Intro To Immune System Flashcards
What are the primary lymphoid organs for and what organs are they?
Bone marrow. Thymus. It’s where cells develop and mature.
What are the secondary lymphoid organs for and what are the organs?
Lymph nodes. Spleen. Mucosa associated lymphoid tissues. Where immune responses are initiated.
Where do the immune cells originate from?
Hematopoietic stem cells in the bone marrow.
What can hematopoietic stem cells differentiate into?
Lymphocytes. Monocytes. Macrophages. Dendritic cells. Granulocytes.
Examples of lymphocytes.
B cells. T cells. Natural killer cells.
Examples of granulocytes.
Neutrophils. Eosinophils. Basophils.
What is the difference between innate immunity and adaptive immunity?
Innate is fast and non-specific, adaptive is slow and specific.
What are the key components in the innate immunity system?
- physical barriers like skin and mucous membrane
- cellular defences like phagocytes and NK cells
What do phagocytes do in innate immunity?
(Like macrophages and neutrophils) they engulfing and destroy pathogens through phagocytosis.
They also release cytokines which recruited more cells to the site of injury to amplify the response.
What do NK cells do in innate immunity?
They target and destroy virus-infected cells and cancer cells by inducing apoptosis.
What is the complement system?
Group of plasma cells which enhances phagocytosis, promote inflammation and direct lyses pathogens by forming membrane attack complexes (MAC).
What are the 2 main branches of adaptive immunity?
Humoral immunity and cellular immunity.
Explain what happens in humoral immunity?
1) B cells make antibodies that bind to antigens which neutralises the pathogen or marked them for destruction by other immune cells.
2) Antibodies recognise unique regions of the antigens called epitopes.
3) B cells proliferate and differentiate into plasma cells which secrete lots of antibodies and memory B cells which provide long-term immunity.
Explain what happens in cellular immunity.
1) Helper T cells secrete cytokines that activate other immune cells.
2) Cytotoxin T cells kill infected and abnormal cells by recognising antigens presented by major histocompatability complex (MHC) molecules.
Describe the connection between innate immunity and adaptive immunity.
Innate immunity its the 1st line of defence, adaptive immunity relies on the recognition of antigens. Innate triggers adaptive.
Eg. Dendritic cells (part of innate) capture antigens and presents them to T cells which initiates adaptive immunity.
Cytokines produced during innate responses help activate and direct the adaptive immune system.
Give 2 examples of autoimmune diseases.
Rheumatoid arthritis and lupus. They occur when the immune system attacks the bodies own tissues.
Give an example of immunodeficiencies.
Severse combined immunodeficiency (SCID) results from an inability to mount effective immune responses.
Give examples of exaggerated immune responses to harmless substances.
Allergies and hypersensitivity.
What are human leukocyte antigens (HLA)?
Proteins found on the surface of body cells. They are responsible for each individual uniqueness. Function is to transport antigens from within the cell to the cell surface.
Immune system uses HLA to differentiate between self and non-self cells (any cell with HLA is not an invader). HLA is dependent on which genes are inherited by parents.
Explain what macrophages do?
Kill microorganisms via phagocytosis. Monocytes mature into macrophages.
- largest phagocytise cells
- scavenge old RBC’s and neutrophils
- antigen presentation, involved in acquired immunity
Explain what neutrophils do?
Most abundant circulating leukocyte for phagocytosis.
- found in blood but can move to site of trauma/infection (diapedesis), where they destroy microorganisms by ingesting them and releasing enzymes that kill them.
- release cytokines (recruit other immune cells)
- boost response of other immune cells.
Explain what natural killer cells do?
Induce apoptosis in target cells, doesn’t attack invading cells directly.
- Recognise antigen presented by MHC1
- Receive cytokines signal and adhere to infected/tumour cells
- Releases cytotoxic proteins into target
Explain what dendritic cells do?
- boost immune response by presenting antigens on cells
- when immature can phagocytise pathogens
- when maturing, present antigen via MHC1+2
- Presentation to T cells (adaptive immune response)
Explain what happens in inflammation.
- respond via activation of innate mechanism
- macrophages release interleukin-1
- causes hypothalamus to raise body temp
- it mediates, repair and cellular regeneration
- macrophages primary responsible for mediating inflammatory response
