Immune System

Infectious Agent

damage/kills a host

Pathogenic Agents

cause harm to the host’s health by introducing disease

5 types of Pathogenic Agents

bacteria, viruses, fungi, protozoans

Bacteria

single cell prokaryotes that contains a membrane and cell wall; mostly harmless

Cocci

spherical bacteria

Bacilli

rodlike bacteria

Sprilla

Coiled bacteria

Virulent

bacteria that causes serious illness; may have pili, capsule, or may release toxins or damaging enzymes

Viruses

pieces of DNA or RNA in a protein shell; considered to be obligate intracellular parasites

by entering a host cell so cell can copy nucleic acid and capsid(shell)

How do viruses reproduce and kill host cells

Common Cold, Ebola, Chickenpox

most common viruses

Fungi

eukaryotic cells with membranes and cell walls that release proteolytic enzyme that induces inflammation

Fungi

causes superficial diseases such as ringworms and can infect mucosal linings

Protozoans

eukaryotic cells without a cell wall; intracellular and extracellular parasites

Malaria and Trichomoniasis

what are the two common protozoan diseases

Multicellular Parasites

nonmicroscopic organisms that take nourishment from host they live in

Prions

fragments of infectious proteins that cause disease in nervous tissue

Neutrophils, Eosinophils, Basophils

what are the 3 granulocytes

Monocytes

leukocytes that become macrophages when they leave blood and enter tissues

B-Lymphocytes, T-Lymphocytes, NK Cells

What are the 3 Lymphocytes

in body tissues

Where are most leukocytes housed?

Secondary Lymphoid Structures

T and B Lymphocytes, macrophages, dendritic cells, and NK cells housed in lymph nodes, spleen, tonsils, MALT, lymphoid nodules

epithelial layers of skin and mucosal membranes

Where are dendritic cells housed

Cytokines

small proteins that are produced by cells of both the innate and adaptive immune system; released form one cell that binds to receptors of target cells

effects of Cytokines

signaling cells, controls development and behavior of immune cells, and regulates inflammatory response

Innate Immunity

immunity (present at birth) that protects against variety of different, nonspecific substances, no prior exposure to substance necessary

Innate Immunity

type of immunity that includes barriers of skin and mucosal membranes, nonspecific cellular and molecular internal defenses; responds immediately

Adaptive Immunity

acquired/specific immunity where the response to antigen involves specific T and B lymphocytes; a particular cell responds to one specific foreign substance but not another; takes several days to take effect

Dermcidin, Lysozyme, sebum, defensins

antimicrobial substances from sweat glands and sebaceous glands of the skin

Commensal Microflora

nonpathogenic microorganism that resides on body surfaces and interferes with the attachment of potentially pathogenic organisms

when pathogens pass the first line of defense- the skin

when is the Second line of defense (nonspecific internal defenses) initiated

Neutrophils, Macrophages, and Dendritic Cells

what are the 3 phagocytic cells

Neutrophils and Macrophages

cells destroy engulfed particles by an intake vesicle fusing with lysosome to form a phaolysosome, digestive enzymes break down unwanted substances leading to respiratory burst

Respiratory Burst

process that produces reactive oxygen-containing molecules that help destroy microbes

Dendritic Cells

Cells that destroy particles and then present fragments

Antigens

what do dendritic cells present to T-Lymphocytes that is important for initiating adaptive immunity

Basophils and Mast Cells

cells that promote inflammation by releasing granules with chemicals that increase movement of fluid from blood to injured tissues

Histamine

chemotaxis chemical that increases vasodilation and capillary permeability

Heparin

chemotaxis chemical that acts as an anticoagulant

Eicosanoid

lipids released from plasma membranes of Basophils and Mast Cells that increase inflammation

Natural Killer Cells

destroy unhealthy/unwanted cells by performing immune surveillance; circulate in blood and accumulate in secondary lymphoid structures

Virus-Infected cells, Bacteria-infected cells, tumor cells, transported tissue cells

What do Natural Killer Cells destroy?

Perforin and Granzymes

Cytotoxic chemicals released by Natural Killer Cells

Perforin

cytotoxic chemical that created a transmembrane pore in unwanted cell

Granzyme

cytotoxic chemical that enters the pores and cause apoptosis of cell

Eosinophils

cells that degranulate and release enzymes and other toxic substances to attack multicellular parasites; they participate in immune responses of allergy and asthma

Antimicrobial Proteins

molecules that functions against microbes

Interferons

class of cytokines that nonspecifically interferes with spread of intracellular pathogens

IFN-a and IFN-b

interferons produced by leukocytes and virus-infected cells

IFN-g

Interferons produced by T-lymphocytes and NK cells

What do IFN-g stimulate to destroy virus-infected cells

Complement System

Group of over 30 plasma proteins, identified with a letter C and number, that works along with complement antibodies and synthesized by liver, continuously released in in active form

Classical Complement Activation

complement pathway where antibody attaches to foreign substance, then complement binds to antibody

Alternative Complement Pathway

complement pathways where complement binds to polysaccharides of bacterial or fungal cell wall

Complement

when activated, the effects are Inflammation, Opsonization, Cytolysis, Elimination of immune complexes

Complement Opsonization

when complement protein (opsonin) binds to pathogen and enhances likelihood of phagocytosis of pathogenic cells

Cytolysis

splitting of a target cell

Membrane Attack Complex (MAC)

complex that creates channel in target cell’s membrane; fluid enters and causes cell lysis

Inflammation

an immediate response to ward off unwanted substances; local nonspecific response of vascularized tissue to injury and infection; innate immunity

Events of Inflammation

1. Injured tissue, basophils, mast cells, and infectious organisms release chemicals that initiate response

2. Chemicals cause vascular changes

3. Recruitment of leukocytes

4. Delivery of plasma proteins to site

Effects of inflammation

fluid moves from blood to injured area, vasodilation, increased capillary permeability, and loss of plasma proteins

redness, heat, swelling, pain, and lack of movement

5 signs of Inflammation

8-10 days

How long does acute inflammation last

Fever (Pyrexia)

abnormal body temperature elevation of 1 degree Celsius or more over 37 degrees celsius; results from release of pyrogens from immune cells or infectious agents

Prostaglandins e2

What does the hypothalamus release after being targeted by pyrogens in event of fever

Onset, Stadium, Defervescence

What are the Fever stages in order?

Onset

stage of fever where hypothalamus stimulates less heat less and causes shivering which generates more muscle heat; temperature begins to rise

Stadium

stage of fever where elimination of harmful substances increases, microbial reproduction slows; elevated temperature is maintained

Defervescence

stage of fever when hypothalamus is no longer stimulated by pyrogens, temperature returns back to normal

seizures, denaturation of proteins, changes in metabolic pathways

What are the risks of fever?

Applying ice to inflammation

causes vasoconstriction of blood vessels, numbs area, possibly slows healing

Adaptive Immunity

immunity that involves specific lymphocyte responses to an antige; longer response time

Cell-Mediated Immunity

Adaptive immunity that involves T-Lymphocytes

Antibody-Mediated Immunity

immunity involving B-Lymphocytes, Plasma Cells, antibodies

Antigens

How are pathogens detected by lymphocytes?

Antigen

substances that bind to T-Lymphocyte or antibody; usually a protein or large polysaccharide

Foreign Antigens

Differ from human body’s molecules; bind body’s immune components

Self-antigens

the body’s own molecules'; typically do not bind immune components

Antigenic Determinant (Epitope)

the specific site on antigen recognized by immune system

Immunogen

an antigen that induces an immune repsonse

Immunogenicity

the ability to trigger response’ increases with degree of foreignness, size, complexity, or quantity

Haptens

small molecules that elicit an immune response only when attached to a large carrier protein; account for hypersensitivity reactions

TCR

antigen receptor of T-Lymphocyte

BCR

antigen receptor of B-lymphocyte

Direct

Does B-Lymphocytes make direct or indirect contact with antigen?

T-Lymphocytes

lymphocyte where antigen must be presented by another cell

Helper T- lymphocytes

CD4+ Cells that assist in cell-mediated, antibody-mediated, and innate immunity

Cytotoxic T-Lymphocytes

CD8+ Cells that release chemicals that destroy other cells

Antigen Presenting Cells

immune cells that present to both helper t-cells and cytotoxic t cells; include dendritic cells, macrophages, b-lymphocytes

Major histocompatibility Complex

group of of proteins found on the surface of cells that show immune cells what’s inside the cells; displays antigens

MHC 1

found on all nucleated cells; presents inside the cells and recognized by CD8+ Cytotoxic T Cells; destroys the cell

MHC Class 2

found on APC’s (macrophages, dendritic cells, B cells); presents outside invaders and is recognized by CD4 Helper 4 Cells; two cells are involved

Red Bone Marrow and Thymus- Primary Lymphoid Structures

Where are lymphocytes formed

Secondary Lymphoid structures

Where are lymphocytes exposed to antigen and activated?

migrate to site of infection

Effector response of T-Lymphocytes

B Lymphocytes

Lymphocytes that stay in secondary lymphoid structures to synthesize large quantities of antibodies that will be transported to infection site by blood and lymph

T-Lymphocytes

lymphocytes that originate and migrate to thymus to complete maturation, have both CD4 and CD8 proteins; possess unique TCR receptor produced randomly

Positive Selection

selects for the ability of T-cells to bind thymic epithelial cells with MHC molecules (those than can bind survive)

Negative Selection

test ability of T-lymphocytes to avoid binding self-antigens; thymic dendritic cells present self-antigens and T-cells that bind to them are destroyed

Immunocompetent

able to bind antigen and respond to it