Presentation on theme: "This is in addition to your revision!"— Presentation transcript:
1 This is in addition to your revision! This is a big topicYou have been warned
2 Microorganisms are Very Small BiggestSmallestBACTERIAVIRUSESFUNGI(On a needle)Colonies of Bacteria and Fungi growing in an agar plate.Agar jelly is their food.When millions of them grow in one place then you can see them
3 Some microorganisms are Pathogenic Pathogenic means they cause diseases If you are infected with one of these you will show symptoms:E.g. runny nose, high temp, spots, sneezing etc.Athletes foot, Thrush FungalSmallpox , Flu ViralTuberculosis, Cholera BacterialSome diseases are caused by the things we do: Over eating, cigarettes, alcohol, drugs These are called LIFESTYLE diseases:Obesity, Heart disease, lung cancer.Remember: YOU can change your lifestyle
4 How do bacteria Grow? Real Fast !!! Just give them: WARMTH – FOOD – WATER (Not O2)1 cell – 2 – 4 – 8 – 16 – 32 – 64 – 128 – 256 – In just 3 HrsAnd it looks like thisGrowth rate = death rate (running out of food or too much excretory products)Getting used to their Petri dish food supplyRapid growthLots of food, water, warmth and spaceMore dying than growingTime
5 Antimicrobials Eg: antibiotics, vaccines, antiseptics Any substance that inhibits (slows or stops) the growth of bacteria, fungi or bacteria,Eg: antibiotics, vaccines, antiseptics
6 So why don’t we get ill all the time So why don’t we get ill all the time? Skin, antiseptic tears, mucus in our nose and windpipe, stomach acid, hairs & earwax all stop them getting in to our body.And if that doesn’t stop them – White Blood Cells from our immune system will:That’s me, the white one
7 Antibiotic Resistant Bacteria – Superbugs – MRSA These are all the exactly the same thing, NASTY bacteria that cannot be killed by AntibioticsWhy are they so common?People take AB’s for colds & flu People don’t finish the courseclick for videoFinal resistant populationIt’s just normal variation, natural selection & mutationsALMOST FORGOT: Antibiotics don’t kill VIRUSES
8 Foreign blood cell being attacked The Immune System‘’ It’s me your friendly neighbourhood white blood cell again. This is how we kill microbes’’1. We find them, surround them and digest them, BURP! (phagocytosis)AND2. Some of us make chemicals called antibodies that stick to microbes. Each microbe has antigens ( molecules on their surface). Antibodies recognise the shape of each different antigen & stick to them. Death followsArghhhForeign blood cell being attacked
9 ‘’OK, but what if I’m too sick and my immune system isn’t stopping them’’? If it’s a bacteria take a course of antibiotics –And don’t stop just because you feel betterAnd you might experience side effects, even death!!And, they might kill all your good microbes.‘’SO WHAT, THE ONLY GOOD MICROBE IS A DEAD MICROBE’’If a fungus is left it will have as much food, space and water as it wants. ‘’And what next’’? GROWTH-- Itch Itch Scratch Scratch --Better get the bio yoghurt out‘’Ahh, that’s better’’And this arrow is NOT pointing at your feet
10 Yeh and I remember you ‘cos I’m a memory cell ‘’I’ve had chickenpox, why can’t I catch it again’’? ‘’Because your now immune to it silly’’ How does that happen?WBC make antibodiesAntibodies attach to nasty microbes & kill themI think I’m dying!Once killed, the WBC’s become MEMORY CELLS which remember the microbes antigens1. First Infection2. If there is a second similar InfectionMe againYeh and I remember you ‘cos I’m a memory cellZap Bang Wallop!The differences between 1 & 2 are:Antibodies are made slowly and you may feel ill before all the MO’s are all killed2. Antibodies are made really fast and you don’t get ill at all. You are IMMUNEI’m dead!
11 This is what an Immune Response looks like Memory cells become activePathogen rapidly destroyedMemory cells created hereAntibody numbersFirst encounter with pathogenSecond encounter with pathogen
12 Vaccines & Vaccinations A vaccination make you immune from a diseaseA vaccine contains either:A dead MO, parts of a MO, or a weakened MOWHY?They ALL contain the MO’s antigens/markersThey all lead to memory cells being madeSome Problem MicrobesFlu Virus – mutates rapidly (changes it’s antigens)HIV virus – Attacks the immune systemand also mutates rapidly…very NASTYMOMONew antigensOriginal antigens
13 Testing DrugsDrugs are tested for safety (side effects) and effectiveness (does it work?)Testing involves 3 stages:On human cells (relatively cheap & quick and may indicate how safe it is)On animals (gives information on safety and effectiveness)On people in a clinical trial (gives info on dosage, side effects)Issues with Drug TestsCan take 10 years to get a new drug to marketVERY expensive: staff & clinical trials, salaries, looking after animals, hospital & lab costs, securityEthical issues with using live animalsEthical issues with testing it on humans,especially if a placebo is involved.Must be approved & licensed by the government
14 Can you describe what's happening in the picture Can you describe what's happening in the picture? When you have written your 5 descriptions, check your answers on the next slide. No peeking!1.3245. what about memory cells?
15 No Peeking until you have completed the first slide 1. Vaccine containing weakened,dead pathogen or parts of it. Each of these has the pathogens antigens (markers). All induce an immune response2. Sometimes there are side effects5. Special White Blood Cells called memory cells are produced so when you come in contact with the real pathogen they REMEMBER IT and produce antibodies SO FAST you don’t get sick; this is immunity.4. Antibodies attach to the pathogen’s antigens (markers). They neutralise the pathogen or attract phagocytotic WB Cells3.White Blood cells produce antigens which match the pathogens antigens (markers)
16 Clinical or Human Trials Increasingly more reliable results(less risk of bias)Open label: Everyone knows who has the drugBlind: Only the doctors know who has the drugDouble Blind: No one knows who has the drug
17 Drug SafetyTaking any drug involves some risk & we all react differently cos we are all genetically differentSide effects can be minor, severe or even cause deathVaccinations have risks too, but the risk to the individual is outweighed by the benefits to the rest of the population.If 95% of the public are vaccinated it stops a disease from spreading and can lead to its eradication (disappearance)Smallpox has been completely eradicated over the whole world
18 Why Do Arteries and Veins Look Different? Arteries carry blood at HIGH pressure, thick walls prevent them bursting, elastic fibres allow them to stretch and go back to their normal shapethin outer wallthick layer of muscle and elastic fibresthick outer layerthin layer of muscle and elastic fibresARTERYVEINVeins carry blood at LOW pressure so only thin walls are needed. They also have valves which prevent blood moving backwardsCapillaries, tiny blood vessels that carry oxygen & food to cells & remove carbon dioxide from cells
19 Running a Clinical Trial Trials have to be designed scientifically to be fair & reliable testsParticipants put in to two groupsParticipants chosen randomly (increases reliability)One group gets the drug the other no drug, (the control group)A control group allows the groups/drugs effect to be comparedIf it’s a totally new drug the control group has a placeboA placebo looks exactly like the real drug but contains no drugPlacebos raise ethical issues; if the new drug may cure a serious disease and does work, people in the control group may die
20 The Circulatory System The heart is made of muscle cells.Every cell needs oxygen and glucose to make energy (respiration)The blood transports oxygen and glucose to every cellBlood leaves the heart under high pressure and returns under low pressureVeins carry blood into the heartArteries carry blood away from the heartCoronary arteries supply heart cells with blood
21 An incubator has to control a babies temperature just like your body ThermostatSet at 37oCTemperature sensorHeaterA typical homeostasis graphThis is the control system sequenceTemperature drops below 37oCSensor detects drop & messages thermostatThermostat messages heater to switch onTemperature rises to 37oCTemperature rises above 37oCSensor detects the rise & messages thermostatThermostat messages heater to switch offTemperature dropsAnd the cycle continues37oC
22 Bad Lifestyle = Increased Risk of a Heart Attack Risk factors: Smoking, lack of exercise, high salt/fat diet & family history2. Build up of fat in artery1. Bad lifestyle3. Blood flow is now reduced to the heart muscle cellsA heart attack animation4. Cells now starved of oxygenheart attack - simple version5. Heart muscle cells begin to die6. Heart attack takes place
23 Water Control Remember Water IN = Water OUT IN: drinks, food, respirationOUT: Urine, faeces, breathing, sweating(exercise is dehydrating)All of these effect the amount of water in the blood plasma and the kidney controls it.
24 Homeostasis & Control Systems Your body needs to keep conditions inside your body the same - otherwise you will feel ill & be illTHIS IS CALLED HOMEOSTASISREMEMBER IT!What needs to be kept under control?Levels of: glucose, water, salt, urea, CO2 & O2-Also: temperature, pH & blood pressureThe underlined ones are in this syllabus
25 Control System Terms/Sequence Stimulus – A factor that changes (e.g. Temp rises)Receptor (sensor) - Detects the changeProcessing Centre – Decides the action to be takenEffector – Produces the responseResponse - The change produced (e.g. Temp drops)Negative Feedback – Part of a control system that reverses changes to bring them back to normal. Allows a quicker response & keeps the value closer to the normal valueYou should be able to recognise these in an incubator and in the kidney/water control system
26 ADH, the Kidney& Water Control StimulusDetected by water receptorsin the processing centre (brain)PituitaryGland Effector (brings about the response)Response:Less pee,blood water increasesMore pee,blood water decreasesGland Effector (brings about the response)Learn all the key words and understand how the flow chart works
27 Drugs and ADH Learn This Alcohol makes people pee a lot of dilute urine by lowering ADH productionThey become dehydratedEcstasy does the oppositeIncreases ADH productionTherefore, stops you peeingSo, ecstasy users should not drink too much water, they will dilute their blood too much and pass out. OR WORSE!!
28 AND Don’t forget to do as many past papers as you can AND Don’t forget to do as many past papers as you can. Check your answers using the mark schemes And if you’re aiming for an A* or B go through each line of the syllabus/specification (find it on the OCR web site) Good Luck
30 Not Yet or not fully covered in this resource Epidemiological Studies (disease causes and their transmission)CorrelationsThe scientific methodRisks and benefits (to individuals and society)EthicsAND FINALLY, THE LAST SLIDE