Year 9 Science Notes PDF

6Unit 1- Immune System: Stile Glossary Name Definition Bacteria bacterium (plural: bacteria) A simple, single-celled microbe without a nucleus Fungi...

6Unit 1- Immune System: Stile Glossary Name Definition Bacteria bacterium (plural: bacteria) A simple, single-celled microbe without a nucleus Fungi fungus (plural: fungi) An organism with complex cells that feeds off a living host microbes Microbes are the most abundant and diverse living things on Earth. They live in almost every environment on the planet, from ice caps and deserts to the ocean depths. Microbes are microscopic organisms ( seen only by a microscope and not by the naked eye ), which include bacteria, viruses, fungi and protozoa. Immune system immune system The body system that prevents and fights disease immunity immunity  The body's ability to protect itself from infection disease Any medical condition with specific symptoms pathogens Microbes and other microscopic agents that cause disease infectious diseases. Diseases that are caused by pathogens infection. When pathogens manage to enter the body and multiply non-infectious diseases Pathogens do not cause many diseases, but by lifestyle, environmental factors and inherited genetic factors. Pathogenic pathogenic Causing disease frequency frequency The number of waves that go by in one second. pseudoscience pseudoscience A claim that is presented as scientific but doesn't follow the scientific method cell cell The smallest unit of life B cell The third line of defence is made of specialised white blood cells called B cells. Clones Once an antibody finds its perfect match, it triggers the B cell to clone itself. memory cell memory cell A B cell that remains in the bloodstream to recognise pathogens White blood cell white blood cell A blood component that helps protect the body from infection virus virus A microscopic infectious agent made of genetic material and proteins contagious when an infectious disease can pass from one person to another coronavirus coronavirus A type of virus that can cause diseases in mammals and birds, including COVID and the common cold Non-contagious. A medical condition that cannot spread from person to person faeces faeces Solid waste that remains after food is digested epidemic The rapid spread of a disease in a specific  community or region endemic The continual presence of a disease in a specific community or region pandemic The rapid spread of a disease across multiple regions worldwide first line of defence The system of barriers to prevent pathogens from entering the body is the and can both be classified into chemical and physical barriers. ​ Physical barriers stop pathogens from entering the body by blocking or trapping them. Examples include skin and mucus. Some physical barriers, like cilia, actively push pathogens out. This is shown in the diagram. ​ Chemical barriers kill pathogens before they can enter the body. They include stomach acid as well as enzymes in tears, saliva and mucus. cilia cilia Microscopic hairs on cells that line the airways enzyme enzyme A substance that can speed up a chemical reaction, such as chemical digestion in the body second line of defence general responses to infection membrane membrane A thin layer that forms a barrier phagocyte phagocyte A white blood cell that engulfs and destroys pathogens bacterium (plural: bacteria) bacterium (plural: bacteria)  A simple, single-celled microbe without a nucleus An increase in core temperature above 38 fever degrees. Stomach acid And the acid in your stomach kills many pathogens negative feedback loop one change in a system causes another change in the opposite direction A painful redness or swelling of part of the inflammation body When injured cells release chemicals that Core temperature signal the brain to raise the temperature of the internal organs A protein that can identify and fight a antibody specific pathogen polio polio An infectious disease caused by a virus that mainly affects the nervous system and can  cause loss of movement vaccination vaccination A treatment that helps build immunity to an infectious disease paralysis paralysis The inability to move parts of the body —---------------------------------------------------------------------------------------------------------------------------- Unit 1- Pathogens Learning Intention: -​ Explain the difference between microbes and pathogens -​ Compare different types of pathogens Key Words For Definitions: -​ Microbes -​ Disease -​ Pathogens Microbes: Microbes are the most abundant and diverse living things on Earth. They live in almost every environment on the planet, from ice caps and deserts to the ocean depths.  ​ Microbes are microscopic organisms ( seen only by a microscope and not by the naked eye ), which include bacteria, viruses, fungi, protozoa and Algae. ​ They are ubiquitous, meaning they can be found in virtually every environment, including on human skin. ​ Some microbes prefer to live on or inside larger organisms - including us. ​ Microbes in our bodies make up around 2kg of our weight. ​ Not all microbes are harmful, some benefit us, for example, microbes help us to digest the food we eat. ​ Microscopic agents are microbes that come in different shapes and sizes.s Pathogens: ​ Any medical condition with specific symptoms is called a disease. A person has a disease only when symptoms appear. ​ Pathogens are microbes that cause diseases. ​ All pathogens have different types of shapes and structures. (An example of a pathogen is E. coli, which is a type of bacteria. E. coli can cause food poisoning, leading to symptoms such as stomach cramps, diarrhea, and fever.) ​ Diseases caused by pathogens are known as infectious diseases. ​ Some examples of infectious diseases include food poisoning, the common cold, measles, and COVID-19. Types of Pathogens:​ Bacteria:​ Viruses:​ Fungi: Types Of Pathogens Bacteria Viruses Fungi Example Salmonella, a cause of Influenza virus; Micrsoproum, cause  food poisoning caused by the flu of athlete's foot Unicellular or unicellular Neither ( non-living ) Unicellular or multicellular multicellular Cells Small, simple cells Not cells ( genetic Complex cells but without a nucules material in a layer of can’t protein and fat photosynthesise Cause disease by Attacking cells and Entering cells to Feeding of the host; taking their reproduce, causing some produce toxins nutrients; some them to burst and die produce toxins * Viruses are not considered microbes by many scientists, but they still could be pathogens.* -​ Viruses are not considered living organisms because they lack the ability to reproduce independently or carry out metabolic processes. They consist of genetic material enclosed in a protein coat and require a host cell to replicate. While they are not microbes, viruses can still cause disease in their host organisms by hijacking the host's cellular machinery to replicate/re-produce themselves, often leading to cell damage or death. This makes them pathogens, even though they are not considered living organisms. —-------------------------------------------------------------------------------------------------------------- Unit 1- Infectious Disease Learning Intentions: -​ Explain whether a disease is infectious or Non-infectious -​ Identify how infectious diseases can spread from person to person Keywords to define: -​ Non-contagious -​ Non-infectious disease -​ Infectious disease Infectious and Disease Infectious: -​ when pathogens manage to enter the body and multiply -​ The pathogens can damage the body’s cells, causing symptoms such as rash or fever. -​ Many infectious diseases can spread from person to person. E.g. - Cold, flu and hepatitis but not all infectious diseases are contagious. E.g. -the yellow fever virus passes from mosquitoes to people. But it can’t spread from person to person. Disease:​ - different pathogens cause different diseases with typical symptoms. E.g. - the measles virus typically causes coughing, fever and a rash The spread of infectious diseases: -​ Pathogens can pass from person to person in different ways For example ​ Shaking hands ​ Sharking drinks ​ Breathing salvia droplets when an infected person coughs or sneezes ​ If you are directly exposed to an infected faeces or vomit ​ Touch a contaminated surface and then touch your mouth and nose Comparing infectious diseases: You compare infectious diseases by looking at the: -​ Deadliness of the disease ( the percentage of infected people that die from it ) -​ The contagiousness of a disease ( how easily it spreads through a population ) The contagiousness of a disease is measured by the average number of people that an infected person passes the disease to. This assumes that no one is protected by vaccination or previous exposure to the disease. Non- Infectious diseases: -​ Diseases not caused by pathogens are non-infectious diseases -​ Non-infectious diseases cannot spread from person to person through a community -​ Since Non- infectious are not caused by pathogens instead they might be caused by: ​ Lifestyle factors, such as smoking  ​ Environmental factors, such as air pollution ​ Genetic factors inherited from one’s parents Some diseases that are not infectious: ​ Diabetes ​ Asthma ​ Cancer Classifying outbreaks Epidemic - The rapid spread of a disease in a specific community or region Pandemic - the rapid spread of a disease across multiple regions or worldwide Endemic - the continual presence of a disease in a specific community or region —-------------------------------------------------------------------------------------------------------------- Unit 1- The first line of defence Learning Intentions: -​ Describe the role of the immune system -​ Explain how the first line of defence prevents entry of pathogens Keywords to define: -​ Membrane The immune system: The immune system is a system in our bodies that prevents diseases. The immune system is made up of many organs, tissues and cells working together. The immune system fights infectious and non-infectious diseases. The immune system can be described as having three lines of defence to protect the body against pathogens. The first defence is made up of barriers to prevent infection. The second line of defence is made up of responses to infection that apply generally to all pathogens. The third line of defence provides immunity against specific pathogens. The first line of defence: The first line of defence is when there are barriers to prevent pathogens from entering the body Pathogens must take it past the first line of defence before they can cause an infection First line of defence: The first defence is made up of barriers to prevent infection. -​ Skin: acts as an effective barrier against most pathogens - unless it’s broken by a cut or graze -​ Tears, salvia and mucus: tra[ pathogens so they can be flushed from the body or swallowed The barriers to preventing infection in the first line of defence: -​ Skin: acts as an effective barrier against most pathogens- unless it’s broken by a cut or graze -​ Tears, Salvia and mucus: trap pathogens so they can be flushed from the body or swallowed. These bodily fluids also contain chemicals called enzymes. They can kill many types of bacteria by breaking down their cell walls. -​ Stomach acid: not only aids digestion but also kills many of the pathogens we swallow before they can cause an infection -​ Cilia: are microscopic hairs on the cells that line the airways. Cilia move back and forth, pushing mucus and trapped pathogens out of the airways. -​ Urine flow: flushes pathogens out of the bladder and urethra. The barriers that make up the first line of defence are classified as either physical or chemical. -​ Physical barriers: stop the pathogens from entering the body by blocking or trapping them. Examples include skin and mucus. Some physical barriers, like cilia, actively push pathogens out. -​ Chemical barriers: kill pathogens before they can enter the body. They include stomach acid as well as enzymes in tears, saliva and mucus. —-------------------------------------------------------------------------------------------------------------- Unit 1- The second line of defence Learning Intentions: -​ Explain how the second line of defence responds to an infection -​ Compare the first and second lines of defence  -​ Explain why a negative feedback loop is important for controlling a fever. Keywords to define: -​ Phagocytes The second line of defence: When an infection occurs because pathogens make it past the first line of defence and enter the body, the immune system responds in some general ways that treat all pathogens equally. For example, the immune system can increase the core body temperature to produce a fever. This can help fight a range of different pathogens by making it too hot for them to survive. Such general responses to infection make up the second line of defence. The second line of defence: General responses to infection -​ Fever: is an increase in core body temperature above 38C. It is usually accompanied by shivering and sweating. A high temperature slows down or even kills some pathogens. It also speeds up processes that help the immune system deal with the threat. -​ Inflammation: painful readiness swelling around the site of an infection is called inflammation. It happens because more blood is directed to that part of the body. Blood contains white blood cells that are specialised to fight off pathogens. -​ Phagocytes: some white blood cells destroy anything they don’t recognise as part of the body. They do this by ‘swallowing’ or ‘engulfing’ it. These blood cells are called phagocytes. Phagocytes help to protect the body by engulfing and destroying pathogens. ​ While fighting an infection, it’s normal for white blood cells to die. Pus: when dead white blood cells build up at the site of a wound, they form pus. Snot: snot turns yellow when it contains large numbers of dead white blood cells. This is a sign that the body is fighting a respiratory infection. ​ How the second line of defence relies on pumping blood around the body. The second line of defence in our immune system relies on the heart's ability to circulate blood throughout the body. This circulation is important because it transports white blood cells, which are necessary for fighting off invaders like bacteria and viruses. When pathogens enter the body, the immune system produces more white blood cells. The heart then pumps these white blood cells through the bloodstream to the infected areas, allowing them to attack and destroy the invaders, preventing them from spreading and causing illness. Comparing the first and second lines of defence: Arranging terms to complete the summary of the first and second line of defence: The first line and second lines of defence are general ways that the body protects itself from pathogens. The first line consists of barriers, like mucus and skin. Its role is to prevent infection. The second line includes fever and inflammation. They are the immune system’s general responses after a pathogen has entered the body. Identifying the similarities and differences between the first and second lines of defences: Similarities: -​ Both the first and second lines of defence are general features or responses that defend against any type of pathogens -​ The first and second lines of defences are part of the immune system to protect the body against pathogens. -​ Both systems have more than one way to work Differences: -​ The first line of defence is to prevent infections while the second line of defence is a general response to an infection -​ The first line of defence has barriers, like, skin, sweat and tears, while the second line of defence has phagocytes and responses such as inflammation and fever -​ The second line of defence fights pathogens once they are inside your body. Examining Fever: -​ During an infection, pathogens damage cells in the body -​ The damaged cells release chemicals that signal the brain to raise the temperature of the internal organs, also called core body temperature. This produces a fever that helps fight the pathogens by slowing or killing them.  -​ When the brain receives signals to change the core body temperature, it triggers reactions like shivering and sweating. -​ As the body recovers from the infection, cells stop releasing the signalling chemicals., the core body temperature then returns to normal. shivering sweating Effects on core body shivering helps to increase cooling decreases our temperature our temperature due to the temperature due to the movement helping the body sweating, making us not to warm up move resulting in our cooling How it works The pathogens enter our when we are sweating, it means we are overcoming the body, which then produces pathogens because the white the fever that helps fight the blood cells have done their job by killing and there are pathogens by slowing or no pathogens left. killing them. As the body  recovers from the infection, cells stop releasing the signalling chemicals. Our body knows when to shiver through what is known as a negative feedback loop, this happens when one change in a system causes another change in the opposite direction. The role of negative feedback: -​ When the body is healthy, its core body temperature needs to be kept within narrow limits. Usually, this is about 37C. -​ If the temperature gets too high or low, natural mechanisms work to return it to normal. -​ So one change in a system causes another change in the opposite direction. This is called a negative feedback loop. -​ During a fever, the body resets its target to a higher temperature to help fight the infection. -​ However negative feedback loops still work to keep the temperature within narrow limits. If the body heated up too much, this would cause organ damage or even death -​ A negative feedback loop is important for controlling a fever because when we still have pathogens inside our bodies our temperature rises, but if our temperature rises to a dangerous point of level it can cause death, which is why a negative feedback loop is important.  -​ Why negative feedback loops are also needed to control inflammation: Negative feedback loops are essential for controlling inflammation because they act like a brake on the inflammatory response. When inflammation starts, it triggers the release of chemicals that signal the body to keep fighting. However, as the inflammation starts to do its job, it also triggers a stop signal. This signal tells the body to calm down and reduce the inflammation. This feedback loop prevents inflammation from becoming excessive and causing more damage than good like death. -​ —-------------------------------------------------------------------------------------------------------------- Unit 1- The third line of defence Learning Intentions: -​ Explain how the third line of defence fights pathogens -​ Explain why the third line of defence is needed for immunity to a disease Keywords to define: -​ B cells  -​ antibody The third line of defence: Immunity against specific pathogens -​ The second line of defence responds quickly but in a general way. The immune system has another way of fighting infections that targets specific pathogens. These specialised weapons make up the third line of defence. It has two main roles: ​ Identify and destroy specific pathogens ​ Build long-lasting immunity against the pathogens in case they infect the body again. -​ The third line of defence is made up of specialised white blood cells. There are thousands of types of pathogens and each type is unique. For example, the influenza virus has a different shape and structure compared to the Ebola virus. ​ The first two lines of defence respond in a general way that treats all pathogens equally. ​ The third line of defence targets the specific pathogen that has invaded the body. -​ A strength of the third line of defence is that it can develop an effective weapon against a particular pathogen. -​ It can also remember that pathogen if it ever shows up in the body again. It can then use the same weapons to defeat it more quickly. -​ The third line of defence adapts to any new threat and remembers it for the future. How does the third line of defence work? -​ The first time your body encounters a pathogen, it takes a few days for the third line of defence to mount an attack. During this time you will feel sick. -​ The third line of defence takes time because it needs to identify the pathogen first. To do this, it relies on specialised white blood cells called B cells. Identifying pathogens: B cells travel the bloodstream on the lookout for pathogens. B cells produce special proteins called antibodies, which it carries on its cell membrane. -​ Antibodies bind onto markers on pathogens to identify them. Each type of pathogen has unique markers. This means they can only bind to antibodies with a matching shape- similar to a lock and key. Fighting pathogens: Once an antibody binds to a pathogen, the B cell releases millions of matching antibodies into the blood to fight the pathogen. -​ The B cells also clone itself to form an army. That releases a barrage of antibodies to fight and neutralise the pathogen. Becoming Immune:​ After the infection has been defeated, some of the B cells remain in the blood as memory cells along with any leftover antibodies. Together, these form your immune system’s memory of the pathogen. -​ If you’re infected by the same pathogen again, the third line of defence will respond faster and stronger than it did the first time. It works so fast that you don’t even get sick. -​ This is what it means to become immune to the disease. Arranging the descriptions to summarise how the third line of defence builds immunity against a pathogen. B -cells: The third line of defence made up of specialised white blood cells called B cells Antibodies/Pathogen: B cells have proteins called antibodies on their surfaces. Antibodies bind to pathogens to identify them. Each type of pathogen has unique surface markers. Only antibodies with matching shape can bing to them. Clones: Once an antibody finds its match, it triggers the B cell to clone itself. The new cell army produces millions of antibodies to fight the pathogen. Memory cells: After the pathogen is defeated, antibodies and memory cells remain in the body. This provides immunity if the pathogen eve appears again. ​ Why does the third line of defence take more time to respond to an infection than the first and second lines of defence?: The third line of defence needs time to identify pathogens and produce weapons ( antibodies ). This is because it needs time to find the pathogen's unique markers. While the first and second lines of defence are a general response. ​ Why you can’t become immune to a pathogen that has only encountered the first two lines of defence: You can't become immune to a pathogen that only encounters the first two lines of defence because your immune system hasn't been activated yet. While these first two lines can keep out many invaders, they don't learn how to fight them. The immune system needs to see the pathogen and learn how to defeat it. Only then can you develop immunity and prevent future infections from the same pathogen ​ The number of antibodies starts to decrease after the body has overcome the pathogens resulting in a lower amount of pathogens produced. The effect of measles on immunity: In 2019, two scientific studies reported a surprising side effect of getting measles. It can cause the immune system to "forget" how to fight pathogens that cause other diseases. why "immune amnesia" caused by measles can have long-term health consequences: Immune amnesia caused by measles can have long-term health consequences because without antibodies you will be more open to different types of infections resulting in you being in danger of getting infections making you lose antibodies that have been built up, and due to the antibodies fighting different infections at the same time it takes longer time to respond to illnesses and sometimes those innless can be severed later in life if you haven't beaten them when you are younger. —-------------------------------------------------------------------------------------------------------------- Unit 1- Vaccinations Learning Intentions: -​ Explain why vaccines build immunity against specific diseases -​ Evaluate claims made against vaccines The keyword to define: -​ Vaccination Vaccination: -​ Treatment that helps the body build immunity to an infectious disease is called a vaccination -​ How do vaccinations work: -​ Most vaccinations are given by mouth as a nasal spray and injections Vaccination works by introducing a dead or weakened pathogen into the body. ( A substance that boosts the body’s immunity to a specific pathogen is called a vaccine. This allows the immune system to identify the pathogen and develop weapons to figt it. The weakened form of the pathogen can’t multiply or cause disease.  -​ Vaccination relies on the immune system’s third line of defence. When a vaccine introduces a new pathogen:​ 1. B cells with matching antibodies bind unique markers on the surface of the pathogen. -​ 2. After binding, B cells produce antibodies and memory cells. These remain in the body as a “memory” of the pathogen. The antibodies and memory cells are weapons that target the pathogen. This means that the immune system is prepared to attack if the pathogen ever shows up again. So vaccination helps the body build immunity in the same way as if it were infected – but without the symptoms of disease. Summarisation of how vaccines work:​ A vaccine is a substance that contains dead or weakened pathogens. A vaccine triggers B cells to produce antibodies and memory cells that remain in the body. They allow the immune system to quickly identify and fight the pathogen in any future infection. In this way, vaccination helps the body build immunity to an infectious disease. Comparison of being infected by a pathogen and being vaccinated against a pathogen. Similarities: -​ They both involve a pathogen entering the body. -​ Trigger an immune response -​ Antibodies are produced to fight infections Differences: -​ The weakened form of the pathogen can’t multiply or cause disease. -​ Vaccination works by introducing a dead or weakened pathogen into the body -​ Being infected by the pathogens is likely to cause symptoms while a vaccination does not cause symptoms.  ​ Using your knowledge of the third line of defence, explain why a different vaccine needs to be developed for each infectious disease: -​ Not all viruses or pathogens are the same -​ All pathogens are different and unique -​ Different pathogens need different antibodies that are going to lock like a key -​ Each antibody can bind to one pathogen 2 Myths of vaccines: 1.​ Vaccines have a high risk of dangerous side effects 2.​ Vaccines cause Autism —-------------------------------------------------------------------------------------------------------------- Unit 1- Herd Immunity- Part 1 Learning Intentions: -​ Explain how herd immunity protects vulnerable people Key words definition:​ - Vaccination rate Infection rate How vaccination protects vulnerable people: -​ Getting vaccinated protects you by boosting your immunity to an infectious disease. But it also helps protect your entire community. -​ When enough people are vaccinated, the disease can't spread. This protects vulnerable people who can't be vaccinated. The protection they get from their community is called herd immunity. -​ When enough people are vaccinated against a disease, it can’t spread through a population. This is called herd immunity. In this way, vulnerable people with weaker  immune systems are also protected. This includes babies, the elderly and people with cancer. Highly vulnerable locations: -​ A childcare centre -​ A retirement community/ home -​ A hospital The locations above are highly vulnerable. I have chosen a childcare centre because people's kids in childcare may be too young to get vaccinated because of their weaker immune systems due to not being fully developed. I have chosen a retirement home also because the older people have weaker immunity and lastly I have chosen a hospital because people in the hospital are already getting treatment and they too may have a weak immunity. The importance of vaccination rates:​ The percentage of unvaccinated people who end up being infected is called the infection rate. -​ Even if a disease doesn't exist in your community, it can be brought in by a traveller. When this happens, the spread of the disease depends on the population's vaccination rate -​ When the vaccination rate is high enough, a disease can't spread through the community. Not many people are infected and the infection rate is close to zero. Herd immunity protects those who are vulnerable. -​ When the vaccination rate is too low, an outbreak can spread. Those who are not vaccinated are at risk of being infected. In this case, there is no herd immunity to protect vulnerable people. The relationship between vaccination rate and infection rate: Based on the calculations on the model above provided, the relationship between the vaccination rate and infection rate is that the lower the vaccination rate is the higher the infection rate is. how other members of the community are affected by the decision of not to get vaccinated, using the concept of herd immunity: The members of the community are affected by the decisions the parents have made because the parent's decision not to vaccinate their child affects more than just their own family. When a large portion of the community is vaccinated, it creates a barrier against the spread of disease, which is herd immunity. This barrier protects everyone, including those who can't be vaccinated due to age or health conditions. However, when people choose not to vaccinate, they create gaps in this protective barrier, making it easier for the virus to spread and maybe harm others. So a decision not to vaccinate can have effects that extend beyond the individual family. —-------------------------------------------------------------------------------------------------------------- Unit 1- Herd Immunity - Part 2 Learning Intentions: -​ Analyse how herd immunity depends on the vaccination rate Simulation: Vaccination rates and herd immunity: In the graph shown above, we can see that in all 3 types of diseases, their infection rate declines as the vaccination rate starts to increase. We see that the two types of diseases, which are Ebola and Polio infection rate decrease when the vaccination rate reaches around 50 per cent, while the disease Measles declines late on when the vaccination rate reaches around 60 per cent. Describe the general relationship between the vaccination rate and infection rate shown in your graph: In the graph shown above, we can see that in all 3 types of diseases, their infection rate declines as the vaccination rate starts to increase. We see that the two types of diseases, which are Ebola and Polio infection rate decrease when the vaccination rate reaches around 50 per cent, while the disease Measles declines late on when the vaccination rate reaches around 60 per cent. your results to recommend a vaccination rate that will provide herd immunity: A recommendation of a vaccination rate that will provide a heard community, will be 75 per cent for the two diseases Ebola and Polio and 85 per cent for the disease Measles. All three diseases will not provide a herd community because they are different, with different severities, how easily they can be transferred through people which is known as the infectious rate. Propose why a new disease is more likely to spread quickly: A new disease is more likely to spread quickly because the scientists take time to find out the medicine/treatment but also since there are vulnerable like the elderly, babies and people with different infections, it will be more likely to spread faster, especially with the newborn/infants rate rising.