Overview of Immune System Flashcards
(19 cards)
What is the role of the immune system?
1) Recognise and eliminate dangerous non-self organisms/substances - defense against microorganisms and tumour cells
2) Apoptosis of cancerous/infected cells
3) Homeostasis of abnormal/dead cells (e.g., removes necrosis)
What are some mechanical physiological barriers?
1) Lacrimal apparatus - continual washing and blinking prevents microbes from settling on eye surface
2) Coughing and sneezing - expel foreign objects
3) Rapid passage of air over turbinate bones, hairs - removal of particles
4) Mucus - thick secretion that traps many microbes
5) Flushing of urinary tract
What are some chemical physiological barriers?
1) Lysozyme in tears and saliva
2) Sebum - oily substance produced by sebaceous glands forms a protective layer over skin, contains unsaturated FAs which inhibit growth of certain pathogenic bacteria and fungi
3) pH @3-5 - caused by lactic acid and FAs (pH 2 for stomach, pH 5 for skin)
4) Perspiration - produced by sweat glands contains lysozyme (enzyme that breaks down gram-positive cell walls) and acids
What is the function of the skin and mucosal epithelia?
1) Largest anatomic and physiologic barrier to penetration of microbes
2) Largest surface of interaction with environment interacting with commensal microorganisms regulating immune homeostasis and local immune responses to pathogens
What are activated by epithelial cells?
Soluble proteins such as chemokines, cytokines
What components are in the innate response of the immune system?
1) Cellular components
2) Humoral components
What components are in the adaptive response in the immune system?
1) Cell-mediated (T+B Lymphocytes)
2) Humoral (Abs, cytokines)
What are the features of the innate immune response?
1) Immediate inbuilt immunity
2) Present from birth
3) Not pathogen-specific, uses receptors with broad specificity
4) Not enhanced by 2nd exposure - no pathogen specific memory
5) Uses cellular + humoral components
6) Is poorly effective without adaptive immunity
7) Triggers and amplifies adaptive immune responses
What are the features of adaptive immune response?
1) Immunity established to adapt to infection
2) Learnt by experience
3) Uses receptors with narrow specificity
4) Confers pathogen-specific immunity
5) Slower response
6) Enhanced by 2nd exposure
7) Has memory prior exposure
8) Uses cellular + humoral components
9) Is poorly effective without innate immunity
What depends on leucocytes?
Adaptive and innate immunity
What mediates innate immunity?
Granulocytes
What is mediated by adaptive immunity?
Lymphocytes
Where is the site of activation and maturation of T-cells?
1) Maturation is in thymus (central lymphoid organ)
2) Lymph nodes, spleen and peyers patches for activation
Where is the site of activation and maturation for B cells?
1) Maturation - bone marrow
2) Lymph nodes, spleen and peyers patches in peripheral lymphoid organs
What are some structures in the peripheric lymphoid organs?
1) Lymph nodes
2) Spleen
3) Mucosal-Associated lymphoid tissue (MALT)
4) Gut-Associated lymphoid tissue (GALT)
5) Tonsils in pharynx mucosa
6) Peyer’s patches in lining of SI
What is lymph?
Clear water - fluid that seeps out of blood at peripheral capillaries
What is the function of high-walled endothelial venules (HEV)?
Allow entry of lymphocytes from blood
What is the role of peripheral lymphoid tissues?
1) Trap Ag-containing phagocytic cells and concentrate cells together to promote cell-cell contact
2) Activate all leucocytes (B + T lymphocytes, NK cells)
What is the function of lymphocyte recirculation?
1) Passes from blood to lymph nodes
2) Allows constant surveillance for presence of Ag for which lymphocyte has specific receptor on its surface
3) If specific Ag not present, lymphocytes leave node and recirculate
4) Virgin (naive) lymphocytes have finite lifespan (weeks) unless they come in contact with Ag
5) Memory cells become more widespread for more organised response
