Immune System Part 1 Flashcards
Primary Lymphoid Tissues
Development of immune cells
- Bone Marrow: maturation of B cells
- Thymus Gland: maturation of T cells
- Size and activity peaks in adolescence and may disappear in old age
Secondary Lymphoid Tissues
Site rich in active immune cells
-Can be encapsulated or diffuse
Encapsulated Secondary lymphoid tissues
Surrounded by connective tissue
Spleen-filters damaged cells and microorganisms from blood
Lymph Nodes- filter fluid captured from interstitial spaces
Diffuse Secondary lymphoid tissues
Aggregation of immune cells, not encapsulated
-Tonsils-filter out inhaled/ingested pathogens
Mucosa associated lymphoid tissue, gut associated lymphoid tissue (GALT)
Main Components of Pathogen Defense (3)
1 . Physical and chem barriers (skin, tears, saliva, etc)
- Innate Immunity
- Adaptive Immunity
Innate Immunity
Non-specific defenses, respond to pathogens and tissue damage
Adaptive Immunity
Specific defenses, recognize and respond to specific pathogens
Jobs of Complement Cascade
Identify bacteria
Activate additional immune cells
Promote clearance of dead cells or antibody complexes
Activation of adaptive immune system via APC
Dendritic cells and macrophages
- Toll-like receptors on APC recognize foreign molecule
- Macrophages also respond to phosphatidylserine, a signal for apoptotic cells
Inflammatory response
occurs when there is damage or invasion which has penetrated the skin
- 4 signs: rubor, tumor, calor (heat), dolor (pain)
- Attracts immune cells and chem mediators
- Produce phys barrier to prevent spread of infection
- promote tissue repair (increased blood flow)
Main jobs of Innate Immunity
- Recruits immune cells to sites of infection and inflammation (produce cytokines)
- Activation of complement cascade
- Identification and removal of foreign substances by WBCs
- Activation of adaptive immune system (via APC)
- Inflammatory response
Inflammatory Response Molecules (5)
- Acute phase proteins
- Histamine
- Interleukins
- Bradykinin
- Complement
Acute Phase Proteins
Immediate response proteins in plasma
- Many produced by liver
- Opsonins that coat pathogens, antiproteases, that prevent tissue damage
- Persist long-term in chronic inflammation (atherosclerosis)
- Inflammatory response molecule
Histamine
Released by mast cells and basophils in response to cytokines
- initiation of inflammation
- causes dilation and leakiness of capillaries
Interleukins
Specific class of cytokines
- IL-1 secreted by macrophages and other immune cells
- Alters blood vessel endothelium to allow WBC to site
- Stimulate liver to make acute phase proteins
- Induces fever
- Stimulate cytokine and endocrine secretion
Bradykinin
Vasodilator and stimulator of pain receptors
Inflammatory Response Sequence
- Antibodies (produced by B lymphocytes) bind to antigens of pathogen to mark pathogen for phagocytosis
- Mast cells in the area respond to the infection and signal by releasing heparin, histamine, prostaglandins, leukotrienes
- Neurophils are the 1st to arrive and kill the pathogen and signal for other immune cells to come
- Monocytes arrive later and eat dead neutrophils and pathogen and debris
Signals released by mast cells at site of infection
- Heparin: anticoagulant
- Histamine: bronchiolar constriction, vasodilation and increase in vascular permeability
- Prostaglandins -lead to pain and fever (IL1)
- Leukotrienes: bronchiolar constriction, vasoconstriction, increase in vascular permeability
Complement System
- More than 25 plasma proteins
- Create holes in bacteria cell walls
- Mark bacteria for phagocytosis
- Stimulate mast cells to release histamine
Steps of Complement System Activation (3)
- Recognition: C1 becomes activated by antibodies
- Activation: hydrolytic activation cascade of C4, C2, and C3
- Attack: C5-C9 organize into the pores w/in pathogen membrane (membrane attack complex)
Alternate Pathway
Slower activation of complement system based on unique carbs on pathogen surgace
-Leads to common activation of C3
Classical Pathway
Activation of complement system
- Initiated by antibody opsonization on pathogens
- Begins w/ C1
C3a and C5b in complement cascade
Stimulate histamine release
C5b in complement cascade
Chemokin trail for neutrophils and monocytes/macrophages
Natural Killer Cells
Destroy viral infected and cancer cells
- Induce apoptosis
- Secrete interferons
Interferon
Can protect cells from viral infections
- Interferon alpha and beta stimulate production of antiviral proteins
- Interferon gamma stimulate macrophages and other immune cells
Pyrogens
Trigger fever
-Can be exogenous (released by pathogens) or endogenous (released by immune cells)
Benefits of fever
- Unbearable environment for some pathogens
- Stimulate WBC proliferation
- Enhanced leukocyte phagocytosis
- Increase proliferation of T cells
- Enhanced activity of interferon
Reye Syndrome
Neurological disorder triggered by a viral infection
