Immune System Flashcards
Immune system contents
Tonsils
Adenoids
Spleen
Lymph nodes
Lymph vessels
Thymus
Bone marrow
Bone marrow is the site of…?
Haemopoiesis (forming blood cells)
Functions of immune system
Recognise and kill pathogens/infected cells
Remove dead cells
Wound healing
Surveillance/removal of cancerous cells
3 types of white blood cells
Granulocytes- have specific granules in cytoplasm eg neutrophils, eosinophils, basophils
Lymphocytes- T cells, B cells, natural killer cells
Monocytes- found in blood only, immature
Neutrophils
Target bacteria/fungi
Found in bloodstream and tissues
First line of defence (innate, non specific)
Eosinophils
Attack parasites - release hydrolytic enzymes
Involved in allergic reaction
Basophils
Like Large tissue mast cells located outside capillaries in the body
Mast cells and basophils release histamines, bradykinkin and serotonin
Role in allergic reaction
Macrophage
Type of white blood cell
Derived from monocytes, found in tissue e.g alveolar macrophages in lungs, microglia (macrophages of CNS)
Innate immunity
Non specific, first line of defence
Neutrophils, monocytes, macrophages, granulocytes, natural killer cells
(Cell mediated)
Fast response
Phagocytosis
3 major groups of phagocytic cells involved in innate immunity
Neutrophils (cytokines, chemotaxis)
Macrophages and monocytes (same cell different location)
Organ specific macrophages
Interferons
Nonspecific short acting resistance to viral infection
Act as messengers that protect other cells in the vicinity from viral infection
3 types of interferons
Alpha
Beta
Gamma
Endogenous pyrogens
Cytokines that cause a fever eg interleukin, stimulate hypothalamus to raise temp and induce fever.
Inhibits bacteria, increases neutrophil and interferon production
Phagocytosis
Phagocyte attracted to pathogen by surface antigens/chemoattractants, move via chemotaxis
Engulf pathogen in phagocytic vacuole
Lysosome fused with vacuole and releases lysozymes
Lysozymes hydrolyse pathogen
Phagocyte presents pathogens antigens on surface, becomes an antigen presenting cell
Inflammation
Physiological response to infection (swelling, heat, pain, redness)
-Vasodilation to increase blood flow to effected area (increased action of neutrophils)
-increased vascular/capillary permeability, fluid leaks into interstitial spaces
-increased clotting factors
-pus formation (dead cells)
-increased production of granulocytes/monocytes by bone marrow
-walling off inflammation to specific area so infection doesn’t spread (clotting mesh formed)
-neutrophilia (overproduction of neutrophils)
Adaptive immunity?
Aquired, specific to attacking pathogen
Second line of defence (Humoral)
T cells , B cells, antibodies
2 stages of adaptive immunity
Cell mediated- T cells, b cells
Humoral - Antibidies
Types of T lymphocytes
Helper T
Cytotoxic T/ killer T
Suppressor T
Memory T
Activation of T lymphocytes? - MHC
Antigen presenting cells (e.g macrophage /phagocyte) contain MHC proteins that stick to antigen of pathogen
MHC 1 proteins present antigens to cytotoxic T cells
MHC 2 proteins present antigens to helper T cells
Helper T cells
Kickstart the immune response and regulate it
Activated macrophage system
Produce lymphokines eg interleukin -1 that act on the immune system eg to stimulate macrophage production
Stimulates B cell growth- differentiation into plasma cells- antibodies
Stimulates cytotoxic T cells
Cytotoxic T cell
Directly kills microorganisms / cancer cells/ sometimes own body cells
Bind to pathogen and secrete perforins, create holes in pathogen, release cytotoxic substances into cell
Suppressor T cells
Suppress action of cytotoxic T cells to prevent harm to body cells
Memory T cells
Produced after primary response
2nd exposure= memory T cells released, faster response
How are b lymphocytes converted into antibodies
B cell- lymphoblast- plasmablast- antibodies
(Memory b cells)
Antibodies types
IgE
IgG
IgM
IgD
Structure of antibody
Heavy and light chains, joined by hinge region
Constant and variable region (variable= antigen binding sites at the top)
IgE function
Role in Allergic response
How do antibodies protect the body
Agglutinate pathogens together for easier phagocytosis
Lysis of pathogens
Precipitation of pathogens (make insoluble)
Activate complement system
Complement system?
Collective term for Group of proteins in plasma involved in immune response and fighting infection together
Where are T cells produced?
Thymus
Active immunity
Direct contact with the pathogen/antigen, body produces own response/antibodies.
either via vaccine or naturally.
Passive immunity
Antibodies given via immunisation vaccine/ passed to baby from mothers milk
Active vs passive immunity?
Active: takes longer to become immune, experience symptoms of illness, produce own memory cells, longer lasting immunity
Passive: faster, shorter immunity
Immune mechanism of allergy (what happens?)
-Antigen presenting cells present allergens to T heler cells
-T helper cells stimulate IgE production by B cells, secreted by plasma cells
-IgE bind to receptors on mast cells and basophils (SENSITISATION)
-When allergen antigens bind to IgE on mast cell/basophil, they are stimulated to degranulate, releasing histamines/prostaglandins/leukotrienes into bloodstream (released from granules)
-causes physiological events of inflammation (vasodilation, increased vascular permeability)
-more eosinophils, basophils are recruited to contribute to inflammation
Difference between basophil and mast cell?
Basophils circulate in the blood whilst mast cells are found in tissues
Anaphylaxis
Life threatening allergic reaction, develops rapidly , causing rapid swelling and inflammation
Anaphylaxis triggers
Insect bites
Food
Drugs
