Immunity anat 2

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Immune system

A complex collection of cells and organs that destroys or neutralizes pathogens that would otherwise cause disease or death.

Innate Immunity (Nonspecific)

Protection present at birth against a wide variety of invaders, lacking memory and specific pathogen recognition (first and second lines of defense).

Adaptive Immunity (Specific/Acquired)

Immune response that targets specific foreign substances, retains memory of invaders, and functions as the third line of defense.

First Line of Defense

Surface barriers including skin, hair, and mucous membranes.

Second Line of Defense

Cellular and chemical mechanisms including mast cells, basophils, and phagocytes (monocytes, neutrophils, macrophages).

Phagocyte

A cell capable of surrounding and engulfing foreign particles or cells.

Neutrophils

First-responder phagocytes that specifically target bacteria.

Macrophages

Phagocytic cells located in tissues that constantly patrol for pathogens.

Dendritic cells

A specialized type of macrophage in the skin that functions as an antigen presenter.

Eosinophils

Leukocytes that specifically target parasitic infections.

Phagocytosis steps

1. Chemotaxis 2. Adherence 3. Ingestion 4. Digestion

Natural Killer (NK) cells

Non-specific lymphocytes that destroy abnormal host cells by secreting perforin and granzymes to induce apoptosis.

Interferons

Proteins secreted by virus-infected cells that signal adjacent uninfected cells to produce antiviral proteins.

Opsonization

The process of tagging a pathogen for phagocytosis by binding antibodies or antimicrobial proteins.

Complement proteins

A group of over 20 plasma proteins produced by the liver that circulate in blood in an inactive state.

Inflammation

A protective immunovascular response designed to isolate and eliminate injury causes, clear necrotic tissue, and initiate repair.

Hallmarks of Inflammation

Redness (rubor), heat (calor), swelling (tumor/edema), and pain (dolor).

Pyrogens

Chemicals that act on the hypothalamus to elevate body temperature, resulting in fever.

Fever

An elevated body temperature response that inhibits the growth of pathogens.

Line of defense with immunological memory

Third line of defense.

Antigen

An antibody generator; any substance recognized as foreign by the body that triggers an immune response.

Epitope (Antigenic determinant)

The specific region on a foreign molecule that stimulates an immune response.

Antibody

Specialized proteins produced by B cells that recognize foreign invaders and typically act as tags for destruction.

Antigen receptors

Cellular structures capable of recognizing specific foreign targets presented to them.

Antigen-presenting cells (APCs)

Specialized cells (such as macrophages, dendritic cells, and B cells) that display phagocytosed fragments to lymphocytes to initiate adaptive immunity.

T cells

made in the bone marrow and mature or receive

immunocompetence in the thymus.

Cytotoxic T cells

ka Killer T cells; effectors; directly kill infected cells

Helper T cells

antigen presenters, promote the action of cytotoxic T

cells

Memory T cells

remember and activate acquired immunity

pathogens

Antigens are extracted

from

MHC proteins

Antigens bind to

cell membrane

MHC proteins are

embedded in

T cells

Presented antigen will

activate

Antigen on MHC-1 proteins activate

cytotoxic T cells, which induce apoptosis

in specific infected cells through release of perforin and granzymes.

Antigen on MHC-2 proteins activate

helper T cells and memory T cells, which

activate B cells and stimulate macrophages, neutrophils, and natural killer cells

Immunocompetence

The ability of the body to produce a normal immune response following exposure to an antigen.

Major Histocompatibility Complex (MHC)

Surface proteins on cells that present antigens and identify cells as self.

MHC Class I (MHC 1)

MHC proteins found on all nucleated cells that present self and non-self antigens to T cells.

MHC Class II (MHC 2)

MHC proteins found only on macrophages, dendritic cells, and B cells that present non-self antigens for the initial activation of T cells.

B – Cells

made in bone marrow and mature in bone

marrow

Antibodies (secreted) and B cell receptors (membrane bound)

B cells make:

Plasma Cells

– produce antibody

Memory B cells

remember antigen and differentiate at future

exposure

Agglutination

Antibodies can bind to several antigens at the same time

causing “clumping”. These clumps are ingested by phagocytes. IgM being a

pentamer has a major role (it can bind 10 antigens at once).

Neutralization

Antibodies can occupy the active site of a virus thus

preventing its attachment, or the active site of a toxin and prevent it from

performing its action. This is the idea behind immunization against tetanus

or diphtheria to counteract their toxin.

Opsonization

antibodies (or complement) coat antigens and facilitate their

phagocytosis.

Complement fixation

he antibody changes shape when it binds to a cell

and exposes the complement-binding site. Complement will fix in that site

and is able to cause cell lysis.

The gastricjuices

Which of the following does(do) notbelong to the second line of defense?

Nonspecificresistance; adaptive immunity

__________ lacks the capacity to remember a pathogen or react differently to it in the future, whereas __________ utilizes memory cells to adapt to a given pathogen and ward it off more easily in the future.

Eosinophils

__________ are found especially in the mucous membrane, standing guard against parasites and allergens.

endogenouspyrexia

Complement fixation cannotlead to __________.

Interferons

__________ are secreted by cells infected with viruses, alerting neighboring cells and protecting them from becoming infected.

natural killercell

When an enemy cell is present, a(n)__________ secrete perforins, which bore a hole in the enemy cell membrane.

fever

A pyrogen is a substance that causes __________.

fever

__________ is not a cardinal sign characteristic of inflammation.

Redness

One group of proteolytic enzymes secreted by natural killer (NK) cells is __________.

granzymes

One group of proteolytic enzymes secreted by natural killer (NK) cells is __________.

immunity isdirected against a particular pathogen

One characteristic of the immune response is specificity. This means that __________.

artificialactive

Vaccination stimulates __________ immunity.

epitope

A(n) __________ is the region of the molecule that is recognized by antibodies.

thymus

T cells achieve immunocompetence in the __________.

majorhistocompatibility complex (MHC) protein

Helper T (T _H) cells recognize antigens when they are bound to a(n) __________.

Helper T (T _H) cells

__________ participate in both nonspecific resistance and immune response.

secrete granzymesand perforin

Cytotoxic T (T _C) cells are like natural killer (NK) cells because they both __________.

Differentiate intomemory antibodies, which upon reexposure to the same pathogen would mount aquicker attack

Which of the following is something antibodies do not do?

Which is the correct sequence of events in the humoral immune response?

Antigenrecognition → antigen presentation → clonal selection → differentiation →attack

IgG

__________ constitutes about 80% of circulating antibodies in plasma.

IgA

Which class of immunoglobulin provides passive immunity to the newborn during breastfeeding?

plasma cells

Before B cells secrete antibodies, they differentiate into _________.