Chapter-22 Immune System and Body Defense Flashcards
Infectious Agents
Organisms that cause damage or possible death
Pathogenic
Infectious agents that cause harm to a host
Bacteria
Prokaryotic
Intracellular and extracellular parasites, produce enzymes, toxics
Viruses
Not cells, composed of DNA or RNA within a protein capsid, or shell.
Obligated Intracellular parasites, must enter a cell to replicate
Obligate Intracellular Parasites
Must enter a cell to reproduce or replicate
Fungi
Eukaryotic
Produce pores, release proteolytic enzymes
Exp–> yeast, molds, ringworm, diaper rash, athlete’s foot
Protozoans
Eukaryotic cells, Lack cell wall
Exp–> Malaria, toxoplasmosis, African sleeping sickness, giardiasis
Multicellular Parasites
Eukaryotic,
Live within a host, grow in size with nutrients provided by host
Exp–> tapeworms, lung flukes, liver flukes,
Prions
Small fragments of infectious proteins that cause disease in nervous tissue
Exp–> Mad cow disease, getting it by consumption of infected cow meat, make your brain spongy
Structures that House Immune System Cells:
Lymphatic Tissue
T-lymphocytes, B-lymphocytes, Macrophages, NK cells are housed in secondary lymphatic structures: spleen, tonsils, malt, lymph nodes, lymphatic nodules
Structures that House Immune System Cells:
Select Organs
Macrophages are housed in other organs, named based on location: alveolar macrophages of lungs, microglia of the brain
Either Permanent Residents=Fixed Macrophages, or Migrate through tissues=Wandering Macrophages
Structures that House Immune System Cells:
Epithelia Layers of the skin and Mucosal membranes
Dendritic Cells are located skin, mucosal membranes
Derived from monocytes like macrophages.
Dendritic cells engulf pathogens of the skin and mucosal membranes and migrate to lymph node
Structures that House Immune System Cells:
Connective tissue
Mast cells are located in the CT through the body
Structures that House Immune System Cells?
- Lymphatic Tissue
- Select Organs
- Epithelial Layers of skin and mucosal membranes
- Connective Tissue
Cytokines
Small soluble proteins produced by cells and released to bind to specific receptor of target cell
- Regulate and facilitate immune system activity
Exp–> Interlukin
Tumor Necrosis
Colony-stimulating Factor
Interferon
Innate Immunity
Born with these defenses
- 1st line of defense
- Barriers of skin, mucosal membranes that prevent entry,
- Physical barriers epithelial tissue of the dermis,
- Chemical barriers, release antimicrobial substances(cells release IgA, lysozyme sebum), biological barriers (normal flora)
Adaptive Immunity / Acquire Immunity
Involves T-lymphocyte and B-lymphocytes which respond to different foreign substances (antigens) which we are exposed during lifetime
Cellular Defenses:
Neutrophils and Macrophages
Neutrophils - 1st to arrive during inflammatory response
Macrophages - are in tissue through the body
Both engulf unwanted substance such as infectious agents and cellular debris through phagocytosis
Engulf-Lysosome+Phagosome=phagolysosome (destroys infectious agent)
Cell Defenses:
Basophils and Mast Cells
Basophils - circulate the blood
Mast cells- Reside in Ct of skin, mucosal lining and internal organs
Serve as chemotactic chemicals
Release granules during inflammatory response: Histamine, Heparin, Ecosanoids
Histamine
Increases Vasodilatation and increases capillary permeability
Heparin
Anticoagulant
Ecosanoids
Release from plasma membrane with increase inflammation
Cellular Defenses:
Natural Killer Cells
Destroy a variety of unwanted cells including viruses, bacteria, tumor cells, transplanted tissue
Release cytotoxic chemical perforin and granzyme
Perforin forms a transmembrane pore (hole) and granzyme goes in cell causing apoptosis
Immune Surveillance?
Where are they found?
NK cells patrol the body in an effort to detect unhealthy cells, Found in red bone marrow, blood, and secondary lymphatic structures
Eosinophils
- Target parasites by degranulation and releasing enzymes and other substances lethal to parasites.
- Release proteins that form transmembrane pore to destroy multicellular organisms.
- Participate in immune responses: allergies, asthma
Antimicrobial Proteins
Components of innate immune system that are against microbes
Interferons (IFN’s)
Are cytokines
- work agains the spread of any viral infection
- Infected cells prevent the spread of the virus, by realizing IFN.
- IFN bind to neighboring cell to prevent them from getting infected, stimulates NK cells and macrophages to destroy virus infected cells
Complement System
Antimicrobial group of substances of innate immunity Serve to protect body against pathogens -Opsonization - Inflammation - Cytolysis - Elimination of immune complexes
Classical Pathway
Complement proteins bind to an antibody that has previously attached to a foreign substance
Alternative Pathway
Surface of polysaccharides of certain bacterial and fungal cell walls bind directly with a complement protein
Complement Sysptem:
Opsonization
Protein (complement) binds to bacteria or other cell type (to be identified) so ti can be phagocitized.
Complement System:
Inflammation
Complement increases inflammatory response by activation of mast cells and basophils and by attracting neutrophils and macrophages
Complement System:
Cytolysis
Many complement components trigger direct killing. Form a protein channel plasma membrane of target cell MAC, (Membrane Attach Complex) causing the cell to lyse (a lot of fluid inside cell).
Complement System:
Elimination of immune complexes
Complements bind antigen-antibody to erythrocytes to be transported to the liver and spleen. Where they are striped by macrophages, erythrocyte continue to circulate the blood
Inflammation / Inflammatory Response
Nonspecific even that occurs in vascularized tissue against a variety of injury-causing stimuli.
Events of Inflammation
- Release of chemicals from injured cells, mast cells, basophils, and infectious organisms. Include: Histamine, prostaglandin, leukotrienes, chemotactic factors.
- Chemicals trigger vascular changes: Increase capillary permeability and capillary endothelium to provide Cell-Adhesion Molecules (CAMs)
- Leukocytes go to infected tissue by:
a) Margination - leukocytes CAMs attach to capillary endothelium CAMs.
b) Diapedesis is where cells squeeze out of the vessel wall cells
c) Chemotaxis is migration of leukocytes along chemical gradient.
They are attracted by the chemicals released from damage cells, dead, or invading pathogen (chemical gradient) - Plasma proteins go int injured area (immunoglobulins, complement, clotting proteins and kinins.
-clotting proteins lead to formation of a clot that walls of microbes and prevents them from spreading into the blood and tissues
-Kinins (bradykinin) increase capillary permeability and stimulate pain receptors (stimulus for causing pain associated with inflammation) - Exudate
Exudate
Materials like: increase fluid, protein, and immune cells leave the capillaries and then enter the interstitial space of the tissue. Which delivers cells and substance needed to eliminate injurious agent and promote healing
Cardinal Signs of Inflammation
- Redness due to increase blood flow
- Heat due to increase blood flow and increase metabolic rate with in the area
- Swelling result from increase fluid loss from capillaries into the interstitial space
- Pain due to accumulation of interstitial fluid, and chemical irritation by kinins, prostaglandins,and substance release from microbes.
- Loss of function due to pain and swelling (more severe cases)
Acute Inflammation Response
inflammatory response last no longer 8-10 days
Chronic inflammation
Inflammation occurs for more than 2 weeks
Fever (pyrexia)
Abnormal elevation of body temperature.
Pyrogens
Interleukin 1, interferons, toxins produced by infections agents, response trauma, drug reaction or brain tumors.
Events of Fever?
Pyrogens are release and circulate the blood, they target the hypothalamus and cause the release of prostaglandin E2.
- Onset - Hypothalamus stimulates blood vessels in the dermis of the skin to vasoconstrictor to decrease heat loss. Person shrivers to increase heat production making body temp rise
- Stadium - Elevated temperature is maintained. Metabolic rate increase to have more heat. Liver and spleen bind to zinc and iron (which are minerals needed for microbes) to slow microbial reproduction.
- Defervenscence- temperature returns back to normal, the hypothalamus is no longer stimulated by pyrogens, prostaglandins release decreases. Hypothalamus stimulates vasodilatation of blood vessels and the skin and sweating to release heat
Immune Response
Lymphocytes form and what they secret
Cell-Mediated Immunity
Immune response involving T-lymphocytes
Humoral Immunity
Immune response involving B-lymphocytes that develop into plasma cells to synthesize and release antibodies
Antigen
substance that binds to a components of adaptive immunity
Foreign Antigens
non-self antigen bind with in the body immune components, different than human body’s molecules
Self antigens
Body molecules, that do not bind to body immune components
Autoimmune Disorder
own immune system reacting to self-antigens, as if they where foreeing
Antigenic Determinant / Epitope
Specific site of the antigen molecule that is recognized by components of the immune system
Immunogen
Antigen that induces an immune response
Immunogenicity
Immunogen ability to cause an immune response
Haptens
Too small to functions as an antigen alone, need to attach to a carrier molecule in the host, and become antigenic and trigger and immune response
Receptor complex
T-lymphocytes and B-lymphocytes receptors, Different and separate proteins, about 100,00 receptor complexes per cell
TCR (T-cell receptor)
antigen receptor (portion of a receptor complex) of T-lymphocytes
BCR (B-cell receptor)
antigen receptor of B-lymphocytes
Helper T-lymphocytes / CD4
Activate B-lymphocytes, contain CD4 proteins in the plasma membrane
Cytotoxic T-lymphocytes / CD8 cells
Release chemicals that are toxic to cells, resulting in destruction, Contain CD8 plasma membrane protein
Antigen Presentation
Presenting of antigen on plasma surfaces, so T-lymphocytes can see the antigen
Antigen Presenting Cell
Communicate the presence of antigen to T-lymphocyes and B-lymphocytes
Major Histocompatibility Complex
Specialized transmembrane protein where antigen is attached
MHC class I molecule
Are glycoproteins on nucleated cells, where antigen attaches too.
Synthesized of MHC I?
- Synthesized by RER, peptide fragments bind to MHC class I molecules
- They are transported in vesicles through he endomembrane system, through the Golgi apparatus to the plasma membrane.
- Vesicle fuses to plasma membrane and MHC class I molecules and antigen or self antigen are displayed within the plasma membrane
Major Histocompatibility II molecule
Found on antigen presenting cells -Dendritic cells, macrophages, B-lymphocytes (all display both MHC class I, and II)
MHC class II Molecule Synthesize
- MHC class II is synthesized in Rough Endo Plasmic Reticulum then its
- Packed into vesicles and shipped to Golgi Apparatus
- Exogenous antigen is phagositozed by the cell. A phagosome (vesicle) is formed, then meets with lysosome to form a phagolysosome. Substance is digested into fragments
- Vesicles containing MHC II is combined with vesicles containing the antigen
- MHC class II molecule and foreign antigen are displayed with in the plasma membrane
Provides means of communication specially to Helper T-lymphocytes
Organ Transplant
Transfer of an organ from one individual to another. Before transplant donor and recipient are tested for major histocompatibility Complex antigens and the ABO blood group antigens.
Because MHC molecules can be detected by immune system as foreign and cause rejection.
Exogenous Antigen
Pathogens, cellular debris, or other potential harmful substance located outside of cell, and are engulf by APC
Activation of Helper T-lymphocytes:
First Response
- First Stimulation - Physical contact with APC and Helper T-lymphocyte. Antigen was engulf and is displaying on APC membrane surface with MHC class II molecule
- TCR of T-lymphocytes bind to peptide fragment (antigen)presented with an MHC class I molecule of the APC.
- Stabilizing CD4 molecules of the helper T-lymphocytes binding to other regions of the MHC class II molecule.
Activation of T-Lymphocytes
Second Stimulation
- Helper T-lymphocytes begin to secrete cytokine Interleukin 2 (IL-2) occurs within 24 hrs.
- T-lymphocytes poliferate to form a clone of helper T-lymphocytes (the cells produced are: helper T-lymphocytes that continue to produce IL2, and memory helper T-lymphocytes for subsequent encounter with the specific antigen
Activation of Cytotoxic T-Lymphocytes
First Stimulation
- CD8 binds with MHC class I molecule of infected cell, TCR interacts with antigen within MHC class I molecule
Activation of Cytotoxic T-lymphocytes
Second Stimulation
IL 2 of helper T-lymphocytes bind to cytotoxic T-lymphocytes, acts as a paracrine hormone to stimulate the cytotoxic T-lymphocytes
Activation of B-Lymphocytes
First Stimulation
Antigen bind to BCR and antigen cross-links BCR’s. B-lymphocytes engulfs, processes and presents antigen to helper T-lymphocytes that recognizes the antigen.
Activation of B-lymphocytes
Second Stimulation
Activated helper T-lymphocyte releases IL4, to stimulate B-lymphocytes
Activation of B-lymphocytes causes proliferation and differentiate into plasma cells that produce antibodies, and the remainder become memory B-lymphocytes that are activated upon reexposure of the same antigen
Lymphocyte Recirculation
B and T-lymphocytes circulate through the blood and lymph every several days
Provides delivery of different lymphocytes to secondary lymphatic structures, making it more likely that a lymphocyte will encounter its antigen, if present.
Effector Response
Activate lymphocytes use to help eliminate the antigen
Antibody Titer
Circulating blood concentration of antibody against a specific antigen
Antibody Immunoglobulin
Tags the antigen, so it can be eliminated
Antibody Monomer
4 polypeptide chains are held together by disulfide bonds
Variable Regions
Antigen binding site, attaches to a specific antigen.
Binds to antigen through weak intermolecular force, including hydrogen bonds, electrostatic interactions, van der Waal forces and hydrophobic interactions
Constant Region
Contains FC region,, portion of the antibody that determines the biological functions of the antibody.
Actions of Antibodies:
Neutralization
Antibody covers an antigenic determinant of a pathogen
Antibody attaches to pathogen binding cell receptor to prevent it from attaching to a cell
Action of Antibodies:
Agglutination
Antibody cross-links antigens of foreign cells, causing them to clump
Actions of Antibodies:
Percipitation
Antibody can cross-ling soluble, circulating antigen such as viral particles (not whole cells) to form an antigen-antibody complex. Wait fro phagocytic cells to be engulfed and eliminated
Fc Region:
Complement Fixation
Fc region of some classes of antibodies can bind to complement protein
Fc Region
Opsonization
Fc region of antibody binds to receptors of phagocytic cells triggering phagocytosis
Fc Region
Activation of NK cells
Fc region of antibody binds to a NK cell, triggering the release of cytotoxic chemicals called —Antibody-dependent cell-mediated cytotoxicity (ADCC)
IgG
Major class of immunoglobulins
Location: Body Fluids–>blood, lymph nodes cerebral spinal fluid, serous fluid, peritoneal fluid
Function: Neutralization(virus, bacteria, toxins)
- agglutination, precipitation, complement activation, opsonization, natural killer cell activation
_Passive immunity crosses the placenta, component of breast milk
“I Gave Good milk”
IgM
Location, Function,
B-lymphocyte receptor, responsible for rejection blood transfusion
Location: found in blood
Action: Neutralization, agglutination, Complement binding
