3Microbes25/03/2017Microbes are micro organisms that can cause diseases. They can enter the body in a number of ways:Microbes (or the poisons they produce) damage cells – these are the symptoms of a disease.They can be breathed in through the mouth or noseThey can enter through cuts or bites in the skin…or other natural openings…
4Disease25/03/2017A disease is any condition where the body isn’t working as it should. This could be caused by a malfunction in the body (as with diabetes) or it could be caused by a type of PATHOGEN (a microbe that causes disease):BacteriaViruses1/1000th mm bigLiving cells (some are harmless)Grow very quicklyAffected by antibioticsExamples: food poisoning, tetanus, sore throats1/1,000,000th mm bigGenetic info inside a protein coatNot affected by antibioticsRelease poisonsExamples: colds, flu, polio, chicken pox
5Bacteria GrowthBacteria can grow and multiply at very quick rates, especially inside the human body.Imagine bacteria could double every 15 minutes. Draw a graph of how many you would have at the following times:TimeNo. of bacteria0 min30 mins1 hr1:302:002:303:003:304:004:305:00141664No of bacteriaTime
6Producing antibodies You’re going down 25/03/2017You’re going downStep 1: The white blood cell “sees” the pathogen (microbe)Step 2: The cell produces antibodies to “fit” the pathogenStep 3: The antibodies fit onto the pathogens and cause them to “clump”Step 4: The pathogens are “eaten” by the white blood cells
7Specific antibodies Microbe Antigen 25/03/2017MicrobeAntigenAntibodies are specific – they will neutralise the microbe they have been made for. They do this by recognising the antigen on the surface of the microbe.Once the body has made the antibody “memory cells” can make it again very quickly if needed, which protects you from catching the disease again.
9Words – antibodies, vaccinated, side effects, epidemic, dead, microbe Vaccinations25/03/2017Vaccinations work by injecting a _____ or weakened form of a ________ into the body. The body is then “tricked” into producing _______. The memory cells then remember the antigen so that, if the person catches the real disease, they are ready for it.In order to prevent an ______, sometimes large numbers of the population can be ______. A possible problem with this is that people can feel ____ ______.Words – antibodies, vaccinated, side effects, epidemic, dead, microbe
10Using Antimicrobials“Antimicrobials” are chemicals used to kill or inhibit microbes. For example:1) Antibacterials kill bacteria but overuse of them can lead to bacteria becoming resistant (e.g. the MRSA “superbug”). This means that antibiotics must be used sparingly. They also have no effect on virii.2) Antifungals can be used to treat fungal infections like Athlete’s foot. Fungi can also become immune over time.
11FungiFungi can also cause unwanted conditions. These conditions can be treated with anti-fungal medicine and antibiotics. Some examples (don’t look if you’re faint hearted!):
12How bacteria become immune 25/03/2017Although vaccinations and antibiotics are useful in the fight against pathogens, bacteria and virii can mutate to form a new, resistant “strain”:Mutation – some strains of bacteria can genetically mutate to develop _______ to the antibiotics.The non-resistant bacteria are _____ by the _______.The resistant bacteria _______ and pass on their mutations to their ______. Don’t use antibiotics unless you need to!!BacteriaNo effect!!PenicillinWords – offspring, resistance, killed, antibiotics, reproduce
14Researching new medicines 25/03/2017Before new drugs can be approved they have to go through three stages. What are the advantages and disadvantages of each stage?1. Is it toxic? Tests are done on cells2. Is it safe for animals? Animal tests are carried out3. Is it safe for humans? Human volunteers are tested on, both with and without the disease.
15Placebos25/03/2017Clinical trials can be done by “open label” (i.e. everyone knows what’s being given to who) or in different ways:1) Blind trialsPatients do not know which drugs they are taking – a real drug or a “placebo”2) Double blind trialNeither the doctors or the patients know if they are taking the real drugPlacebos offer an ethical dilemma as a patient might be sick and still be given a “dummy” pill. Also, you might notice if you had a placebo as you wouldn’t get the side effects of normal drugs...
16An example of drug development - Thalidomide 25/03/2017An example of drug development - ThalidomideMat Fraser, comedian and actorTony Melendez, guitarist
17Developing new drugs25/03/2017Before a new drug can be approved it has to go through a strict testing process. Consider the example of thalidomide:DateEventMid 1950sLate 1950sEarly 1960sMid 1960sAnimal testing using thalidomide was undertaken. Tests showed that it was safe but the tests were “inadequate” – no tests were done on pregnant animalsThalidomide prescribed to pregnant mothers to help sleep and morning sickness problemsBabies are born with birth defects and the drug was banned worldwide. Around 12,000 deformed Thalidomide babies born, 4,000 die in first year.Tests show that Thalidomide can help leprosy sufferers and it is still used today for this purpose.
19“Double Circulation”1) Blood gets pumped from the heart to the lungs and picks up oxygen2) The blood is then taken back to the heart which needs its own blood supply…3) The heart pumps the blood to the intestine (where oxygen and glucose are removed)…5) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and starts again4) … and to the rest of the body (where oxygen is removed)
20The Circulatory system The circulatory system is responsible for pumping ______ around the body. We need blood to be taken around the body because blood contains ________ and _______. These are needed so that all the ____ in our bodies can produce _____ through _________.Blood is pumped at high pressure and measuring the pulse rate can tell us the heart rate.Words – energy, blood, glucose, respiration, oxygen, cells
21Arteries, veins and capillaries Arteries carry high pressure blood away from the heart. They have smaller lumen and no valves.Capillaries have thin walls (one cell thick) to allow glucose and oxygen to pass through. Also used to connect arteries to veins.“Lumen”Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and have valves to prevent backflow of blood.
22Measuring Blood Pressure Blood pressure measurements are taken in terms of “Pressure when heart is contracting over pressure when heart is relaxed”.Healthy blood pressures are defined as being within a range, due to the fact that every person is different.
24Words – alcohol, burst, smoking, heart, fat High Blood PressureHigh blood pressure is a condition where the ______ and blood vessels experience extra strain. It can be caused by:Excess weight or lack of exerciseHigh stress levels_____Excess _______Diets that are high in saturated ___, sugar or saltLong term high blood pressure can cause blood vessels to weaken or even ______ and can lead to heart disease.Words – alcohol, burst, smoking, heart, fat
25Heart Disease and Lifestyle Who is the most likely to die of heart disease in the next 20 years?
26Words – smoking, exercise, genetic, saturated Heart Disease RisksClearly, the risk of heart disease depends on a number of factors:Lack of _________Eating foods high in _________ fats______ factors, e.g. if your parents had itWhether or not you _______Factors that affect the risk of heart disease can be identified via large-scale genetic studies.Words – smoking, exercise, genetic, saturated
28Cannabis: Pros and cons 25/03/2017In January 2004 cannabis was changed from a class B drug to a class C drug. Some people think that Cannabis should be made legal. What are the pros and cons of cannabis?Pros:Cons:
29Drugs Research Project 25/03/2017Explain and give examples for the following:Why do people use illegal drugs?What are the drawbacks of illegal drugs? What can they cause?Choose one drug and discuss how it affects the human body
31HomeostasisHomeostasis means “controlling internal conditions” and it is achieved using the body’s nervous and hormonal systems. Some examples of things that need to stay constant:Body temperatureAmount of sugar in the bodyAmount of water in the bodyThe body does all these things so that its cells can continue to work normally. Let’s look at temperature and water content in more detail…
33Body Temperature Receptors in the skin detect the external temperature Temperature detectors in the brain detect the blood temperatureThe brain coordinates a response using hormonesEffectors (muscles and sweat glands) carry out the responseReceptor – Processing Centre - Effector
34Controlling Water Content Low blood water level causes a high salt concentration“Negative Feedback”Receptors in the hypothalamus detect the high salt contentMore ADH is secreted into the blood by the pituitary glandThe kidney becomes more permeable to water so more is absorbed.The bladder fills with a small quantity of urineNormal blood water level is achieved.
35Controlling Water Content 2 High blood water level causes a low salt concentration“Negative Feedback”Receptors in the hypothalamus detect the low salt contentLess ADH is secreted into the blood by the pituitary glandThe kidney becomes less permeable to water so more is absorbed.The bladder fills with a large quantity of urineNormal blood water level is achieved.
36Controlling Water Levels Our bodies control water content using a “____ ______” mechanism. Controlling water content is important as many process that occur in _____ need the correct water content in each cell.Factors affecting water content of our bodies:External temperature – e.g. is the person _______?Intake of _______ and foodHow much is lost through breathing and _______Alcohol – this can suppress ADH which leads to __________ due to the body producing more urineDrugs, e.g. Ecstasy, which causes increased ____ production.Words – ADH, negative feedback, water, sweating, dehydration, cells, urine