Theme 1: Immunity Flashcards
What are the four main groups of microorganisms?
Virus
Bacteria
Fungi
Parasites
What are bacteria?
Bacteria are single-celled organisms that do not have a nucleus - referred to as prokaryotic cells. Instead of having a nucleus they have free strands of DNA.
Bacterial cells have the ability to rapidly multiply when given the right conditions to do so, through a process called binary fission.
What are viruses?
Viruses are not living organisms, as they do not demonstrate all seven characteristics of life. Viruses are protein coated strains that contain lengths of DNA.
Unlike bacteria which can replicate themselves in any suitable environment, viruses replicate themselves within human cells. This is why viruses are much more difficult to combat than bacteria. Viruses cannot be treated with antibiotics, unlike bacteria.
What are fungi?
Fungi do have a nucleus and they come in all shapes and sizes. Some a multicellular such as mushrooms. Fungi can cause problems that relates to thrush in areas that have moisture, warmth and food sources. Examples include athletes foot, genital thrush and oral thrush. Fungi can be treated with anti-fungal medication which eliminates the growth of fungi
Not all are dangerous (i.e yeast)
What is a parasite?
A parasite is an organism that relies on another organism to survive. They can live either externally on the skin, such as fleas and ticks, or internally such as tapeworms.
Parasites take advantage of nutrition from the organism (called the host), wherever it is feeding on blood, or directly absorbing nutrients from the gastrointestinal tract.
Parasites don’t want to kill the host as they rely on them, but parasites can carry diseases or cause changes such as weight loss that can be life-threatening.
What are the 4 things that create the right environment for microorganisms to grow, multiply and thrive?
** food. Moisture. Warmth. Time. **
What will recede the risk of developing the risk if illness from microoorganisms?
Hand washing
What are good microorganisms found?
They do not cause an immune response, called colonisation
> this includes microorganisms that live on skin, mouth and airways
colonel microorganisms
What are the 4 modes of transmission?
Direct contact: contact with lesions, touching an infected host or sexual intercourse
** Indirect contact: ** environmental contamination, touching contaminated surfaces/objects, needle stick injuries.
** Air-borne (inhaled): ** Droplets are spread through the air
** Faecal-oral transmission ** - usually from contaminated food or water sources.
What is the chain of infection?
Microbe/organism > reservoir > portal of exit > mode of transmission > portal of entry > susceptible host
What are the three ways to prevent the spread of microorganisms?
Cleaning - Physically cleaning a surface with soap and water to remove visible organic matter.
Disinfection - Process of killing or removing pathogenic microorganisms. Use of alcohol or bleach based products are used achieving 99.9% eradication of microorganisms.
Sterilisation - Complete removal of all living microorganisms.
What are the two toes of immunity?
Innate immunity - these are structures that have been present since birth, providing us with the first line of defence to all invading pathogens, making this type of immunity non-specific.
Acquired or specific immunity - this type of immunity is acquired across our lifespan when we encounter different types of pathogens. This allows the immune system to trigger a specific response that will combat a pathogen quickly.
What are the 4 structures and cells that are involved in innate immunity?
** Physical barriers
Mechanical barriers
Chemical barriers
Leukocytes (white blood cells) **
What is the physical Barrie’s in innate immunity?
Parts of the body such as the skin and areas that have a mucous lining provide physical protection against pathogens.
The skin covers and protects our internal structures, as well as producing sebum from the sebaceous glands which has antimicrobial properties.
Mucous membranes in the nose, mouth, urethra, vagina and anus provide additional protection by trapping pathogens with mucous.
What are the mechanical barriers in innate immunity?
these are areas that contain cilia or has the ability to produce tears.
Cilia line the respiratory tract to help move mucous and particles away from the lungs.
Coughing and sneezing is another mechanical mechanism that expels pathogens and foreign particles entering the respiratory tract. Tears help to wash away pathogens and dirt away from the eyes. Tears contain lysosomes which can help degenerate microorganisms.
What are chemical barriers in innate immunity?
Tears are also chemical barriers, but also saliva, sweat and breast milk provide chemical barriers because they contain enzymes or antibodies that help protect against pathogens.
Gastric juice, vaginal secretions and semen are also considered chemical barriers due to being either more acidic or alkalotic that can help degenerate microorganisms.
What are leukocytes and platelets in innate immunity?
These are white blood cells and platelets that are present in the bloodstream which circulate round to provide a first line defence against pathogens.
How many types of white blood cell are there?
5
Where are white blood cells produced?
All blood cells are produced by the bone marrow from blood stem cells.
What are the two different stem cells that create different white blood cells
- Lymphoid stem cell > T cells, B cell lymphocytes and natural killer cells
- Myeloid stem cells > macrophages, neutrophils, eosinophils and basophils (the last three grouped together are called granulocytes).
Different white blood cells belong to different types of immunity, what are the white blood cells for innate immunity?
first line of defence
- neutrophil
- macrophage
- dendritic cell
- NK cell
- innate lymphoid cell
What do neutrophils do?
Neutrophils being the most abundant of white blood cells arrive first, attracted by the inflammatory mediators, and squeeze through the capillary walls which has become more leaky, and enters the interstitial fluid space where the mast cells and invading microorganisms or toxins released by microorganisms are found.
The neutrophils work as part of the first line of defence, while platelets start to repair damaged cells.
What are the lymphocytes two roles in acquired immunity?
T-cell lymphocytes > produced in bone marrow, mature in thymus gland > in thymus they learn to differentiate to combine specific antigens > travel through lymph nodes and spleen
**B-cell lymphocytes ** > produced in bone marrow > mature in bone marrow > only respond to forgein antigens > done by negative selection, only B cells that do not react to own body leave > have specific surface antigens
What are antibodies?
Antibodies are produced by plasma cells, a type of B-cell lymphocytes that are often called immunoglobulins.
They are protein based substances that are generated to target specific antigens, like a lock and key mechanism.
They attach to antigens by attaching to special receptors on the antigen called epitopes, which helps disable the antigen, such as prevent it from multiplying.
Also, antibodies act like a flag for other white blood cells such as T-cells or phagocytic white blood cells to aid the destruction of the foreign particle.
What is the cell mediated response
- Killer T cells (Cytotoxic T-cells) target cells with lls with specific antigens, Once bound, they release enzymes into the foreign particle to destroy it from the inside out They can also produce substances that re-program foreign cells to self-destruct (apoptosis).
- helper T-cells release a substance called cytokines, which stimulate B-cell lymphocytes and Cytotoxic T-cells, as well as draw in additional neutrophils and phagocytic white blood cells.
- Regulatory T-cells: These white blood cells help to suppress the activity of T and B-cells, which results in a reduction in the immune response once the antigens are destroyed. This prevents overactivity of the immune system which could be dangerous to the body.
- Memory T-cells: These white blood cells when exposed to specific antigens will remain alive, whilst most other T-cells would have died in the conflict. By surviving, that can reactivate if the same antigen was to enter again, allowing a quicker and more focused response to the antigens. This is a characteristic of the secondary immune response.
What is humoral immunity?
Way the immune system remembers specific antigens, just as Memory T-cells do. However, as stated earlier B-cell lymphocytes are developed to not target any body cells, only foreign antigens. On the surface of B-cells, they have receptors to specific antigens, which if triggered causes the B-cell to rapidly multiply, this is called cloning.
Two types of mature cells are created, plasma cells and memory B-cells. The plasma cells secrete antibodies which as discussed before, help to disable or/and destroy specific pathogens depending on it’s antigens. The memory-B cells will not immediately produce antibodies, so it will circulate around in the blood until they meet the antigen again. If it meets the same antigen again, it can rapidly divide into mature plasma cells with antibodies.
What are the primary and secondary responses
The primary response is the first time the immune systems meets a specific antigen. The innate immune system will react as it usually does because it has a non-specific response. However, the acquired immune system needs time to produce the correct antibodies to disable the antigens.
the second time the same antigen comes along, the immune system will have the antibodies ready, meaning it can respond faster and more effectively. Thus, providing us with a secondary immune response.
What is the fluid that circulates around the lymphatic system?
specialised fluid called lymph that is formed by plasma that has leaked from blood capillaries
What are lymph nodes?
Bean shaped structures that filter out foreign substances that might have enter the lymph fluid.
There are high concentrations of lymphocytes within the lymph nodes which contribute to destroying or disabling any substances that could cause harm to the body, such as pathogens. They help distribute lymph fluid through-out the lymphatic system, which is why there are hundreds of lymph nodes in our bodies
What are the two ways immunisations work?
This can be achieved by either activating the body’s immune system (active immunity),
via transfer of antibodies to an individual who does not have the specific antibodies (passive immunity).
What is passive immunity acquired in vaccines
Artificially acquired passive immunity can be given via immunoglobulin injections, designed to target a large concentration of pathogens.
