin, heparin & aspirin reduce it • Haemophilia is an inherited disease where a faulty protein stops blood clotting

11. 5d Breath of life • Gas Exchange • Simple organisms e.g. amoeba through skin • Complex organisms through specialist organs • Fish gills Respiratory System

12. 5d Breath of life • Breathing Volume of chest cavity increases, pressure in lungs falls Volume in chest cavity decreases, pressure in lungs rises

13. 5d Breath of life • Measuring Breathing • Tidal air/volume – volume of air in a normal breath • Vital capacity – maximum volume breathed in & out • Residual air/volume – air that remains in lungs • Respiratory Diseases • Industrial e.g. asbestosis • Genetic e.g. cystic fibrosis • Lifestyle e.g. lung cancer • Pathogenic e.g. pneumonia Asthma – irritated bronchioles narrow, muscles tighten, more mucus produced

14. 5e Waste Disposal • Excretion – getting rid of waste e.g. CO2, urea, sweat • Defecation – getting rid of solid waste through the anus • Excretory organs: lungs, kidneys, liver, skin • Skin structure: • Excess water & salt are excreted as sweat, which evaporates

15. 5e Waste Disposal • Kidneys Ultrafiltration – at bowman’s capsule – small molecules squeezed out under pressure Selective reabsorption – in tubules & loop of Henle – useful substances reabsorbed into blood

16. 5e Waste Disposal • ADH – controls reabsorption of water in kidneys • Made in pituitary gland • Negative feedback: • Water content low -> ADH released -> nephron tubules more permeable -> normal water level • Dialysis Machine • Waste diffuses from blood into dialysis fluid • Sodium & glucose in blood replaced

17. 5f Life goes on • Fertilisation – fusion of a male & female gamete • Reproductive systems:

18. 5f Life goes on • Menstrual Cycle • Day 1-5 – menstruation • Day 14 – ovulation

19. 5f Life goes on • Infertility • Fertility drugs – FSH injected to stimulate egg release • Artificial insemination • Egg donation – problem? Only has genes from one parent • Ovary transplant • Surrogacy – problem? Emotional attachment • IVF – problem? low success rate, twins/triplets more likely • Foetal Screening – for health of baby • Ultrasound • Anmiocentesis – tests cells from amniotic fluid using hypodermic needle, Ethical issues? Can cause miscarriage (1 in 200), termination?

20. 5g New for old • Organ Donation • Biological replacement e.g. blood, cornea, heart, lungs, kidney & bone marrow • Organs must be: healthy, right size & age, tissue matched • Can be from living donors e.g. kidneys or dead donors if they cannot regain consciousness & breath unaided • Mechanical replacement e.g. Kidney, knee & hip joint, heart, eye lens

21. 5h Size matters • Growth – animals grow in the early stages of life, plants grow continually in areas called meristems e.g. shoot tips • New cells for growth made by mitosis • Human growth stages: • Infancy (up to 2) • Childhood (2 -11) • Puberty (11-15) • Adulthood (15 – 65) • Old age (over 65) • Problems of living longer? Growth is measured as gain in height & mass Determined by: Genes Diet Exercise Hormones Health/disease Human growth hormone – made in pituitary gland – releases energy for growth from fat stores, stimulates growth of long bones