Health Lifestyle and Infection Past Paper 2024 PDF

Recap  Five different groups of pathogens Recap  Example of a disease caused by protozoa. Recap  Example of one physical barrier in your body to stop you being infected by a pathogen Recap  Example of one chemical barrier in your body to stop you being infected by a pathog...

Recap  Five different groups of pathogens Recap  Example of a disease caused by protozoa. Recap  Example of one physical barrier in your body to stop you being infected by a pathogen Recap  Example of one chemical barrier in your body to stop you being infected by a pathogen Recap  One type of behaviour you can follow to reduce your chance of becoming infected by a pathogen Health, lifestyle, and infection Lesson 1: Diseases you can catch: Pathogens Lesson 2: How the body defends itself Lesson 3: Vaccines and antibiotics Lesson 4: Diseases you don’t catch Lesson 5: Lifestyle and risk factors Lesson 6: Drugs Lesson 7: Buffer Lesson 8: Test If it’s in purple, find it and fill in the gaps. Learning goals  Be able to describe the process of inflammation.  Be able to explain the role of phagocytes in fighting infection.  Understand how T cells and B cells fight infection in the body. Preventing infection  In the last lesson we talked about how to avoid getting infected by pathogen, both how your body stops pathogens from entering your body and what you can do to stop them entering your body. Preventing infection  But let’s say you do eventually get infected?  What happens? The immune system  The part of your body that is infected sounds an alarm letting the immune system know that pathogens have entered the body. The immune system  It does this by releasing chemicals. The immune system  When your body gets infected by pathogens, it releases chemicals to alert the immune system. The immune system  So the alarm has sounded, what responds to it? The circulatory system – blood The circulatory system – blood  Four components of blood?  What does each component do? The circulatory system – blood The circulatory system – blood Component Description Plasma Made up of water, sugar, salts and nutrients and waste substances. About 50% of the volume of blood. Red blood cells A type of cell that can carry oxygen and transport it in the body (and helps the blood carry carbon dioxide) White blood cells Cells which can fight infection in the body Platelets Your body’s own plasters. They clump together to form scabs when you get cut. This process is The circulatory system – blood  The chemicals that are released where the infection is happening, create large gaps in capillaries that allow white blood cells to reach the pathogen. The immune system  This increase in blood flow can lead to the area of infection become swollen and red.  This process is called inflammation. The immune system  In some people inflammation can be triggered by harmless things. The immune system  And the body can sometimes see our own cells as pathogens by mistake. The immune system  White blood cells come in many different types White blood cells  The way the different white blood cells work together to fight infection is hugely complicated.  It’s an area of Biology/Medicine in its own right (Pathology and Immunology)  We don’t really completely understand all of it yet. White blood cells  We’re going to look at three different types of white blood cells. Phagocytes  The first responders to infection are phagocytes. (äterceller)  They wrap around anything that looks like a pathogen and then dissolve it. White blood cells The circulatory system – blood The circulatory system – blood The circulatory system – blood  Like any good battle, there are casualties on both sides and dead pathogens and dead phagocytes can gather together to form pus.  (particularly when the pathogen is a bacteria) The immune system  Phagocytes (äterceller) are a type of white blood cell involved in fighting infection.  Phagocytes are not specific. They eat up anything that looks like a pathogen.  Dead phagocytes and pathogens often form pus. The circulatory system – blood  Phagocytes are very much like the front line soldiers in the battle against infection. They target anything that looks like an enemy.  They make up the majority of white blood cells. The circulatory system – blood  They are the first white blood cells to fight any infection in the body. The circulatory system – blood  But if they can’t clear the infection, the “Special forces” need calling in. The circulatory system – blood  These “Special forces” use different tactics to fight infection. The circulatory system – blood  These “Special forces” white blood cells are called T cells and B cells. The circulatory system – blood  While phagocytes attack anything that looks like a pathogen, T cells and B cells seek and destroy the particular type of pathogen that’s entered the body.  They are like contract killers. The Immune system  Every cell in our body, and every cell of every living organism (including virus particles) has little id-tags sticking out of the outside of it.  These id tags are unique to each cell and are called antigens. The Immune system  An antigen is like an ID tag which sticks out of all cells.  Different pathogens have different antigens. The circulatory system – blood  T Cells and B Cells are special types of white blood cells that hunt down pathogens based on their antigens. The circulatory system – blood  T Cells can kill pathogens on their own or they can also tell other white blood cells to come and join the fight. The Immune system  B Cell produce a special weapon against pathogens called antibodies. The Immune system  Antibodies kill and help other cells kill pathogens.  Different B Cells produce different antibodies. The Immune system  Only the right type of antibody works against a pathogen. The Immune system  B Cells produce a special weapon against pathogens called antibodies which kill pathogens.  One particular antibody only works on one particular pathogen. The Immune system  The are billions of B Cells and T Cells in our body.  But they are all slightly different. Each B Cell and T Cell can defeat only one type of pathogen. The Immune system I attack flu I attack strain 1 COVID strain 1 I attack I attack flu COVID strain 2 strain 2 I attack the common cold strain 2 I attack the common cold strain I attack 1 norovirus strain 2 The Immune system I attack pathogen 235526291 2 I attack pathogen 654321765 12 Antigen id: 956315756321 I attack pathogen 956315756 321 The Immune system I attack pathogen 235526291 2 I attack pathogen 654321765 12 Antigen id: 956315756321 I attack The antibodies produced by pathogen 956315756 this B Cell can attack COVID. 321 But not the other two, because they’re not programmed to attack COVID. T Cells and B Cells  The body has billions of T cells and B cells and they are all slightly different.  EachT and B cell can only fight one type of pathogen. The Immune system I attack pathogen 235526291 2 I attack pathogen 654321765 12 Antigen id: 956315756321 I attack pathogen There are billions of B 956315756 321 and T Cells in our body, but only a very small number of them produce the right The Immune system I attack pathogen 956315756 321 I attack pathogen 956315756 321 The Immune system THERE ARE TOO MANY THERE ARE TOO MANY T Cells and B Cells  When we are infected by a new pathogen, the body may only have a very small number of T cells and B cells that can fight that particular pathogen.  There aren’t enough to fight the infection. T Cells and B Cells  In order to defeat a quickly multiplying pathogen, your body needs to clone its T cells and B cells. T and B Cells  Eventually your body makes a clone army of T Cells and B Cells for one particular pathogen.  T and B Cells  The body can go from having single figure numbers of specific T and B cells to millions or billions. T and B Cells  Butthis cloning process takes a long time. (often between 7 and 14 days) And before this happens, the pathogen is often winning. T and B Cells  Anddepending on the pathogen, this can sometimes be extremely serious.  Infectionby some pathogens can cause life-threatening conditions. T and B Cells  Inorder to fight infection, the body clones the correct T and B cells (make copies of them).  This cloning process can take a long time.  Duringthis time, we can sometimes become very ill as the pathogen keeps copying itself. T and B Cells  Sothe body makes the clone army of T Cells and B Cells and they wipe out the pathogen. T and B Cells  Often when you’ve been infected by one type of pathogen you don’t tend to get ill from it again. T and B Cells  We say that you’re immune to the disease. T and B Cells  Butthat doesn’t mean that you can’t be infected. In fact you often can be. T and B Cells  Butthe difference the second time around is that you’ve now already got loads of cloned T cells and B Cells ready and waiting to fight this pathogen. T and B Cells  When pathogen infects you the 2nd time, it doesn’t stand a chance. It’s nearly always eliminated before it can do any real damage. Immunity FIRST INFECTION FOLLOWING INFECTIONS Large number of Low number (< 100) of specific T and B specific T and B cells cells able to fight the able to fight the pathogen in the body pathogen in the Body clones T body Body clones T and B cells Takes to millions and B cells to time and millions and billions billions level. T and B cells level. T and B cells destroy all pathogens destroy all and defeat pathogens and infection defeat infection Immunity FIRST INFECTION FOLLOWING INFECTIONS Large number of Low number (< 100) of specific T and B specific T and B cells cells able to fight the able to fight the pathogen in the body pathogen in the Body clones T body Body clones T and B cells Takes to millions and B cells to time and millions and billions billions level. T and B cells level. T and B cells destroy all pathogens destroy all and defeat pathogens and infection defeat infection Lymphocytes  When the body has fought off the infection, there are now many more T cells and B cells that can fight against pathogens with that particular antigen.  If you get infected by the same pathogen again your body is ready to fight the infection immediately.  It’s as though your body has remembered the pathogen. This is called immunity and is why we rarely get sick the second time we get the same infection. Learning goals  Be able to describe the process of inflammation.  Be able to explain the role of phagocytes in fighting infection.  Understand how T cells and B cells fight infection in the body.