immune system -exam3

what are the major functions of the immune system

• Defend against invading pathogens such as bacteria and viruses

• remove worn-out cells and damaged tissue

• immune surveillance

where are immune cells produced

undifferentiated pluripotent stem cells in red bone marrow

what is innate immunity

a rapid, immediate, nonspecific defense that responds to foreign material or tissue damage. It does not target one particular pathogen

what is adaptive immunity

A specific defense that recognizes and targets particular antigens. It involves B and T cells and can produce memory cells for future encounters

what do cells of the innate immune system recognize

• pathogen associated molecular patterns

• damage associated molecular patterns

what do cells of the adaptive immune system recognize

specific antigens associated with particular foreign substances or pathogens, allowing a targeted immune response

what do immune cells recognize and respond to

antigens, pathogen-associated molecular patterns and signals of tissue damage

Cells of the innate immune system

• neutrophils

• eosinophils

• basophils

• monocytes

• macorphages

• natural killer

• mast

Neutrophils

• engulf and destroy bacteria

• contain granules with antimicrobial proteins

• an increase neutrophil count can indicate a bacterial infection

Eosinophils

• help defend against parasitic infections and participate in allergic conditions

• attach to parasites and release substances to kill them

• participate in allergic conditions

• an increased eosinophil count can indicate an allergic condition

basophils

• release histamine and store heparin

• histamine contributes to allegric reactions and inflammation

• heparin helps with the removal of fat particles from the blood

monocytes

• enter tissues and mature into macrophages

• act as professional phagocytes

• engulf pathogens and release cytokines that help coordinate inflammation

macorphages

engulf pathogens and contribute to inflammation

natural killer cells

destroy virus infected cells and cancer cells

mast cells

release histamine during inflammation

what is a granulocyte

a white blood cell containing granules with substances that help defend the body

what are the three types of granulocytes

• neutrophils

• eosinophils

• basophils

what is inflammtion

a nonspecific response to foreign invasion or tissue damage

what are some of the physiological functions of the inflammatory response

• Recruiting immune cells to the site of injury or infection

• increasing local blood flow and capillary permeability

• helping contain the affected area

• destroying invading pathogens

• removing damaged material

• promoting tissue repair

what are the basic steps of an inflammatory response in the case of tissue damage with the introduction of bacteria

1) tissue damage occurs: a break in the skin allows bacteria to enter and reproduce at the wound site

2) macrophages respond: resident macrophages engulf pathogens and release chemokines and other cytokines

3) mast cells release histamine: histamine causes local blood vessels to dilate and capillary pores to widen

4) white blood cells are recruited: neutrophils and monocytes stick to blood vessel walls and move out of the bloodstream through a process called diapedesis

5) immune cells destroy bacteria: monocytes mature into macrophages in tissues. macrophages and neutrophils engulf and destroy the pathogens

what is the function of histamine

released by mast cells and is involved in inflammation

It:

• dilates local blood vessels, increasing blood flow

• increases capillary permeability by widening the spaces between capillary cells

• helps immune cells and fluid move from the body into the affected tissue

what causes redness during inflammation

local vasodilation increases blood flow to the affected area

what causes heat during inflammation

increased blood flow brings more warm blood to the area

what causes swelling during inflammation

increased capillary permeability and allows fluid to move into the tissues, producing edema

what causes pain during inflammation

inflammatory chemicals and swelling stimulate or sensitize sensory nerve endings

what are two classes of drugs that can suppress the inflammatory response

• nonsteroidal anti-inflammatory drugs

• glucocorticoids

what type of cells releases interferons

virus-infected cells

what are the steps that occur during an interferon response, from a virus entering a host cell to blocking viral multiplication

1) a virus enters a host cell and begins to replicate

2) the infected cell releases interferon

3) interferon binds to receptors on nearby, uninfected host cells

4) these cells produce inactive enzymes that can break down viral messenger RNA and inhibit protein synthesis

5) if a virus subsequently enters one of these prepared cells, the enzymes become activated

6) the activated enzymes interfere with viral replication, preventing the virus from multiplying effectively

why do natural killer cells destroy our own cells

when they become harmful, particularly:

• virus-infected cells

• cancer cells

What is the main function of complement proteins in our immune system

destroying foreign cells by punching holes in their membranes

How does the complement system destroy these cells

through the formation of membrane attack complex:

1) complement proteins are activated through a complement pathway

2) complement proteins 5-9 assemble

3) these proteins form a pore-like channel in the pathogens plasma membrane

4) substances leak through the opening, leading to the destruction of the cells

what are other things that complement proteins can do

• act as chemotaxins

• act as opsonins

• promote vasodilation and increased vascular permeability

• activate kinins

• amplify the inflammatory response

what are the two complement pathways

alternative and classical

alternative pathway

• how is it activated: complement proteins bind directly to a foreign invader and activate the complement cascade nonspecifically

• innate immunity

classical pathway

• how is it activated: complement proteins are activated through antibodies attached to a specific foreign invader

what is the main organ that provides a physical barrier that prevents pathogens from entering our body

the skin

what cells produce pigment that helps prevent tissue damage by UV rays

melanocytes

what kind of immune response is mediated by B cells

B cells mediate antibody-mediated immunity, also called humoral immunity

• when activated, B cells can differentiate into plasma cells that produce antibodies

• these antibodies recognize specific antigens and help the body eliminate pathogens

what are the two types of antigen recognition

• T-independent antigens: stimulate antibody production without assistance from T cells

• T-dependent antigens: typically protein antigens that require assistance from help T cells to stimulate antibody production

what is an antibody

a Y-shaped protein produced by plasma cells that binds to a specific antigen

how to antibodies help protect the body

• physically hindering antigens: binding to a pathogen or antigen and interfering with its ability to cause harm

• amplifying innate immune responses: helping other immune mechanisms recognize and destroy pathogens

• activating the classical complement pathway: promoting complement-mediated destruction of foreign cells

what is a plasma cells

an activated B cell that specializes in producing and secreting antibodies

where do plasma cells originate

when B cells encounter their matching antigen and become activated. T-dependent antigens also require help from helper T cells to stimulate the B cell response

Antigen-binding region

the variable regions at the tips of the Y-shaped antibody bind to a specific antigen

antibody class

determined by the antibody’s constant tail region, which is associated with its heavy chain

what are the 5 antibody classes and their characteristics

• IgM: early plasma cell response

• IgG: very specific response to bacteria and viruses

• IgE: involved in responses to parasitic worms and allergic reactions

• IgA: found in secretions

• IgD: found on the surface of B cells

when does clonal selection occur

when an antigen selects and activates a B cell with a receptor specific to that antigen

what happens during clonal selection once a B cell is activated

1) a specific antigen binds to its matching B cell receptor

2) for a T-dependent antigen, interaction with a helper T cell helps activate the B cell

3) the activated B cell divides repeatedly, producing a clone of identical cells

4) most of these cells differentiate into plasma cells, which secrete antibodies

5) some differentiate into memory B cells, which remain ready to respond to future encounters with the same anitgen

Active immunity

• the body produces its own antibodies after exposure to an antigen

• the immune system generates its own response

passive immunity

• the body receives preformed antibodies from another source

• the antibodies are borrowed rather than produced by the recipient

what are the 3 main types of T cells

• cytotoxic

• helper

• regulatory

Cytotoxic T cells

• destroy host cells containing foreign material

• frequently target cells infected with viruses

• secrete chemicals that destroy target cells

Helper T cells

• coordinate and amplify the activities of other immune cells

• secrete chemicals that promote the activity of other immune cells

• produce factors that support B and T cell growth and immune cell recruitment

regulatory T cells

• suppress immune responses

• help regulate immune activity

How do T cells recognize that a cell needs to be destroyed

T cells respond to antigens presented to them by antigen-presenting cells

How does a cytotoxic T cell destroy a target cell that has been infected with a virus

1) it recognizes its target through specific antigen recognition

2) it then releases chemicals that destroy the target cell

3) the infected host cell is eliminated, helping prevent it from continuing to produce viruses

what is immunodeficiency

it occurs when the immune system is unable to provide an adequate defense against infections or other threats

• can result in increases susceptibility to infections

What is SCID- severe combined immunodeficiency

a group of rare genetic disorders in which the immune system has severe defects affecting both T and B cell immunity

when does an autoimmune disease occur

when the immune system mistakenly attacks the body’s own cells, tissues, or organs instead of distinguishing them from foreign threats