ACE2034: Lecture 2

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  • Created by: LMoney
  • Created on: 10-05-14 12:45
what are the 5 stages of response to infection?
1) awareness of infection 2) immediate response to infection 3) delayed response to infection 4) destruction or elimination of pathogen or neutralisation of threat posed by pathogens 4) provision of immunity
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which cells recognise pathogens?
1) macrophages (stationed at strategic places in body; secretory cells) 2) neutrophils
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what are the 4 stages of phagocytosis?
1) attachment 2) ingestion 3) killing 4) degradation
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what carries out the degradation?
proteolytic enzymes
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what is Haematopoiesis?
the process of specialisation of Haematopoietic stem cells (which reside in the bone marrow) to give rise to all of the different mature blood cell types and tissues
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what are the 2 initial types of cell that Haematopoietic stem cells give rise to?
1) lymphoid stem cell 2) myeloid stem cell
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what do macrophages do after the initial stage of recognition?
Produce 1) prostagladins 2) PAF (platelet activation factor) 3) cytokines
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what are cytokines?
large number of smallish proteins serving a hormone-like function enabling cells to communicate with each other
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what size are cytokines usually?
usually less than 20kDa
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do cytokines act locally or do they have a target further away?
Cytokines do not usually act in an endocrine manner, rather they act locally
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they are produced by cells in a particular tissue and act on cells in that tissue, what kind of action is this?
paracrine and autocrine action
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after recognition and release of prostaglandins, PAF (platelet activation factor) and cytokines, what else does a macrophage release?
IL-1, IL-8 and TNF-a
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where do TNF-a, PAF and prostaglandins act?
on the endothelium to increase vascular permeability
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what does PAF do?
cause platelets to release histamine
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IL-1 and TNF-a activate endothelial cells lining the blood vessels, what effect does this have?
allows neutrophils to leave the bloodstream
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what do neutrophils and macrophages do?
ingest and kill bacteria and other micro-organisms
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what is chemotaxis?
movement of an organism in response to a chemical stimulus
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IL-8 is chemotactic for what?
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what are mast cells?
Type of white blood cells similar to basophils
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what happens when mast cells are activated?
they release the content of their granules having an effect on vasodilation and increasing vascular permeability, which in turn attract the neutrophils
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in the clotting system, what happens when fibrinogen is cleaved?
generates fibrin threads which form blood clots
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Fibrinopeptides are chemotactic for what?
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what is the complement system?
The system of Plasma proteins which play many roles in resistance to infection
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what is the acute phase response?
short lived and confined to the area of tissue damage
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what happens if pathogens not eliminated?
there is a rise in the concentration of macrophage-derived cytokines in the plasma, which can affect brain and liver cells
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what are the acute-phase proteins?
Serve different physiological functions for the immune system. Some act to destroy or inhibit growth of microbes, e.g., C-reactive protein, mannose-binding protein, complement factors, ferritin, ceruloplasmin, Serum amyloid A and haptoglobin
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which positive acute-phase proteins give negative feedback on the inflammatory response?
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what are opsonins?
proteins that bind to molecules no the surface of microbes and to specific receptors on phagocytes- binding of the opsonin to the phagocyte receptor activates phagocytosis
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what are interferons?
type of cytokine
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what are the 3 types of interferon?
IFN-a; IFN-β ; IFN-y
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where are IFN-a and IFN-B produced?
by Macrophages, fibroblasts, lymphocytes, endothelial cells and epithelial cells
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what is IFN-y produced by?
lymphocytes and natural killer cells
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what are the Functions of IFNs?
Inhibition of viral replication, activation of macrophages and natural killer cells
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what are natural killer cells?
Represent 1-5% of the white blood cells, kill other cells especially tumour cells (people without NK cells are more susceptible to herpes viruses)
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what play a crucial role in NK activation?
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what is their role in inflammation?
they enter sites of inflammation, stimulated by IL-12 produced by macrophages in return they produce IFN-y which activates macrophages
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what does it mean if a cell is cytotoxic?
the quality of being toxic to cells
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how are NK cells cytotoxic?
granules in cytoplasm contain protein and proteases
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how do they kill pathogen cells?
by contact or by antibody-mediation
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which cells recognise pathogens?


1) macrophages (stationed at strategic places in body; secretory cells) 2) neutrophils

Card 3


what are the 4 stages of phagocytosis?


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Card 4


what carries out the degradation?


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Card 5


what is Haematopoiesis?


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