Immunity Flashcards
What is the lymphatic system comprised of?
Lymph
Lymph nodes
Lymph vessels
Define lymph fluid
Travels through a system of vessels and baths all body cells allowing them to drain into the vessels
What special feature do lymph vessels have?
They have valves which control a one way motion of fluid
Why does the lymph rely on for movement
Muscle contraction
What is the relationship between the circulatory system and the lymphatic system?
Joins up at the neck and drains into the blood stream
What is blood composed of
- Red blood cells
- White blood cells
- Platelets
What is another name for white blood cells?
Leukocytes
What is the red of the red blood cell
To transport oxygen around the body
What is the role of the leukocytes
Cells that have specific roles in 2nd and third line of defence
Explain all three lines of defence
- Barrier to prevent the entry of the pathogens into the body
- Non-specific immune response: try to destroy every pathogen that is encountered
- Specific immune response only attack specific pathogens
What can the specific and non-specific also be known as?
Adapative and Inate
Explain the first line of defence
The first round of defence mechanism that they meet is a non-specific response which is a range of chemical and physical barriers.
NO MEMORY of the pathogen is formed after the invasion
List the chemical barriers for the first line of defence
-Acids
-Enzymes
-Mucous Membrane: traps microorganisms
-Tears
Sebum
List the physical barriers for the first line of defence
- intact skin: waterproof layer
- cilia: filter air
- nasal hairs: filter air
- hair
- ear wax: traps pathogens
- eyelashses
What are “non-self” molecules
Foregin cells or particles
What are self molecules
Molecules that belong to that particular organism
Define Antigen
A foreign substance that causes the immune system to make a specific immune response
Where are MHC markers founds?
proteins that are found on the surface of the cells membrane
Are all MHC markers the same
Determined by genes therefore each individual has their own MHC markers
What do MHC markers allow?
The body to recognise that the cell belongs to itself
What are the two classes of MHC markers and explain them
Class 1 MHC- Found on all body cells that have a nucleus
Class II MHC- Located on antigen presenting white blood cell: B and T lymphocytes
Where do all blood cells come from?
Bone marrow of the long bones in the body
What are all blood cells derived from?
Stem Cells
What is the one group of cells that do not mature in the bone marrow?
T cells leave the bone marrow and mature in the thymus
Is there any memory pathogen formed in the second line of defence?
NO
Define phagocytes
They are white blood cells that move to the point of pathogen entry and are formed in the bone marrow.
Where are phagocytes located?
Normally will move freely through the lymhatic and circulatory system, but will leave in order to track down pathogens
How do phagocytes get rid of the pathogen?
They engulf the pathogens via endocytosis and then will digest the pathogen
Explain a macrophage
They have a long life span and work on various agents
-They detect and destroy by following the chemical trail of the microbe
What if the pathogen is too large for the macrophage to destroy it?
Many phagocytes attach to the pathogen
What happens when a macrophage is injesting a pathogen?
Will display the antigens fragments on its own cell surface in order to activate other parts of the immune system
Explain neutrophils
Most common type of white blood cell, live a short live span and can squeeze in between cells
Explain eosinophils
Secrete enzymes to make holes
Explain Basophils
Secrete histamines causing inflammation
Explain Natural Killer Cells
They attack and kill viral-infected cells by attacking their cell membranes and causing them to lyse
Explain complement proteins
Group of proteins that assist phagocytes in recognising pathogens
Where are complement proteins found?
They continually circulate in the blood
Where are complement proteins secreted from?
Macrophages
When do complement proteins become activated?
When encountering a foreign body and activating one causes another to be activated (domino effect)
How do complement proteins function?
Attach to antibodies on the invading micro-organism and act as flags making the pathogen more identifiable and attracting more phagocytes to it
What do complement proteins do when they come in contact with bacteria and fungi?
They lyse the cell causing their substances to leak out.
Define Cytokines
Chemical signals that allow communications between cells
Explain interferons
- Secreted byy virally infected cells
- Induces resistance to viral infection in the surrounding cells
- Act as a warning signal from the affected cell to other cells
What causes inflammation?
Histamines released from mast cells causing local aterioles to exapand
What happens during inflammation?
Capillaries dilate and permeability of the blood vessels increase
What are the benefits of inflammation?
Neutrophils and macrophages are able to squeeze into the infected tissue.
-Pain causes reduced voluntary movement in the area
What is fever telling us
That there is an infection
Explain the process in getting a fever
Macrophages release interleukin-1
-interleukin sends a message to the hypothalamus causing the body temperature to rise
What are the benefits of a fever?
High temperature is not good functioning environment for the pathogen
-Interleukins cause drowsiness thus allowing more energy to be used for destroying pathogens and repairing damaged tissues
What are lymph nodes?
Sections along the lymph vessels in which contain white blood cells
Why do lymph nodes swell in infection
White blood cells are multiplying at a rapid rate in order to over come the invader
Where do the B cells mature
Thymus
What is the third line of defence
Specific
Explain humoral immunity
-involves the resistance to disease via the production of antibodies that bind to specfic antigens
Give an overview of humoral immunity
- B cells divied when stimulated by non self MHC
- Produce plasma B and memory B
- Plasma B produces a large amount of anitbodies
- Memory B cells will stay in body to help protect against that particular pathogen again
Define anti-body
A protein molecule produced by B cells designed to attach to only one type of antigen
Where do B cells carry the antibodies
Cell membrane
List the types of Pathogens and their functions
IgM-Affective in aggulation and allow easy disposal via phagocytosis
IgG-Activate complement proteins and can neutralise toxins directly
IgA -Neutralises pathogens in respitory, digestive and reproductive tract
IgD-Antigen receptor on B cells
IgE- Initiate inflammation causing an allergic rection
What happens when the antigen is presented to the B Cell?
Rapidly divides and clones into plasma B cells and memory B cells
What do plasma B cells do
Produces free antibodies at a rate of thousand/second and release them straight into the blood stream.
What happens to the antibody used to fight the infection
Remains attached to the memory cells
Longevity Memory vs plasma
Memory cells last a long time where as plasma cells die within days via apoptosis
List four ways in which antibodies help to destroy pathogens
- Coat pathogens and neutralise particles by blocking binding sites
- Agglutination of antigen-bearing particles exposes the pathogens to being engulfed by phagocytes
- Precepipataiton of soluble pathogens
- Antbodies activate complement proteins which cause the cellular pathoegn to lyse.
Explain what happens in a secondary immune response
Occurs due to secondary exposure due to the same pathogen.
B cells react a lot faster and anti-bodies are produced at a much larger rate due to memory cells
-Usually will not suffer symptoms
Explain Antigen Presenting Cells
-have receptors on their membranes that bind to antigens
e.g macrophages
Enhance response as they take the antigen to other immune cells e.g B and T cels
When does the primary response occur?
When first come in contact with the pathogen
What happens in the primary response
- Macrophage eats the pathogen and essentially puts the pathogens and antigens on their own membrane.
- The antigen fragment is displayed on a Class II MHC marker
- The macrophage then releases interleukin (which attracts t-helper cells)
- Helper T cells then release interleukin-2 and this activates B cells and ctyotoxic T cells and more helper T cells
Explain the process of cell mediated immunity
- Macrohpage engulfs then displays antigen
- Then carried to the lymph node where lots of T cells are waiting
- It also releases interleukin I to attract T helper cells
- Then more T helper cells have become stimulated and B cells and cytotoxic T cells and more T helper cells have been activated
- Cytotoxic T cells will kill body cell that have the pathogen
- Then finally suppressor T cells turn off the specific immune response
List the three types of T cells
Helper
cytotoxic
suppressor
Explain Helper T cells
Recognise antigens that are bound to B cell antibodies or have been engulfed and displayed on the surface of a macrophage. They release interleukin 2- which mobilises and activated B and T cell
Explain Cytotoxic T cells
Explain T Suppressor Cell
Regulates the action of lymphocytes and stops activity when the invader has been defeated. Helps the system to not overreact and waste resources.
- Directly kills immmune cells
- Inhibits secretion of immune cells
- Secretingg proteins that alter immune cell function
Explain Organ Transplant Rejection
-Donors organs contain foreign antigens therefore the receivers immune system will produce anti-bodes against it and that will cause the body to reject the organ.
How can organ transplant be solved?
Drugs such as cyclosporine have been developed to lower intensity of the immune system so it does not reject with the antigens
Explain RHESUS factor ini regards to pregnacy
- RHESUS is a blood group which has positive and negative sides to it and is determined by genes
- If the mother is RH- and her first child is Rh+ then she will have memory cells for the Rhetus antigen. IN subsequent preganancies Rh+ babies that baby may be at risk from an immune response from the mother
Give an overview of vaccination
- Contains dead or weakened organisms, invert particles, toxoids or component vaccines
- Injected into the blood strem to cause the production of B cells
- If someone who has recieved the vaccine comes incontact with the pathogen the response will be alot faser
Describe Live vaccines
Bacteria or virus that has bee altered usually created from the germ itself, Viruses are weakened by growing them over and over in a lab
Explain killed vaccines
Killed bacteria or inactivated virus
Describe Toxoid viruses
Contain toxins that are produced by the germ
Explain component vaccines
Pars of whole bactieria/viruses
Define Acquired Immunity
Immunnity to a disease is either inherited or acquired. Acquired can be classifed as natural or artfiical
Deine NAtural Immunity
Natural exposes from everyday life to an antigen
Define artifical immunity
Immunisation or vaccination, deliberate exposure to a pathogen
Define active immunity
Occurs after exposure to antigen, the individuals own immune system responds to it
Define NAatural Active
Occurs when you naturally come across a pathogen
A memory is formed
Define Artifical Active
Occurs via vaccination
A memory forms
Define passive immunity
Results from the transfer of antibodies
Define Natural Passive
Antibodies that are recieved naturally e.g via breast feeding
Define Artifical PAssive
Antibodies receivesd via an injection e.g snake antivenom
Explain Auto Immune Disorders and give an example
The immune system attacks its own tissue belonging to itself, and attacking tissues with ‘self” MHC markers. In these diseases the immune system mistakenly attacks particular tisse
e.g Muliple sloriss
Explain allergic Reaction
-Excessive immune responses upon renewed exposure to usually harmless antigens
What occurs in an allergic reaction
One type of antibody IgE is produced and binds to mast cells which then release vesicles of histamine into the blood stream
What does increased levels of histamine cause>
- Swelling and inflammation
- Contraction of smooth muscle e.g lungs
What are complement proteins?
A group of proteins that assist phagocytes in recognsing the prescence of pathogens
In the primary response of specific immunity
A macrophae captures the protein and will advertise some of its antigen it on its own cell membrane, the antigen will be advertied on the MHC Class II marker
- It will then release interleukin 1 to attract T-helper cells
- T-helper cells will then release interleukin 2 and this willa ctive B cells, cytotoxic T cells and more t helper cells
Define cell mediated immuity
Involved the resistance to disease in resulting from the action of cells. It involves the attack on pathogens which are inside cells.
What are the four types of T cells involved in cell mediated immunity
Helper
Cytotoxic
Suppressor
Memory
Briefly explain the steps in cell mediatd immunity
- Antigen is displayed on macrophages on cell membrane
- Carried to lymph node where T cells are accumlulated
- Macrophage release interleukin 1 to attract helper T cells
- T cells bind to antigen and amplify the signal
- After recoognition helper T cells stimulate other helpter T cels, cytotoxic T cells specfifc to that disease to be activated, done by releasng intereukin 2
- Cytotoxic T cells kill body cells that have been infected with the pathogen, secrete proteinis and punch holes in the membrane of the infected cell, killing it.
- T supressor cells turn offf the specfic immune system for that disease.
Explain the role of T memory cells
Ability to recognise foreign antigens so that a rapid response occurs on subsequent invasions.
Define humoral immunity
Resistance to disease by the production of antibodies that bind to specific antigens
What does an antibody look like?
- Four chains
- Two heavy
- Two light
- Two antigen binding sites.
Outline Humoral Immunity
- body is invaded by pathogen (antigen)
- Macrophages carry antigen to lymph nodes
- Antigen acttivates B lymphcytes
- B lymphocytes enlarge and divide into some B memory cells but mostly plasma B cells
- Plasma B cells will then secrete antibodies and this will kill the cell.
Contrast specific and non-specific immunity
non-speciific immunity no memory
specific immunity produces speciliased cells and has mmory produced.
What are some plant defence systems against pathogens?
- Dropping leave
- Thick waxy xuticles
- Thickened cell walls
