Chapter 16 Flashcards
Nonspecific Defenses
-protect us against any pathogen, regardless of species
NSD: First line of defense
- anatomical and physiological barriers
- physical barriers: skin, mucus membrane
- chemical barriers- secretions
- genetic barriers
NSD: Second line of defense
- cellular and chemical system
- inflammatory response, interferons, Phagocytosis, complement
NSD: third line of defense
- specialized lymphocytes (B&T cells)
- antibodies
- cytokines
- long term immunity
FLD: Physical Barriers
- Anatomical
- skin and mucous membranes
- epidermis
- hair follicles and skin glands
- keratin
- mucous membranes of digestive, urinary and respiratory tracts
- lacrimal apparatus
- ciliary escalator
- cleansing of urethra by flow of urine
- coughing, sneezing and flow of fluids with colds and allergies
- skin and mucous membranes
FLD: Chemical barriers
- sebaceous secretions
- eyelid glands
- teats and saliva- lysozyme
- acidic pH- sweat, stomach, skin, semen, vagina
FLD: Genetic barriers
- different level of sensitivity and resistance to infectious agents
- some are species specific- cat distemper
- some can cross species lines- influenza
SLD and TLD
- defines immunology
- protective cells
immunology
- study of the development of resistance to infectious agents by the body
- surveillance of the body
- recognition of foreign material
- destruction of foreign material or agent
- involve nonspecific and specific immune defense systems
- WBC or leukocytes are involved
WBC (cells important in defense)
self markers and non-self markers
- WBC recognize self markers on the host cell
- do not attack or do not respond to host cell
- WBC recognize non-self markers on the invading microbe
- attack of respond to microbe
System in defense: Reticuloendothelial (RES)
- network of connective tissue fibers (Reticulum)
- interconnects cells
- allows immune cells to bind and move outside the blood and lymphatic system
Systems in defense: Extracellular fluid (ECF)
- fills spaces surrounding tissue cells and RES
- enable immune cells to move
Systems in defense: blood
- connective tissue
- stem cells precursors->components
- components- RBC, WBC, Platelets and Plasma
Stem cells
- hematopoietic stem cells in bone marrow-> stem cels for
- neutraphils, basophils, eosinophils, monocytes
- RBC & platelets
- hematopoietic stem cells-> lymphoid stem cells
- T & B cells
WBC: Neutrophils
- present in high numbers in blood and tissue
- Phagocytizes bacteria- granules are digestive enzymes
- first to arrive during an immune response (inflammation)
WBC: Eosinophils
- present in the bone marrow and spleen
- attach to and destroy eukaryotic pathogens
- associated with inflammation and allergies
WBC: Basophils
- present in low numbers in the body
- function is similar to eosinophils
- localized basophils are called mast cells
WBC: Lymphocytes
- specific immunity
- T&B cells
- present throughout the body
WBC: Monocytes
- arganulocyte
- differentiate into macrophage (circulation and lymphatics)
- Phagocytosis
Lymphatic system
- network of vessels that extend to most areas of the body
- connected to the blood system
- provides an auxiliary route for the return of extracellular fluid to the circulatory system
- “drain off” system for inflammatory response
- contains lymphocytes, phagocytes and antibodies
- fluids
- vessels
- nodes- filter for the lymph
- spleen- filter for blood
- traps pathogens and phagocytizes pathogens
- thymus
Gut-associated lymphoid tissue (GALT)
- recognized incoming microbes from food
- supplying lymphocytes for antibody response
- ex. appendix, lacteals (lymph capillaries in sm intestine-absorb fats), Peyer’s (immune surveillance of sm intestine) patches
functions of immune system in the gut
The gut makes a huge investment in maintaining an extensive and highly active immune system. The epithelium overlying organized gut-associated lymphoid tissue (GALT) contains specialized M cells that constantly transport gut bacteria and antigens from the gut lumen into the lymphoid tissue. DC in the LP reach through epithelial cells and also sample gut bacteria. The epithelium is filled with CD8+ T cells, and the LP contains many CD4 T cells, macrophages, and IgA antibody–producing plasma cells. Potentially tissue-damaging T cell responses may be inhibited by immunosuppressive cytokines and regulatory T cells.
NSI- inflammation
-5 major systems- redness, warmth, swelling, pain and loss of function
function of inflammation
- mobilize and attract immune components to the site of injury
- aid in the repair of tissue damage
- destroy microbes and block their invasion
causes of inflammation
-heat
-physical damage
-chemicals
-microbes
major events:
-injury, vascular reactions, edema and resolution
Stages: tissue damage
- damaged cells release chemicals (histamineO
- vasoactive- affect endothelial cells of blood vessels
- chemotactic effects (chemokines)- attracts WBC
- vasoactive and chemotactic
Stages: Vasodilation
- increases blood flow to area: responsible for redness and heat
- increased permeability allows fluid from blood to enter tissue; causes edema
- pain may be caused by pressure of swelling, toxins present or nerve damage from injury
Stages: Phagocyte migration
- first responders: granulocytes especially neutrophils
- second responders: monocytes which mature into macrophage
- macrophage are larger and more phagocytic
- phagocytes stick to endothelium (inside of blood vessels) within an hour: called margination
- squeeze between the endothelial cells and enter tissue; emigration pr diapedesis (2min)
- phagocytosis begins
Stages: Edema and Pus formation
- blood clots form at site of damage and “wall” off the microbes
- pus may form in walled off area; collection of dead cells and fluid; pyogenic organisms
fever
- inhibits multiplication of temperature-sensitive microbes
- impedes bacterial nutrition by reducing access to iron
- increases metabolism and stimulates immune response
Phagocytosis
- Neutrophils and eosinophils
- macrophages- major role
- dendrocytes
Phagocytosis: Neutrophils and eosinophils
- early responders to inflammation
- neutrophils are primary components of pus
- eosinophils are primary responders to parasitic infections
Phagocytosis: Macrophage
- monocytes transform into macrophages
- scavengers
- reside in one location or drift throughout the RES
- undergo phagocytosis
- interact with B & T cells
Pattern recognition receptors (PRR)
- extend from cell
- example shows toll-like receptor
- when foreign molecule is bound -> release of chemicals that stimulate immune response
Phagocytosis: Chemotaxis
- Phagocytes migrate into area of inflammation
- attracted by chemical messengers; there is a gradient
- some microbes have signal molecules on their surface that indicate that they are “foreign”
- called PAMP’s- pathogen-associated molecular patterns
Phagocytosis: Adherence
- attach the plasma membrane of the phagocytic cell to the microbe
- attachment may be prevented by the presence of M protein of Streptococcus or presence of capsule
- opsonization-opsonins (proteins) which coat the microbe make it easier to phagocytize
Phagocytosis: Ingestion
- Pseudopods enclose the pathogen or foreign material
- form a phagosome
Phagolysosome
- lysosomes fuse with the phagosome
- other antimicrobials chemicals are released into the phagolysosome
Phagocytosis: Digestion
- within the phagolysosome
- enzyme
- nitric oxide
interferon
- produced by various immune cells in response to viral infections, microbe infections, RNA, immune products and antigens
- bind to cell surfaces and induce changes in genetic expression
Interferon: Different Classes
- interferon alpha
- product of lymphocytes and macrophages
- interferon beta
- product of fibroblasts and epithelial cells
- interferon gamma
- product of T cells
interferon: activity
- ex. virus-binds to host cell
- a signal is sent to the nucleus to synthesize (transcription and translation) interferon
- interferon is secreted
- binds to other host cells
- host cells produce antiviral proteins
- inhibit viral multiplication or translation
- not virus- specific
Complement
- consist of 26-30 blood proteins
- produced by liver hepatocytes, lymphocytes
- several pathways
- cascade reaction
- stages
Complement Pathways
- there are 3 different ways that the pathway can be “turned on”
1. Classical- activated by the presence of antibody bound to microbes
2. lectin- activated when a host serum protein binds a sugar (mannan) in the wall of fungi and other microbes
3. Alternative- activated when complement proteins bind to cell wall or surface components of microbes
Complement Stages
- initiation
- amplification and cascade
- polymerization
- membrane attack
Outcomes of Complement Activation
- cytolysis- membrane attack complex, transmembrane channels
- Opsonization C3b
- inflammation
- chemotaxis
Opsonization (outcomes of complement activation)
- C3b binds to the surface of microbes
- receptors on the phagocytes attach to the C3b
- coating of C3b enhances phagocytosis
Involvement in inflammation (Outcomes of Complement Activation)
C3a binds to mast cells, basophils and platelets to trigger the release of histamine
Chemotaxis (Outcomes of Complement Activation)
C5a attracts macrophage to the site of complement activation
