gcse science biology unit B5 cards
- 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
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
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
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
heart rate
affected by:
- exercise
- hormones- adrenaline when shock or danger- 'fight or light' response making sure muscles have oxygen
pacemaker
- 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
echcardiogram
- show enlarged heart(heart failure), dec. pumping ability(cardiomyopathy), valve function
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
CHD:
- 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
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
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
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
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
asthma
- 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
digestion
- 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
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
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
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
controversy:
- 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
growth
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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