gcse science biology unit B5 cards

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  • Created by: charlie
  • Created on: 06-06-13 13:16

bones and cartilage

job of skeleton:

  • provide framework and support 
  • aid movement 
  • protect vital organs 
  • some insects have external skeletons
  •  vertebrates- internal skeleton + backbone

advantages to internal skeleton:

  • easily grow with body and attach muscles to it  
  • more flexible than external skeleton and gives body support and framework 

bones made up of living cells- grow and repair themselves 

  • long bones - hollow and light - middle filled with bone marrow to make red BC 
  • start as cartilage in womb- calcium and phosphorus deposits make bone- ossification

can get damaged- osteoporosis in elderly- little calcium so brittle and weak bones 

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joints and muscles

  • synovial joints are the main type
  • bones held together by ligaments (high tensile strength+elastic)
  • ends covered in cartilage (stop rubbing+shcok absorber)
  • synovial membrane releases synovial fluid to lubricate joint 

2 types: ball and socket(hip+shoulder) hinge (knee+elbow)

  • bones attached to muscles to move them 
  • muscles usually come in antagonistic pairs 
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circulatory system

single-celled organisms:

  • materials just diffuse in and out 

multicellular organisms 

  • larger and need blood circulatory system- transport mineral efficiently around body 
  • heart acts as pump 
  • arteries highest pressure, capillaries medium pressure, veins lowest pressure 

animals with gills have single c. system 

  • one circuit from heart 
  • two chambered heart- one to receive and one to pump 

humans have double c. system 

  • one to lungs and one to body 
  • need four chambered heart- blood pumps separately whilst maintaining high pressure 
  • unborn babies have hole in heart- get oxygen from mother (placenta) gap between atria allows blood to bypass lungs 
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history of the heart

Galen (ancient greece):

  • knew about chambers 
  • believed constant arterial blood made by heart and blood in veins made by liver and were consumed by organs 

William Harvey (1578-1657):

  • heart valves stopped back flow of blood 
  • heart pump and pulse caused by pumping into arteries 
  • same blood circulated 
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heart rate

affected by:

  • exercise 
  • hormones- adrenaline when shock or danger- 'fight or light' response making sure muscles have oxygen 


  • electrical current tells heart how fast to beat causing contraction of muscles
  • two clusters: 
  • sino-atrial node - contracts first + simulates AVN to contract 
  • atrio-ventricular node 
  • artificial pacemaker- implanted under skin and wire going to heart 

electrocariogram- shows electical acitivty of heart:

  •  show heart attacks, irregular heartbeats and general health 


  • show enlarged heart(heart failure), dec. pumping ability(cardiomyopathy), valve function
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heart disease

hole in the heart:

  • gap in wall separating eith two ventricle or atria- causing oxygen+deoxygen blood to mix 
  • reduces amount of blood pumped to body- corrected by surgery 

valve damge: 

  • damaged or weakened by heart attacks, infection or old age 
  • valve not to open properly- high BP 
  • valve allows back flow- no circulation and low BP 
  • replaced through surgery and artificial one fitted 


  • coronary arteries blocked with fatty deposits resulting in heart attack
  • coronary bypass operation- take blood vessel from elsewhere and use it to bypass arteries

artficial parts used over living 

  • not seen as foreign and rejected+less drastic procedure compared to transplant 
  • however needs replacing as do not last very long 
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blood clotting and transfusions

sometimes blood doesnt clot properly:

  • clot is mesh of protein fibres called fibrin fibres- plugs damaged area 
  • clots fromed by series of chemical reactions- take place when platelets exposed to damaged blood vessels 
  • too much clotting- storkes or Depp Vein Thrombosis
  • too little clotting- bleed to death
  • drugs taken to reduce risk- warfarin, heparin, aspirin
  • haemophilia- genetic condition blood doesnt clot easily due to missing clotting factor- can be injected 

blood types important in transfusions 

  • letters refer to type of antigen on surface of persons red BC 
  • anit-A meets A antigen blood clumps together- agglutination 
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transplants, organ donation and replacement

organs can come from living or  dead donors and must meet certain criteria:

  • young so organ fit and healthy 
  • similar body weight and close tissue match so organ is good fit and no rejection 
  • living donors over 18 + donors who recently dies must have family consent

transplants rejected and ethical issues 

  • immune system sees as foereign and rejects- similar tissue match+immuno-suppressive drugs help but pateient becomes veulnerable to infections 
  • body should be buried intact+death up to god, doctors might not save, people pressured 

problems with supply of donor organs 

  • made easier by and opt-out system - still large criteria but shorted time as more donors 

mechanical replacments 

  • heart-lung machines- blood oxygenated+pumping during heart/lung surgery 
  • kidney dialysis- fliters patients blood- waiting for transplant 
  • mechanical ventilators- push air in and out of lungs when patient stopped breathing 
  • problems- large, power supply, materials wont harm body/degrade sometimes reactions 
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the respiratory system

CO2 waste product of respiration- high level CO2 toxic- brain detects rise+inc. breathing

rate ventilation uses msucles:

  • inspiration: intercostal muscles+diaphragm contract flattening down + inc. vol. of throax 
  • expiration :intercoastals+diaphragm relax moving up+inc pressure outside lungs air forced out

lung capacity measured with spirometer - monitor lung diseases 

  • total vol. of air you can fit in lungs is total capacity 
  • vol. of air breathed in+out in one breathe(tidal vol.)- some air left-lungs stay open(residual air)
  • total lung capacity - residual air = vital capacity air (max. vol breathed in and out)

humans- gaseous exchange in lungs 

  • blood passing next to alveoli- returned from body- lots of CO2 diffuse into lungs+O2 out 
  • blood reaches body cells- O2 released+diffuses into body cell- CO2 diffuses out 

alveoli adapted

  • large SA, moist O2+CO2 dissolve, permeable surface, thin lining, good blood supply 

other organisms exchange diff

  • amphibians- gaseous exchange- permeable skin+lungs- skin kept moist(not waterproof)
  • fish- gaseous exchange- gills- moth open for O2 water and flows over gills when closed , water support gills 
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lung disease

  • trachea+bronchi lined with mucus+cilia catch dust+microbes before reaching lungs 
  • cilia beat pushing microbe filled mucus out of lungs 
  • lungs prone to infections- dead end so microbes cant be easily flushed out 

lungs disease causes 

  • industrial materials- asbestos (roof insulator)- inflammation+scarring limiiting gas exchange

genetic causes

  • cystic fibrosis- inherited- thich, sticky mucus clogs up brochioles- breathing difficult 

lifestyle causes 

  • smoking- lung cancer- cells divide out of control+form tumour recucing lung SA


  • lungs overly sensitive- muscles around bronchioles contract- constricting airways- inflamed+fluid builds up- asthma attack (difficult breathing, wheezing, tight chest), inhaler is a muscle relaxant- no cure 
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  • breaking larger insoluble molecules into smaller soluble molecules- absorb into blood plasma/lymph 
  • 1) physical digestion- chewing+churning - produce large SA 
  • 2)chemical- enzymes bilogical catalyst- allow molecules to pass through cell membranes

three mains types of digestive enzymes:

  • 1) carbohydrases- big carbs (starch) into simple sugars in mouth+small intestine- 2 step process starch--maltose--glucose 
  • 2)proteases- proteins into amino acids in stomach+small intestine 
  • 3)lipases- fats into fatty acids+glycerol in small intestine 

enzymes need righ conditions- pH in stomach (acidic), s. intestine + mouth (alkaline)

bile improves fat digestion (made in liver, stored in gall bladder):

  • break down fat- tiny droplets- larger SA(emulsification)-- alkaline+neutralises for s.intestine

food molecules absorbed into blood by diffusion

  • glucose+amino acids small enough to diffuse into blood plasma + travel where needed 
  • fat- diffuse out of intestine- into lymph (lymphatic system)- emptied into blood 

small intestine adapted- long (time), big SA (villi+microvilli)-1 permeable layer+good b. supply 

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the kidneys- excretion organs

perform 3 main roles 

  • remove urea from blood- produced in liver from excess amino acids 
  • adjust salt + water content in blood- filtering+reabsorbing- end product in urine 

blood gets filtered in nephrons(kidney tubules):

  • 1) ultrafiltration- high pressure- squeezes water, urea, salts, glucose out of blood into capsule
  • membranes between b. vessels in glomerulus+capsule act like fliter- big molecules stay in b.
  • 2)reabsorbtion- all sugar(active transport),sufficient salts(a.t),suffience water(according to ADH)
  • 3)release waste- urea, excess salt+water (nephron-ureter-bladder as urine)

water content controlled by kidneys

  • important keep constant concen. in b. plasma so BP is constant + no osmosis 
  • ADH makes nephrons permeable for water reabsorbtion- brain says release in pituitary gland
  • controlled by negative feedback - water content too low/ too high- mechanism brings back  

urine isnt always same- Heat/exercise- sweat evap. cooling skin (ADH release) , water intake 

dialysis filters blood mechanically- keep right concen. of nutrients+waste removed ,

  • dialysis fluid has same concen of sodium+glucose so arent removed from blood , 
  • partially permeablle barrier- small molecules (waste+excess water) move across in dialysis fluid 
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menstrual cycle

four stages:

  • day 1: uterus lining breaks down 
  • day 4-14: uterus lining builds up (thick spongy layer full of b. vessels- to receive fertilised egg)
  • day 14: ovulation (egg develops+released)
  • day 14-28: wall is maintained- no fertilised egg by day 28- cycle starts again 

contolled by four hormones:

  • FSH(follicle-stimulating hormone)- produced pituitary gland- cause egg develop in one ovary+stim. ovaries to produce oestrogen 
  • Oestrogen- produced in ovaries- causes lining of uterus to repair- stim. LH, inhibits FSH 
  • LH (luteinising hormone)- produced by pituitary gland- stim. ovulation, indirectly stim. progesterone
  • progesterone- produced in ovaries- maintains uterus lining, when level falls lining breaks, inhibits production of LH 

negative feedback mechanisms affect hormone production 

  • concen. of one hormone too high, release of another bring back down 
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controlling fertility

oestrogen used to reduce fertility for contraception:

  • taken everyday keeping level high mimicing pregnancy , inhibits FSH. after while egg development stop + stay stopped 

infertility treatments:

  • Artificial Insemination- mans sperm placed in womans uterus 
  • FSH injections- allows egg to develop+stimulates egg production 
  • In Vitro Fertilisation- womans egg fertilised outside body- need sperm, eggs, health uterus 
  • Ovary Transplants- donated by someone else 


  • IVF not all eggs implanted back- throwing away is denying life 
  • IVF inc. chance of multiple pregnancies- danger to mothers health 

foetuses screened to see if healthy 

  • amniocentesis- needle removes skin cells from fluid surrounding baby + analysed 
  • ethical issues- if has genetic defect makes parents question, inc. risk of miscarriage 
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happens when cells divide- mitosis produces new cells identical to originals  

influenced by many things:

  • diet- children growing need proteins for new cells+minerals for bone growth 
  • exercise- build muscle+bone mass- stim. HGH- pituitary gland stim. long bone growth 
  • hormonal/gentic disorders- giantism- tumour of pituitary gland or dwarfism 

babies growth is monitored 

  • different parts of a baby grow at diff. rates- head grows quickest 
  • babies growth over first few years monitored+plotted by percentiles (2nd-98th)

people living longer than they used to:

  • medical advances, work+housing safer+healthier, people better off can afford good diet, less industrial disease 

problems- population grows: 

  • shortages of housing, pollution, less pensions given out, elderly medical problems inc. tax 
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