Immunology - An Introduction to Pathogens PDF

The Immune System Learning Outcomes To understand the key characteristics of microorganisms To describe the main types of pathogens and explain the diseases which they are responsible for causing To understand vectors of transmission and how disease can spread among populations Why do...

The Immune System Learning Outcomes To understand the key characteristics of microorganisms To describe the main types of pathogens and explain the diseases which they are responsible for causing To understand vectors of transmission and how disease can spread among populations Why do we get ill? Pathogens invade our body and cause dysfunction within our homeostasis  Pathogens cause disease Research Task: What are the top 5 communicable diseases in the world? Pathogenic* – A medical term that describes any microorganism that can cause disease Pathogens Can you name the major types of pathogens? 1.Bacteria 2.Virus 3.Fungi 4.Protists An introduction to Bacteria https://www.youtube.com/watch?v=ORB866QSGv8  Task – The structure of bacteria Draw out and label the following Bacteria Factfile: Average size of microorganism: 0.5-5μm (micro meters) Cell type: Prokaryotic Task describe the following bacterial conditions and how they are transmitted:. Chlamydia. Gonorrhea. Tuberculosis An Intro to the Virus https://www.youtube.com/watch?v=8FqlTslU22s  An Intro to the Virus A virus is an infectious microbe consisting of a segment of nucleic acid (either DNA or RNA) surrounded by a protein coat. A virus cannot replicate alone; instead, it must infect cells and use components of the host cell to make copies of itself. Often, a virus ends up killing the host cell in the process, causing damage to the host organism. We say 'strains' of virus and not species. They are made of a relatively short length of genetic material DNA which is surrounded by a protein coat.  Viruses are not alive because they do not complete all of the seven life processes: Movement, Respiration, Sensitivity, Nutrition, Excretion, Reproduction and Growth. Remember viruses are not treatable by antibiotics – We rely on Vaccinations and autoimmunity Task – Find out what viruses we immunise against in the UK  The Virus Task: Draw and Label a virus Average size of microorganism: 20-350 nm (nano meters) Cell Type: N/A - Viruses are smaller than cells and lack the components that cells need to make copies of themselves. Task describe the following viral conditions and how they are transmitted:  The Lifecycle of the Virus The life cycle of a virus is the same as other pathogens. They can often survive outside a host for long periods of time – Which makes surface transmission so easy. When they have infected a suitable host cell or cells, they replicate themselves within the cell thousands of times. They do not divide and reproduce, but replicate their DNA and protein coats. These are then assembled into new virus particles. The host cell or cells then burst and other nearby cells can be infected with the virus. This process can be as quick as twelve hours in the case of the Norovirus or several Task: Draw out the process of Viral replication.  Fungi & Protists https://www.youtube.com/watch?v=zK7Ckmxxqds An Intro to fungi They are usually multicellular but some are single-celled (e.g. yeast) Multicellular fungi are mainly made up of thread-like structures known as hyphae that contain many nuclei and are organised into a network known as a mycelium An Intro to fungi Their cells contain a nucleus with a distinct membrane Their cells do not contain chloroplasts (so they cannot carry out photosynthesis) They feed by secreting extracellular digestive enzymes (outside the mycelium) onto the food (usually decaying organic matter) and then absorbing the digested molecules. This method of feeding is known as saprotrophic nutrition Some fungi are parasitic and feed on living material Examples of fungi include: moulds, mushrooms, yeasts The Structure of Fungi  Fungi Task: Draw and Label a fungus Average size of microorganism: 5-50 μm (micro meters) Cell Type: Eukaryotic Task describe the following Fungal conditions and how they are transmitted: Thrush Protocists The protocists are a very diverse kingdom of organisms that don't really belong in any of the other eukaryotic kingdoms (animals, plants and fungi) They are mainly microscopic and single-celled but some aggregate (group together) into larger forms, such as colonies or chains of cells that form filaments Their cells contain a nucleus with a distinct membrane Some have features making them more like animal cells e.g. Plasmodium (the protoctist that causes malaria)  The Features of Protocists Some have features, such as cell walls and chloroplasts, making them more like plant cells e.g. green algae, such as Chlorella. This means some protoctists photosynthesise an d some feed on organic substances made by other living things  Protocists can cause disease Some severe diseases of humans caused by protists (primarily blood parasites) are Malaria, Trypanosomiasis (African sleeping sickness), Leishmaniasis, Toxoplasmosis, and Amoebic dysentery.  Task – Draw and label a protist Task: Draw and Label a Protist Average size of microorganism: 1 μm - 2mm (Micro/Nano meters) Cell Type: Eukaryotic Task describe the following viral conditions and how they are transmitted: Malaria The others.. Prions - A prion is a protein that can cause disease in humans and animals by causing healthy proteins in the brain to fold abnormally. Prions are the infectious agents that cause neurodegenerative diseases like Creutzfeldt Jakob disease (CJD). Parasites - A parasite is an organism that lives on or in another organism, called the host, and takes food or other resources from it. Parasites harm their host in some way, but they need the host to survive. They rarely kill their host, but they can carry diseases that are life-threatening such as Toxoplasmosis Extension Task: Complete your pathogen revision table Transmissi on of Disease Using the following slides Research the 6 describe and explain the forms of transmission  Transmission by direct and indirect contact Example? - Direct contact (physically): touching, sexual contact, or contact with blood or bodily fluids (HIV or malaria) - Indirect contact: when an individual touches an object that an infected person has touched  Inhalation When breathing in the infectious pathogen, breathing in droplets/secretions expelled by a cough or a sneeze: these travel as far as 1 metre.  Inoculation An individual is injected a small amount of the disease which has been inactivated so it cannot cause harm. It’s designed to stimulate the immune response into producing the defence mechanism if exposed in the future. A more common term for inoculation is?  Ingestion Ingesting contaminated food or water. Example of infection caused by contaminated food?  Reservoirs Are a supply or source of infection. They can be humans, animals, or environmental like water, vegetation. Tetanus is an example of a condition where the reservoir for the bacteria is soil and animal faeces. The soil contains the disease, which is then transmitted through contact with soil. Most common in children playing in the garden/parks.  Fomites Are non-living objects that can cause cross-infection if they are contaminates with a pathogen. For example: door handle, bar/tram handles, hospital equipment.  Fomites Task Make a list of 5 fomites that can carry disease. (Think about the types of objects that you might come into contact with every day) For each, identify a method of preventing this from becoming a source of transmission  Asymptomatic Carriers What does this mean? An asymptomatic carrier is someone who carriers a disease but does not display the usual signs or symptoms. What problems can this cause? Vectors of Disease Transmissio n What are vectors? Vectors are living organisms. They act as a transport for pathogens to infect other organisms: between humans, between animals or from an animal to a human. Examples of vectors: mosquitoes, ticks, flies, fleas and aquatic snails. Common diseases they transmit are: malaria, dengue fever, yellow fever.  Body lice Different from lice found on the head or in pubic areas. What pathogen do they usually carry? A bacteria that causes typhus fever. Mosquitoes and malaria Serious disease caused by viruses that are carried by mosquitoes. Treatable but fatal. When an individual is bitten by the mosquito, the disease enters the liver and enters red blood cells, where it multiples. These cells will then burst and the virus spreads more throughout the bloodstream. Symptoms: fever, chills, sweating Transmission from human to human: through blood Half of the world's population is at risk of Malaria. https://www.youtube.com/watch?v=gwYIyjwYluc Ticks and lyme disease Are small blood-sucking animals that transport the bacteria that causes lyme disease Ticks are found in woodland, parks and gardens Symptoms: tiredness, pain and fever  Incubation period: time Rabies and animals between exposure to a infectious pathogen and displaying symptoms. Disease caused by a virus, present in more than 50 countries Transmitted by the bite of an infected animal Deadly: it enters the body, travels to the spinal cord and enters the brain, spreading through the nerves and causes death The incubation period is usually 2-8 weeks. Immunology Part 2 – The Immune Response To understand how the body responds to infection The explain the importance and role of the lymphatic system in the immune response To explain the difference between non-specific and specific defences The role of T and B cells in the adaptive and innate immune response White Blood Cells – also called Leukocytes* White blood cells are part of the body’s immune system, defending against infection by pathogenic microorganisms Question - Where are white blood cells produced? There are a number of types of white blood cells that all have specific adaptations and work together to keep us healthy and destroy invading pathogens The immune response The immune response is an important part of the body’s method of protecting against infection. Can you think of any ways in which the body can prevent infection? There are two main ways the body can prevent infection we call these: Non-Specific – Such as the skin barrier and mucous production, inflammation and phagocytosis Specific responses – Such as T and B cells Key Definitions Antigen: A substance recognised by the immune system as self or non-self and that stimulates an immune response Antibodies: Blood proteins produced in response to and counteracting specific antigens The Lymph System and the Thymus  The Lymphatic system Research Task Using the following website (click here) answ er the questions. 1. Where is the lymphatic system found? 2. What are the 2 main functions of the lymphatic system? 3. What is the role of the Thymus? Quizziz Join our Team - https://quizizz.com/join?showGroupJoin=true&t=q2rjGcb tDeV35cOasRwr1or-C2Spl2D2xGhV1seimyxK61fgwaYZL rbTwyCVJKjTUw9VyJfxRidOWAgjcsNi1L6o-xEENuZt6qKEw 2K1F4rUxs5KNxDreVqVcVsCNJ11ki_3uL3xjNXj20peDm6 PKZvT28R7N5-KfRY.aWfAqvDgX1Yts47x6uT6PA.jUpD_LA ZwJbcaVdS F535642 Quizziz Complete the following questions https://quizizz.com/join?gc=952969 Types of White Blood Cells Phagocytes and  Innate vs Adaptive Immunity The non-specific or innate Involves the creation of white immune response is comprised blood cells such as B and T of general protective cells which specifically target responses carried out by the an invading pathogen – body Specific immunity It is a non-specific immune It is a uniquely targeted response as the response is the response and therefore takes time to work same for any pathogenic cell – including your own cells! This is why we feel ill for a few days before we get E.g. Phagocytes engulf invading better pathogens Extension Task: Research a disease which causes the body’s own immune system to target it’s own cells Phagocytes Make up around 75% of all white blood cells in circulation Carry out phagocytosis by engulfing and digesting pathogens Involved in the ‘Innate Immune Response’ Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells – This means they are able to find and recognise invaders within our blood! Once they encounter the pathogenic cell, they will engulf it and release digestive Antigen Vs Antibody Antigen – A chemical marker found on the cell surface membrane, these are unique to the individual and can be considered 'self' or 'non-self'. The presence of a non- self antigen can trigger the immune response. Antibody – Blood proteins (produced by B cells) which target specific antigens, alerting the immune system to the presence of a foreign body. Task: Phagocytosis – Draw and Write out and put the following in the correct order 1. Digestive enzymes are released and break down the invading pathogen 2. Pathogen is surrounded by the phagocyte 3. Pathogen is detected by phagocyte 4. Pathogen is engulfed by the phagocyte  Lymphocytes Produce antibodies to destroy pathogenic cells and antitoxins to neutralise toxins released by pathogens. They are involved in the ‘Adaptive Immune Response’ – This produces a unique response to each invading pathogen and takes TIME There are two types of lymphocytes (with different modes of action). The two types of lymphocytes are: T-lymphocytes (T cells) B-lymphocytes (B cells) T Lymphocytes (T Cells) Created in the bone marrow and are stored in the Thymus Two types – Helpers and Killer T cells: Helper T cells mark foreign invaders to alert killer T cells and phagocytes to their location Killer T cells destroy invading pathogens T Lymphocytes don’t forget.. – They will be ready to attack a similar invading pathogen if it ever invades again and this time do this much more rapidly! B Lymphocytes (B Cells) B cells protect you from infection by making proteins called antibodies. Created in the bone marrow Antibodies are unique to each ‘antigen’ – A structure unique to each to an invading pathogen Antibodies ‘mark’ invaders which alert other white blood cells to destroy them, they can also help to counter the impact of a pathogen and nullify them B cells allow us to create vaccines – which are injection which contain dead version of viruses that our bodies can create B cells to fight off in future Task: Create a factfile or poster which describes the different types of white blood cells – Phagocytes and Lymphocytes (Both types) Within your factfiles you must describe: Where are the cells produced? If relevant where do they mature? What is their role in the immune response – What do they do? State whether they are part of the innate or adaptive immune response The role of T and B memory Cells in the secondary immune response Activation of T and B cells leads to production of memory cells. These remain in the body for a long time (sometimes years). Their presence ensures that on the occurrence of a second contact with an already identified antigen, the body can trigger a much quicker and stronger response. This means that we very rarely feel the impact of a pathogen that we have experiened before and forms the basis of vacciniations. The importance of Inflammation Inflammation is a localised response to injury and infection. Key changes: Blood flow increases - This helps deliver lymphocytes and phagocytes to the site of infection. Chemical Release – Chemicals are released which promote phagocytosis Swelling – Leaking intracellular fluid can lead to swelling in a localised area Exam Style Questions Complete the new assignment ‘Immune System Exam style questions’