Cells & Tissue of Immune System Flashcards
What is the normal cell count for RBCs?
5.0 x 10^6
What is the normal cell count for platelets ?
2.5 x 10^5
What is the normal cell count for Leukocytes ?
7.3 x 10^3
Describe Phagocytes
- mononuclear monocytes/macrophages
- dendritic cell
- polymorphonuclear granulocytes = neutrophils, eosinophils, basophils
What are some examples of macrophages ?
- alveolar macrophages - lung
- histiocytes - connective tissue
- mesangial cells - kidney
- microglial cells - CNS
How are macrophages differentiated ?
stem cells -> mono blast -> monocyte -> macrophage
Where can you find monocytes ?
- they circulate in the blood and migrate to tissues where they differentiate into macrophages
Describe Receptor Expression
- macrophage expresses receptors for many bacterial constituents
- bacteria binding to macrophage receptors intimate the release of cytokines & small lipid mediators of inflammation
- macrophages engulf & digest bacteria to which they bind
What are some bactericidal products from phagocytes ?
- acidification,
- toxic nitrogen oxides,
- antimicrobial peptides
How to released cytokines mediate further inflammatory responses?
- vasodilation & increased vascular permeability cause redness, heat &swelling
- inflammatory cells migrate into tissue, releasing inflammatory mediators that cause pain
What are some examples Dendritic cells
- Langerhans cells
- interstitial dendritic cells
- circulating dendritic cells
Describe Neutrophils
- polymorphonuclear cell
- 95% of circulating granulocytes
- 1st cell to arrive at the site of inflammation
- phagocytose bacteria
- circulate in blood for 7-10 hours before migrating to tissues
Describe Eosinophils
- 2-5% circulating leukocytes
- granules stain with basic eosin red
- role in removal of parasitic organisms & asthma pathology
Describe Basophils
- 0.2% of circulating leukocytes
- granules stain with acid dye methylene blue
- granules contain heparin & histamine
- plays a role in allergic response
Describe mast cells
- resides near small blood vessels
- upon activation they release histamine & other pharmacologically active substances from their granules
- play major role in allergic disease development
Describe natural killer cells
- 5-10% of blood lymphocytes
- do not express T or B cell receptors
- recognise & destroy virus-infected cells and certain tumour cells
- detection via - lack of MHC I & Fc receptors
Describe Gamma/Delta T cells
- intraepithelial cells
- part of the innate & adaptive immune system
- limited diversity
Describe B lymphocytes
- each B cell is genetically programmed to produce an antibody of unique specificity
- B cell receptor binding of antigen results in B cell differentiation into plasma cell
What are the stages of maturation for plasma cells ?
- stem cell
- pre-B cell
- immature B cell
- mature B cell
- activated B cell
- Antibody-secreting cell
Describe T lymphocytes
- 2 types = T Helper cells & Cytotoxic T lymphocytes
Describe T Helper cells
- express cytokines to coordinate the immune response
- express T cell receptor (TCR) and CD4 co-receptor
- Th1 & Th2
Describe Cytotoxic T Lymphocytes
- express T cell receptor & CD8 co-receptor
- destroy infected cells directly
Where are B lymphocytes matured ?
in the bone marrow
Where are T lymphocytes matured ?
thymus
