Chapter 21 Immune System Flashcards
Which of the following contributes to the flow of lymph through lymphatic vessels
The pumping of the heart
The milking action of skeletal muscle contraction*
Pressure changes in the thorax that result from breathing*
Both b and c****
All of the above
The thymus is important for ____
- T lymphocyte maturation*
- removal of foreign antigens
- B lymphocyte maturation
- secretion of hormones that promote B lymphocyte immunocompetence
Areas of the spleen that contain large aggregation of lymphocytes are known as
- peyers patches
- adenoids
- white pulp*
- red pulp
- lymph nodes
Immunity
- bodys defense against invaders
- resistance to disease
- immune system has two intrinsic systems:
- innate
- adaptive
innate immunity
- nonspecific defense system
- born with
- 1st line of defense- surface barriers- skin, mucous membranes
- 2nd line of defense- internal defenses
adaptive immunity
- specific defense system
- active
- 3rd line of defense:
- humoral immunity
- cellular immunity
Internal defenses
- 2nd line of innate defense
- cells and chemicals
- necessary if microorganisms invade deeper tissues
- phagocytes
- Natural Killer (NK) cells
- inflammation- inflammatory response (macrophages, mast cells, WBCs, and inflammatory chemicals)
- antimicrobial proteins (interferons and complement proteins)
- fever
Surface barriers
- 1st line of innate defense
- skin (keratin)- physical barrier to most microorganisms
- mucosae provide similar mechanical barriers
- mucous membranes
- hair
- protective chemicals inhibit or destroy microorganisms
- skin acidity
- lipids in sebum and dermcidin in sweat- toxic
- stomach acids
- lysozyme of saliva and lacrimal fluid
- mucus- traps microorgansisms
humoral and cellular immunity
- 3rd line of defense
- humoral immunity- B cells
- cellular immunity- T cells
phagocytes: neutrophils and macrophages (and eosinophil)
- neutrophils- most common
- macrophages- develop from monocytes to become the chief phagocytic cells
- phagocyte mobilization:
- leukocytosis
- margination
- diapedesis
- chemotaxis
phagocyte mobilization
- leukocytosis- neutrophils enter blood from bone marrow
- margination- neutrophils cling to capillary wall
- diapedesis- neutrophils flatten and squeeze out of capillaries
- chemotaxis- neutrophils follow chemical trail
- innate defense -> internal defense
- inflammatory chemicals diffusing from the inflamed site act as chemotactic agents
Phagocytosis: Step 1: Adherence of phagocyte to pathogen
- facilitated by OPSONIZATION (to make tasty)- coating of pathogen by complement proteins or antibodies -> attracts the phagocyte
- destruction of pathogens:
- acidification and digestion by lysosomal enzymes
- respiratory burst- release of cell killing free radicals
Natural Killer (NK) cells
- large granular lymphocytes
- target cells that lack self cell-surface receptors, look for ABNORMAL cells
- induce apoptosis (suicide) in cancer cells and virus- infected cells before immune system is activated
- secrete potent chemicals that enhance the inflammatory response (positive feedback)
Inflammatory Response
- triggered whenever body tissues are injured or infected
- prevents the spread of damaged agents
- cardinal signs of acute inflammation:
- redness
- heat
- swelling
- pain
- (sometimes) 5. impairment of function
Benefits of inflammation
- dilutes harmful substances
- brings in useful substances
- disposes of debris
- pain immobilizes
- prevent spread of damaging agents
steps of inflammatory response
- tissue injury
- release of different factors and chemicals -> initiate inflammatory response (histamine, complement proteins, prostaglandins)
- vasodilation of arteries -> local hyperemia -> heat -> redness -> increased metabolic rate of cells -> increased healing
- increased capillary permeability -> leak fluid -> pain -> swelling -> possible temporary limitation of joint movement -> increased healing
- neutrophils, monocytes etc. released
- leukocytosis factors
antimicrobial proteins
- interferons (IFNs) and complement proteins
- attack microorganisms directly
- hinder microorganisms ability to reproduce
interferons
- interfere with viral replication
- viral infected cells are activated to secrete IFNs
- IFNs enter neighboring cells
- neighboring cells produce antiviral proteins that block viral reproduction
- activate macrophages and mobilize NK cells
- virus enters cell
- interferon genes switch on
- cells produces interferon molecules
- interferon binding stimulates cell to turn on genes for antiviral proteins
- antiviral proteins block viral reproduction
complement activation
- activated complement
- enhances inflammation
- promotes phagocytosis (opsonization)
- causes cell lysis
- formation of a membrane attack complex (MAC)
- MAC causes cell lysis by inducing a massive influx of water by making a hole
- complement enhances the effectiveness of both the innate and adaptive defenses
- complement system is major mechanisms for destroying foreign substances
fever
- systemic response to invading microorganisms
- leukocytes and macrophages secrete pyrogens
- pyrogens reset the body’s thermostat upward (hypothalamus)
- high fevers are dangerous because heat denatures enzymes
- benefits of moderate fever -> increases metabolic rate, which speeds up repair
inflammation ________
- is caused by bacterial activity to enhance the spread of disease
- is caused by viral activity to enhance the spread of the disease
- slows the healing process with swelling that can impair bodily function
- brings more leukocytes to the sight of infection***
interferons __________
- are virus-specific, so that an interferon produced against one virus could not protect cells against another virus
- act by increasing the rate of cell division
- interfere with viral replication within cells*
- are routinely used in nasal sprays for the common cold
adaptive defenses
- the adaptive immune (specific defense) system - immunity to one disease doesn’t protect you against a different disease
- protects against infectious agents and abnormal body cells
- amplifies the inflammatory response
- activated complement
- specific
- systemic
- has memory
- HUMORAL
- CELLULAR
adaptive immune system: Humoral
- antibody mediated
- immunity (“humors” are fluids) - B cells!
Adaptive immune response- Cellular
- cell-mediated immunity
- T cells
antigens- Antibody Generator
- antigens are the targets of immune response
- most are large, complex molecules not normally found in the body (nonself)
complete antigens
- large molecules
- immunogenicity- can stimulate specific lymphocytes to multiply
- reactivity- ability to react with these lymphocytes and antibodies
incomplete antigens- Haptens
- small molecules
- are not immunogenic
- combine with body’s own proteins and cause an attack that is harmful not protective (animal dander, detergents)
- dont react with our immune system -> combine with our own proteins
Antigenic Determinants
- certain parts of an entire antigen that are immunogenic
- antibodies and lymphocyte receptors bind to them
- large, chemically simple molecules (e.g. plastics) have little or no immunogenicity
Self-Antigens: MHC proteins
- protein molecules (self-antigens) on the surface of all your cells
- these are the tags that label your cells as part of your cells -> NK cells attack if lacking!
- self antigens are not foreign to you
- antigenic to others in transfusions or grafts
- MHC (major histocompatibility complex) proteins
- presence of this protein allows immune system to differentiate btw our cells and foreigners
- MHC are cells’ identity markers
cells of the adaptive immune system: lymphocytes
- two types of lymphocytes: B and T lymphocytes
- B cells- humoral immunity
- T cells- cell-mediated immunity
- react to only one type of antigenic determinant
- training process is very selective -> only 2% survive
-antigen-presenting cells (APCs)
antigen-presenting cells (APCs)
- do not respond to specific antigens
- play essential auxiliary roles in immunity
- dendritic cells
- macrophages
- B lymphocytes
- engulf antigens
- present fragments of antigens to be recognized by T cells -> like signal flags on their surface
B cells
- form in bone marrow
- mature in RED bone marrow
- seed the secondary lymphoid organs and circulate through blood and lymph
- antigen receptors bind to antigen -> activation
- multiplies and differentiates
- memory cells or effector cells form