Immunology Flashcards
What are the key features of the Immune System?
- Able to specifically identify non-self and danger signals.
- Able to modify the response to deal with different pathogens.
- Able to actively promote tissue repair and healing.
- Able to remember any pathogen it encounters. (Immunological Memory)
Name some constitutive barriers to infection?
- Skin.
- Mucous.
- Commensal Bacteria.
Describe the skin barrier.
- Physical barrier: multi-layered, renewal and replacement.
- Physiological factors: low pH 5.5, low O2 tension.
- Sebaceous glands: secrete hydrophobic oils, lysozyme, ammonia, antimicrobial peptides.
Describe the mucous barrier.
- Mucous membranes: Secrete mucous where cavities come into contact with the environment.
- Physical barrier: traps invading barriers.
- Secretory IgA: prevents Bac and Virus attaching and penetrating epithelial cells.
- Contains enzymes: lysozymes, defensins and antimicrobial peptides directly kill. Lactoferrin starve bacteria of iron.
- Cillia trap and physically remove pathogens.
Describe the commensal bacteria.
- 100 trillion (10^14) normally reside at epithelial surfaces.
- Produce Bactercidins influencing other bacteria.
- Reduction in pH of large bowel.
- Competition for essential nutrients,
- Production of anti-microbial short-chain fatty acids.
- Synthesis of vitamins K and B12.
How important are commensal bacteria?
- Eradication of normal flora with broad-spectrum antibiotics commonly result in infection.
- Organisms rapidly colonize an undefended ecological niche.
How are constitutive barriers breached during health care?
- Insertion of intravenous lines, catheters, nasogastric tubes.
- Antibiotics.
- Anti-acids, nasal decongestants, anti-bacterial wipes.
Name the Major Components of the immune system.
- Cells: Leukocytes, White blood cells.
- Soluble factors: Humoral factors.
Name Phagocytes.
- Neutrophils.
- Monocytes and macrophages.
- Dendritic cells.
Name Lymphocytes.
- T cells.
- B cells.
- Natural killer cells.
Name other cells.
Mast cells, Eosinophils and Basophils.
Name Humoral factors.
- Antibodies.
- Complement system proteins.
- Cytokines.
- Acute phase proteins.
Cytokines.
- Diverse collection of small proteins and peptides produced in response to infection, inflammation and damage.
- Modulate behaviour of cells so play a key role in coordinating the immune system.
- Multiples overlapping functions.
- Short half-life.
- Local or systemic.
Antibodies.
- Protein produced in response to specific antigen.
- Produced by antigen-activated B Cells.
- Defend against pathogens, viruses and toxins.
T cells and B cells.
- Mature cells circulate through the blood, lymph, and secondary lymphoid tissues.
- Inactive until meet pathogen/antigen.
- Some are very long lived. (memory T and B).
B Lymphocytes.
- Responsible for production and secretion of antibodies to defend against pathogens.
T Lymphocytes.
- Helper T cells: Key regulators of immune system.
- Cytotoxic T cells: Kill virally infected body cells.
Natural Killer cells.
- Large granular lymphocytes.
- Can detect and kill tumour cells and virally infected cells.
- Can kill antibody-bound cells/pathogens.
Mast cells.
- Reside in tissues and protect mucosal surfaces.
Basophils, Eosinophils.
- Circulate in blood.
- Recruited to sites of infection by inflammatory signals.
Mast, Basophils and Eosinophils.
- Highly granular.
- Release Histamine, Heparin, and pro-inflammatory cytokines.
- Defense against pathogens that cannot be phagocytosed. (worms)
- Key role in mediating allergic responses.
Complement system.
- Approx. 30 proteins.
- Produced in Liver.
- Circulate in blood as inactive precursors.
- Enter infected/inflamed tissues.
- Enzymatically cleave and activate more in biological cascade.
Monocytes, Macrophages, and Neutrophils.
- Phagocytes.
- Ingest and clear debris from body.
- Important source of Cytokines.
Monocytes.
- Circulate in the blood.
- Migrate to peripheral tissues and differentiate into macrophages.
Macrophages.
- Long-lived tissue resident in phagocytes.
- Kupffer = Liver.
- Alveolar = Lung.
- Mesangial = Kidney.
- Microglial = Nervous.
- Limit inflammation, tissue repair, antigen presentation.
Neutrophils.
- Phagocytic cells that circulate in the blood.
Rapidly recruited into inflamed, damaged, and infected tissues.
Dendritic cells.
- Present in peripheral tissues in an immature state.
- Phagocytose antigens.
- Mature and migrate into secondary lymphoid tissues where they play a key role in antigen presentation.
Comparing dendritic, macrophage, and neutrophils.
- Neutrophils: Complete destruction of proteins are seen.
- Dendritic: Partially degraded for antigen presentation and stimulation of adaptive response.
- Macrophages: Neutral = Clearance of dead host cells.
Activated = phagocytosis of pathogens.
Repair = reduced activity, produce pro-inflammatory cytokines.
Primary Lymphoid Tissues.
- Sites of Leukocyte development.
Where do Lymphocytes mature and circulate?
- Mature: bone marrow or thymus.
- Circulate: between blood, secondary peripheral lymphoid tissues and lymph.
What are the immunological precursors found in bone marrow?
- Hematopoietic stem cells.
Secondary Lymphoid Tissues.
- Sites where T cells and B cells become activated by antigen. (initiates adaptive immunity).
Name secondary lymphoid tissues.
- Lymph Nodes: imp stations for monitoring tissues infections.
- Spleen: imp in monitoring blood-borne infections.
- Mucosal: associated lymphoid tissues.
Lymphatic system.
- System of vessels draining lymph fluid from body tissues.
Lymph.
- Derived from blood plasma in tissues.
- Drains back to blood via lymphatic vessels and the right subclavian vein.
Lymph Nodes.
- Positioned along lymph vessels to monitor the lymph for signs of infection.
Lymphoedema.
- Lymphatic obstruction.
- Inherited, cancer treatment and parasitic infections.
- At increased risk of infection.
Immune system compromised of two arms.
- Innate Immune.
- Adaptive Immune.
Innate Immune system.
- Acute inflammation.
- Macrophages.
- Mast cells.
- NK cells.
- Neutrophils.
- Complement.
- Leads to Dendritic cells.
Adaptive Immune system.
- B cells, Antibodies.
- T cells.
- D cells and macrophages present antigens.
- Activates T cells.
- T cells produce cytokines that help phagocytes.
- B cells produce antibodies that coat bacteria and help phagocytes.
Innate system response.
- Rapid response (mins-hrs).
- Generic biological response is produced in response to many pathogens.
Adaptive system response.
- Slow response (days).
- A unique response for every pathogen.
- Mediated by T and B cells.
- Responsible for immunological memory.
