Week 2 - Immunity And Disease Flashcards
(37 cards)
What are the different types of immunity?
Innate
Adaptive
What is innate immunity?
Defence mechanisms present even before infection or activated in a non-specific way
- skin, mucous membranes
- phagocytic cells (neutrophils,macrophages), inflammation, fever
What is adaptive immunity ?
- cell-mediated immunity
- humoral immunity
What are non-specific defences in the body?
- intact skin
- mucous and cilia
How is the skin a barrier to infection?
- outer layer = keratin - mechanical barrier
- dead skin cells constantly sloughed off (hard for bacteria to colonise)
- sweat and oils contain anti-microbial chemicals
What mucous membranes help prevent infections occurring?
- cilia - respiratory tract
- acid - stomach, vagina
- enzymes - saliva, eye
Name the granulocytes and what they do
Neutrophils, eosinophils and basophils
- remove dead cells and micro-organisms
- attracted by an inflammatory response of damaged cells
Name the monocytes and what they do
Macrophages
- in tissues which serve as filters trapping microbes
- macrophages live longer than granulocytes
- stimulate specific immune response (antigen-presenting)
How do macrophages create a non-specific response to infection?
- release protein signals - interleukin-1 (IL-1) and interleukin-6 (IL-6)
Name other non-specific responses to infections
- fever
- pain,swelling, redness
- acute-phase proteins released from liver (bind to bacteria and activate complement proteins)
What does specific/adaptive immunity rely on?
Antigens
-specific substances found in foreign microbes
What other types of cells in the lymphatic system are used in adaptive immunity?
Lymphocytes (b cells and T cells)
-carried in blood or lymph
Where are lymphocytes produced?
Bone marrow
-B-cells mature in bone marrow then concentrate in lymph nodes and spleen
T-cells mature in the thymus
What antigens do T-cells recognise?
Antigens presented by major histocompatibility complex - class I (all cells) or class II (APC)
What do T-cells do?
- directly attack invaders (cytotoxic, CD8+, MHC I)
- cell mediated immunity
- recognise pathogens that have entered cells
- also help B-cells (helper cells, CD4+, MHC II)
What do cytotoxic T-cells do?
- seek out and destroy any antigens in the system and destroy microbes tagged by antibodies
- some can recognise and destroy cancer cells
- variable region on T-cell receptor
What do T helper-cells do?
- stimulate B-cells
- activate cytotoxic cells and macrophages to attack infected cells
What is immunity?
Protection/defence against infections
How do T-cells recognise an invader?
- detect antigen on cell surface or epitope (fragment of antigen)
- if a non-self antigen protein is encountered by a macrophage, it will bring the protein to a helper t-cell for identification
- if helper t-cell recognises it as non-self an immune response is launched
What does HIV destroy?
Helper t-cells - so immune response diminished
What is the other name for helper t-cells?
CD4+
What do cytokines stimulate?
B-cell division
What do b-cells differentiate in to?
Memory and plasma cells
What do b-cells do?
- secrete antibodies (glycoproteins/specific, hypervariable region, different subtypes - IgG, IgM, IgA, IgE, IgD)
- humoral immunity
- recognise pathogens outside cells
- opsonisation, bind and block (agglutinate) stimulate complement
- become memory or plasma cells
