Immunity & Disease Flashcards
What are the 2 main pathways involved in immunity?
1) Innate
2) Adaptive
Describe innate immunity?
Occurs initially even before infection or is activated in a non-specific way
Describe adaptive immunity?
A cell-mediated response led by antigens and anti-bodies
What 4 things are involved in innate immunity?
1) Physical barriers
2) Chemical barriers
3) Cellular defence mechanisms
4) Non-specific defence mechanisms (caused by Inter-leukins released from macrophages)
Name the 2 physical barriers?
1) Skin
2) Mucous membranes
How does the skin act as a physical barrier?
1) Keratin outer layer
2) Dead skin cells fall off
3) Sweat contains anti-microbial chemicals
How do the mucous membranes act as a physical barrier?
1) The normal flow of mucous across the membranes washes the microbes away
2) Cilia (in respiratory tract)
3) Acid (in the stomach)
4) Enzymes (e.g. saliva)
Describe the chemical barriers in the body?
Chemical mediators are released from proteins.
Complement proteins = work with the body’s defence mechanisms
Interferons proteins = inhibit the replication of viruses
What are the 2 cellular defence mechanisms?
1) Granulocytes that carry out phagocytosis
2) Macrophages
Which cells are classed as granulocytes and carry out phagocytosis?
Neutrophils, basophils, eosinophils
How are the macrophages involved in cellular defence mechanisms?
In tissue = called monocytes
When activated = called macrophages
Macrophages will stimulate non-specific defence mechanisms (by releasing inter-leukin 1 and 6) and stimulates specific-defence mechanisms (by presenting antigens on their surface)
What are the 3 non-specific defence mechanisms that are stimulated by macrophages releasing interleukins?
1) Fever
2) Pain, swelling and redness
3) Acute-phase proteins are released from the liver, will bind to proteins and stimulate complement proteins
Which cells are involved in the adaptive immune response?
Lymphocytes
Where are the lymphocytes located?
Make up 1% of the blood stream and the majority are located in the lymphatic system
Name the 2 lymphocytes involved in adaptive immunity?
B-cells and T-cells
Compare where the B-cells and the T-cells are produced and where they mature?
Both B-cells and T-cells are produced in the bone marrow.
But, the B-cells mature in the bone marrow whereas the T-cells mature in the thymus gland.
Once mature, they both circulate in the blood and lymphatic system
Compare the roles of B-cells and T-cells?
B-cells: Humoral immunity, release antibodies and present antigens on their surfaces to activate T-cells
T-cells: Cell-mediated immunity
Compare what B-cells and T-cells recognise?
B-cells: Recognise antigens outside of the cell
T-cells: Recognise antigens presented on the surface of other cells
Compare the of B-cells and T-cells?
B-cells: Only 1 type
T-cell: 2 types
Describe the 2 types of T-cells and their function:
CD8 (cytotoxic) T-cells: Attacks pathogens
CD4 (helper) T-cells: 1) Help the B-cells to release antibodies and 2) Activates CD8 T-cells and macrophages in order to attack the pathogens
What is an antigen?
A protein marker on a cell’s surface
What is an Epitope?
A fragment of an antigen
How does HIV cause a diminished immune system?
HIV (human immunodeficiency virus) destroys T-helper cells (CD4) which causes a diminished immune system and results in AIDS (acquired immunodeficiency syndrome)
Describe the immune response in steps (starting with the innate immune response and then the adaptive immune response):
Innate immune response:
Granuloytes will carry out phagocytosis and macrophages will present the pathogens antigens on its surface.
Adaptive Immune response:
1) B-cells will recognise the antigen product specific antibodies and present the antigen on its surface
2) CD4 T-helper cells recognise the antigen presented by the B-cell and help the B-cells to secrete antibodies
3) The B-cells will divide into plasma cells (that release antibodies) and memory cells.
4) CD4 T-helper cells will then activate macrophages and CD8 cytotoxic T-cells to directly destroy the pathogen
What 3 problems can occur with the immune system?
1) Immunodeficiency
2) Over activity/hypersensitivity
3) Autoimmunity
Name 5 examples that causes immunodeficiency?
1) HIV
2) Splenoctomy
3) Organ Transplant
4) Chemotherapy
5) Bone marrow dysfunction
Name 2 examples caused by an over active immune system?
1) Allergy
2) Sepsis
Define autoimmunity and what causes it?
Autoimmunity is whereby the body is unable to recognise self cells and so the immune system will fight against self cells.
It is caused because:
(Normally when the embryo is developing, lymphocytes that recognise self-cells are deactivated and destroyed) But in autoimmunity, these self-recognising lymphocytes are reactivated.
Name 4 examples of autoimmunity diseases?
1) Multiple sclerosis
2) Rheumatoid Arthritis
3) Type 1 diabetes
4) Coeliac disease
When is the immune system manipulated?
1) Organ transplantation - suppressing the immune system so the body is less likely to reject the organ
2) Immunotherapy - in cancer
3) Immunisation/vaccination - introducing an inactivated pathogen to the body, so B-cells can produce specific antibodies to it. Memory B-cells are formed so that if injected again with the same pathogen, these memory B-cells can produce the specific antibodies against it.
What are the 4 types of vaccination/immunisation?
1) Live (but weakened)
2) Inactivated
3) Taxoid (bacterical toxin)
4) Conjugated (antigen linked to a protein carrier)
