Immunity And Pathogens Flashcards
Define disease
Any condition that impairs any normal body functions, except those resulting from physical injury
What’s a non infectious disease and example
Diseases that cannot spread from individual to another. They are genetic and lifestyle diseases such as cystic fibrosis, lung cancer and asthma
What is an infectious disease and example
Diseases caused by another organism. Can be transmitted from one organism to another. Eg mumps, chicken pox, malaria
Define pathogen
A disease causing cellular or non cellular agent
What’s the difference between cellular and non cellular
Non cellular must have a host cell to survive in
What category does prions fit into and what are they examples of diseases
Non cellular.
Responsible for neurodegenerative diseases
Can be spread from both humans and animals and can spread to humans by infected meat
Eg mad cow disease
What type is bacteria and what is it and an example
Cellular - double stranded DNA
Release waste products like toxins which affect functions of cells
Reproduce rapidly
Eg food poisoning under 60 degrees bacteria grows
What type is a virus, what are they and an example
Non cellular- can not grow or multiply on own needs host cells to help them
Cold or flu virus target cells the respiratory or digestive tracts
Comprised of three parts, nucleic acid, protein coat and lipid membrane
What’s the difference between disease and infection
Disease occurs only after body cells or organs are damaged by infections and the symptoms are visible
Infection occurs when pathogenic bacteria, viruses or other microbes gain entry to the human body and begin to multiply
What is an incubation period
The interval between a persons exposure to a pathogen and the onset of disease symptoms in the person
What are entry points of pathogens
- the nose and throats into ducts and tubes of the respiratory system
- the mouth into the digestive system
- the urethra or via genital openings into the genital tract
What is the major histcompatibility complex(MHC)
A cluster of tightly linked genes on chromosome 6 humans
They code for proteins molecules which are attached to the surface of body cells
They are sectioned into two classes to recognise own and foreign materials
What’s the two types of MHC antigens
Class 1 MHC antigens are located on the surface of virtually all human cells
Class 2 MHC antigens are restricted to macrophages and b lymphocytes
What is HLA
Human Leucocyte (white blood cells) Antigens Similar to MHC antigens
What is the two sections of HLA
Class 1 antigen- located on all nucleated cells for the body. There are three groups A B C
Class 2 antigen- located on special immune cells called B and T cells.
What occurs in the first line of defence
Physical and chemical barriers are non specific defence
- skin provides physical barrier to entry of pathogens
- skin produces chemical secretions that inhibit the growth of bacteria and fungi
- low pH
- tears, music and saliva help wash microbes away
How does the second line of defence different
Non specific defence that is a more cellular response
Cellular defence in second line of defence
Phagocytes- cells that engulf foreign particles there’s include macrophages and granulocytes.
Natural killer cells- large white blood cells (lymphocytes) that naturally target virus infected cells and cancer cells. They release chemicals that cause the cell to lyse (leak) or cause apoptosis
What are defence molecules in the second line of defence (soluble molecules)
Cytokines- act as signalling molecules that are short lasting and tend to be localised in their action
Interferon- type of cytokine that is released only in the presence of virus infected cells that signal a viral response.
Complement proteins- group of proteins that bring about a cascade of events that end in cells being destroyed.
Protective responses in second line of defence
Inflammation- release of histamines(signalling molecules) from damaged cells cause phagocytes to be attracted to the area. Causes redness and swelling
Platelets and blood proteins- form scabs preventing blood loss
Fever-increase in temperature results in a quicker response and provides an unsuitable environment for pathogens
What is the lymphatic system
Important function in the immune response occurs at lymph nodes. These become swollen and hard when fighting an infection as the lymph cells reproduce rapidly to increase numbers
Diagram of a lymph node
Photos
Function of lymph nodes
As lymph passes through the nodes it traps pathogens in fibers
Macrophages destroy them or B cells may be released.
Lymph nodes produce lymphocytes (T cells and B cells) which circulate parts of the body
What is the third line of defence
A specific response to a type of pathogen involves the two pathways cell mediated immunity and humoral immunity
What occurs in the cell mediate immune response
Everywhere a macrophage travels it can present an antigen to any T- helper cells it encounters.
The recptor on the cell is specific shape and if the antigen matches it become an active T cell. This then activated other T Cells.
The cytotoxic T cell is stimulated by the helper T cell and will search out and destroy any cells in the body that is not functioning properly
Once the infected cell is destroyed the cytotoxic and helper T cell will slowly die off because of suppressor T cells
However some still remain as memory T cells.
How does the cytotoxic T cell know which cell is infected and an example
Any cell with an altered MHC self identity protein. Eg if a transplanted kidney had the wrong MHC then it will be destroyed
What are memory T cells for
These cells response to the same antigen if ever presented again
What chemical message does the macrophage release and what do they attract
Inter leukin 1 to attract helped T cells
What chemical message does helper T cells release amd what do they stimulate and what’s the process called
Interleukin 2 stimulates cytotoxin T cells and activated B cells
Called cell mediated response
How can the B cell recognises the antigen what’s the process called
Either directly from the macrophage or stimulated by interleukins from the helper T cell
Called clonal selection
What is clonal expansion
Once the B cell is activated it divides through the process of mitosis to form more B cells that recognise the antigen
What do B cells differentiate into and what’s the difference between the two
Plasma B cells - secrete antibodies but do not live very long
Memory B cells - remains in blood stream for months/years. When pathogen is shown again these will be activated and quickly produce plasma cells
What is hormonal immunity
Can be activated by the cell mediated pathway or macrophage
B cells recognise antigen then divide to form more B cells
These cells differentiate into two types
Plasma B cells and memory B cells
What are antibodies
Proteins made in response to antigens
They recognise and bind to antigens
They are highly specific and can help destroy antigens
Each antigen has at least two sites that can bind to an antigen but must be the same type
Lable parts of an antigen
Photos
What does antibody igE do
Responsible for allergic reactions
Antibody response vs time graph
Photo
What is the second infection shorter
Due to presence of b memory cells. Straight away able to produce plasma B cells
What’s an example of a second infection
Immunisation or association
What’s the difference between primary antibody response and secondary
Primary takes longer as the humoral and cell mediated pathway are working. The antibody response decreases when antibodies are produced
Secondary response is shorter
What’s the difference between active and passive immunity
Active immunity is when B cells develop, memory cells produced and antibodies increase
Passive no B cells formed antibodies only last short amount of time
What’s the between natural and artificial active immunity
Natural- get sick because of exposure to pathogen
Artificial - vaccination exposed to an altered pathogen
Difference between natrual and artificial passive immunity
Natrual - antibodies passed on through mum via breast milk
Artificial- received antibodies in serums that will act directly on pathogens eg snake bite anti venom
What’s an automotive diesease and example
Caused when the body immune system begins to attack the body’s own tissues.
Can be triggered by drugs or pathogens
Eg multiple scierosis
What’s hypersensitivity and an example
When the immune system over reacts to an antigen or reacts to the wrong substance
Hay fever allergic reaction to air born substances such as dust, pollen and animal fur. A person becomes sensitive when they form antibodies to the the harmless substance
What is herd immunity
When 95% of the population is immunised against a disease it is very unlikely that the 5% would get the disease as there is a small chance that the unvaccinated person will come across the disease and catch it
What would happen if people don’t get vaccinated
People who are too young or too sick to be vaccinated or have views against them would be infected if there is a group of these all tother then an outbreak can occur
What are monoclonal antibodies and how do they help cancer
Antibodies that are synthetically made by a scientist in a lab.
Uses be protein on the surface of cancer cells
Create a antibody specific to the cancer proteins and have them carry radiation or a toxin to the cell to make it die
How is a monoclonal antibodies more effective on cancer cells
As the cancer cells have specific proteins the antibodies made specifically for them
Will only affect the cancer cells
This reduces chances of people becoming sick and reduces overal radiation as only cancer cells are affected
What is an autoimmune disease
A disease that is caused when the body’s immune system begins to attack the body’s own tissues by producing autoantibodies
What are triggers for the body producing autoantibodies
Viral infections, genetic factors, hormones or drugs are suggested to be possible triggers
What is multiple sclerosis and how does it occur
A progressive inflammatory disease of the central nervous system in which the myelin insulating the nerves of the Brian and spinal cord are destroyed from autoantibodies. This cause the impulses tonne slowed or blocked
What are symptoms of multiple sclerosis
Numbness, lack of coordination, slurred speech, vision impairment and fatigue
What are the steps of an allergic reaction once a person is sensitised to it and then exposed to the allergen
Step 1: the IgE antibodies on the mast cells recognise the allergin and bind to it, once they bind the IgE antibodies release histamine
The release of histamine results in an increase of blood flow causing redness, sneezing, itchy eyes and runny nose
Step 2: migration of more immune cells produce inflammation causing tissue damage and recruit more immune cells
What’s an example of an immune deficiency disease
HIV aids
How does HIV (aids) occur
Results from uncontrolled and untreated infection by HIV. The HIV targets helper T cells of the immune system, making it weaker and enables the cells to produce more and more copies of the virus as the immune system cannot fight the infection
