Physiology Ahangari Final

what are two defense mechanisms

1. innate community (nonspecific)

2. Adaptive immunity (specific)

Innate immunity includes what kind of defenses, and what to these defenses represent?

- includes both external and internal defenses

these defenses are always present in the body and represent the first line of defense against invasion by potential pathogens.

what are three major groups of phagocytic cells?

1. neutrophils

2. the cells of the mononuclear phagocyte system, includes monocyte and macrophages.

3. organ-specific phagocytes in the liver, spleen, lymph nodes, lungs, bran (microglia)

Macrophages derived from ____ in the connective tissues. *Monocytes in the blood

monocytes

Why phagocytes remove foreign particles form the blood?

So that blood is usually sterile after a few passes through the liver and spleen.

The spleen contains what kind of cells?

Kupffer cells

_______ have a resident population of all leukocyte type.

Connective tissues

Link between chemotaxis and Leukocytes

Leukocytes act on the site of an infection by chemotaxis.

What is chemotaxis?

movement toward chemical attractants which are a subclass of cytokines known as chemokines.

During chemotaxis what kind of cells are the fist to arrive at the site of infection?

Neutrophils

What kind of cells arrive later?

Monocytes which can be transformed into macrophages.

What area of the brain regulated temperature?

hypothalamus in response to PGE2

Temperature mechanism

the release of PGE2 occurs from a pyrogen which acts as a trigger.

The _____ generates a response a response back to the rest of the body, making it _______ the ____.

hypothalamus

increase

temperature set-point

Substance that induces fever?

Pyrogen

Pyrogens can be either?

internal

or external

internal pyrogens are called?

external pyrogens are called?

endogenous

exogenous

Cytokines such as (interleukin 1) are a part of the innate immune system, produced by phagocytic cells, and can cause? _____

increase in the thermoregulatory set-point in the hypothalamus.

examples of endogenous pyrogens

interleukin 6 (IL-6) and the the tumor necrosis factor-alpha

Cytokine factors are released into general circulation, and they migrate to and produce what effect in the brain?

migrate to the circumventricular organs of the brain, where the blood-brain barrier is reduced.

cytokine factors bind with _____ on vessel walls

or

interact with local ___ cells

endothelial receptors

microglial

What happens when cytokine factors bind?

they activate the arachidonic acid pathway

PGE2 release comes from what kind of pathway?

arachidonic acid pathway

arachidonic acid pathway as it relates to fever is mediates by ?

enzymes phospolipase A2 (PLA2), cyclooxygenase-2 (COX-2), and prostaglandin E2 synthase

What do the previous enzymes to?

mediate the synthesis and release of PGE2.

What is the ultimate mediator of the febrile response?

PGE2

What is an antigen or immunogen

a molecule that stimulates an immune response

Antigens are usually?

protein or polysaccharides

(includes parts such as coats, capsules, cell walls, flagella, fimbrae, and toxins of bacteria, viruses, and other microorganisms

when combined with proteins and polysaccharides, lipids and nucleic acids are?

antigenic

what stimulates the production of specific antibodies?

antigen

What are haptens?

low molecular weight molecules

hapten contain?

an antigenic determinant but which are not itself antigenic unless complexes with an immunogenic carrier

if hapten binds to protein it thus becomes?

an antigenic determinant on the proteins

what are the 3 major types of lymphocytes?

T cells,

B cells,

and natural killer (Nk cells)

Nk cells are part of an innate immune system and ______?

play a major role in defending the hosts from tumors and virally infected cells

how are NK cells activated?

in response to a family of cytokines called interferons

What do activated NK cells release?

cytotoxis (Cell-killing) granules which then destroy the altered cells

the response of the organism to the pathogen?

inflammation

______ secrete antobodies that can bind to antigens in a specific fashion?

B lymphocytes

Also known as immunoglobulins?

antibody proteins

where are antibody proteins found?

gamma globulin class of plasma proteins

what are the 5 distinct bands of protein that apear?

albumin

alpha-1 globulin

alpha-2 globulin

beta globulin

gamma globulin

how were the 5 distinct bands of protein that are identified by what technique?

electrophoresis

what are the five immunoglobulin subclasses

IgG

IgA

IgM

IdD

IgE

Most antibodies in serum are in which subclass?

IgG

Antibodies in external secretion (saliva and milk)

IgA

Antibodies in the ______ are involved in _______?

IgE

Allergic reaction

how many polypeptide chains are antibodies composed of?

four polypeptide chains

describe the four polypeptide chains of antibodies?

two are heavy (H) and two are light (L)

T/F the combination of antibodies with antigens does not itself cause destruction of the antigens or the pathogenic organisms that contain these antigens

TRUEEEE

what do antibodies do?

serve to identify the targets for immunological attack and to activate nonspecific immune processes that destroy the invader

Example of bacteria thats buttered with antibodies

better targets for phagocytosis by neutrophils and macrophages

What is the ability of antibodies to stimulate phagocytsis?

opnosizantion

immune destruction of bacteria is also promoted by?

antibody-induced activation of a system of serum proteins known as a complement

Complement protein

C1 - C9

Where are C1-C9 proteins present and in what state?

present in an inactive state within plasma and other body fluids and become activated by the attachment of antibodies to antigens

Complement proteins can be subdivided into three components?

1. recognition - C1

2. Activation - C4, C2, and C3. in that order

3. Attack - C5 through C9

Recognition

C1

Activation

C4, C2, and C3

Attack

C5 through C9

Attack phase consists of complement fixation which is ?

when complement proteins attach to the cell membrane and destroy the victim cell

IgG and IgM antibodies activate?

C1

what does C1 catalyle?

the hydrolysis of C4 into two fragments = C4a and C4b

T/F The C4b fragment binds to the cell membrane and become an active enzyme?

TRU

How is C3 cleaved into C3a and C3b ?

the splitting of C2

C3b converts C5 into C5a and C5B

TRUE

what do C3a and C5a stimulate?

mast cells to release histamine;

What else does C5a do?

serves as a chemokine to attract neutrophils and monocytes to the site of infection

What do C5 and C9 do?

they are inserted into the bacterial cell membrane to form a membrane attack complex

Describe an attack complex

a large pore that can kill the bacterial cell through the osmotic influx of water

T/F antibodies directly kill the cell?

F completement proteins do

What do antibodies do then?

serve only as activators of this process in the classic pathway

CD8+T (a T Cell subset) associates with ?

MHC class 1

CD4+T (a T cell subset) associates with?

MHC class 2

The middlemen of the adaptive immune system

Helper T Cells

Once activated ______ divide rapidly and secrete small proteins called ______?

Helper T cells

cytokines

What do cytokines do?

regulate or "help" the immune response

What do helper Tcells differentiate into from the cytokine signals recieved?

Th1, Th2, Th17 or other subsets

*** secret different cytokines

Cytotoxic T cells destroy?

virally infected cells and tumor cells, and are also implicated in transplant rejection

Cytotoxic cells are also known as ?

CD8+ T cells because they express the CD8 glycoprotein at their surface

How can cells be transformed into suppressor T cells?

CD8+T cells interacting with helper T cells

Suprressor T cells prevent?

autoimmune diseases such as experimental autoimmune encephalomyelitis (MHC 1)

Subset of antigen-specific T cells

memory T cells

What do memory T cells do?

Persist long-term after an infection has resolved

How do Memory T cells provide the immune system with "memory" against past infection.

they quickly expand to large numbers of effector T cells upon re-exposure to thier cognate antigen

subtypes of Memory T cells?

-TCM cells (central memory T cells)

-TEM cells (effector memory T cells)

Memory cells may be either?

CD4+ and CD8+

Regulatory T cells (Treg cells) are formerly known as ?

suppressor T cells

What are regulatory T cells crucial for?

the maintenance of immunological tolerance

What are regulatory T cells major role?

Shur down T cell mediated immunity towards the end of an immune reaction and to suppress auto-reactive T cells that escaped the process of negative selection in the thymus

Two major classes of CD4+ regulatory T cells?

1. naturally occuring Tref cells ( also known as Cd4+cd25+foxp3+treg cells)

2. adaptive treg cells (Tr1 and Th3)

naturally occuring treg cells arise in the?

thymus

Adaptive treg cells may originate during?

a normal immune response

A special kind of lymphocyte that bridges the adaptive immune system with the innate immune system

Natural Killer T cells

conventional T cells recognize peptide antigen presented by major histocompatability complex (MHC) molecules

vs. NKT cells which recognize?

glycolipid antigen presented by a molecule called CD1d

Autoimmunity disease

Diabetes type I

failure of an organism to recognize its own constituent parts (down to the submolecular levels) as "self"

autoimmunity

results in an immune response agaisnt its own cells and tissues?

autoimmunity

immune disease include?

autoimmune diseases

complex diseases

allergies

Allergies can be broken down due to their sensitivity can be?

immediate hypersensitivity

delayed hypersensitivity