human body defenses Flashcards
fever
elevation of body temp above 38C
other causes-
ovulation, increase secretion of thyroid hormone, tumors, reaction to vaccines, and drugs
benefits of fever
- ) decreases viral reproduction
- ) inhibits bacterial growth and reproduction
- ) speeds repair
Adaptive immunity
It is the ability of the human body to defend itself against specific invading agents, such as bacteria, toxins, virus and foreign tissue
characteristic of adaptive immunity
Specificity:
recognizes specific foreign antigen and reacts to it
adaptivity memory
second response to antigen stronger and faster
what is an antigen
: any substance that causes your body to produce antibodies against it
reacts with antibody
what is an antibody
protein (immunoglobulin) produced in response to an antigen
Large Y-shaped protein that identify and help remove antigens or targets like bacteria or viruses
epitopes (antigenic determinant)
actual region of the antigen that reacts with the antibody (5-7 a.a)
exogenous antigen
those outside cell body (bacteria, bacterial toxins, parasitic worms, inhaled pollen and dust, and viruses that have not infected cells yet.
endogenous antigen
Those inside the cell body viral proteins produced after virus infects the cell, toxins produced by intracellular bacteria, or abnormal proteins synthesized by a cancerous cell.
what is MHC ?
MHC encodes antigens on the surface of the cell.
MHC can display both “self” peptides and foreign peptides from broken down intracellular proteins
MHC I
Type 1
Present on every nucleated cell in the body
They present antigens that arise from cytoplasm. The present self Pr-, as well as viral Pr- that take over the cell in order to replicate the virus
Present to cytotoxic T-cells
Bhind CD8 adhesion molecules on cytotoxic Tcells
MCH II
Type 2
Only occur on specialized antigen-presenting immune cells like macrophages or dendritic cells that engulf bacteria
They present antigen to T-cells or B-cells that produce antibodies.
Type 2’s present exogenous antigens that originate extracellularly from foreign bodies such as bacteria
Bind CD4 adhesion molecules on helper Tcells
antigen presenting cell (APC)
a macrophage or dendritic cell digests an intracellular pathogen then presents the remains (small peptides or antigens) on the surface
helper T cell
recognizes the presentation and helps stimulate other killing cells
cytotoxic t cell
primed for killing after stimulation by message from Helper T cells
cell mediated response
helper T cells and cytotoxic T cells
triggered by cytotoxic T cells recognizing antigens
effective mostly against viral-infected cells, cancer cells, fungal and protozoan infections & foreign tissue (transplants)
Inside the cell
humoral response
production of antibodies
Which act against bacteria, bacteria toxins and viruses outside body cells
characteristics of antibodies
ability to react with a specific antigenic determinant which stimulated its production chemical composition: immunoglobulin protein two heavy chains and two light chains
when antigen and antibody bind
Neutralizes antigens Immobilizing bacteria Agglutinating (clumping together) and precipitating antigens activates complement cell lysis facilitates phagocytosis
gmade
IgG, IgM, IgA, IgD, IgE
IgG
80 – 85 % of circulating antibodies
Long lasting
Found in blood, lymph and intestine
Protects against bacteria and viruses by:
Enhancing phagocytosis, neutralizing toxins, and triggering the complement system
Can crosses placenta
IgM
5 to 10% of all antibodies in blood, also found in saliva
largest in physical size
first antibody produced in initial exposure to an antigen
activates complement, causes Agglutination and lysis of microbes
responsible for RBC ABO incompatibility reaction
IgA
predominant in normal body secretions
sweat, tears, salvia, mucus, breast milk and gastrointestinal secretions
prevents bacteria and viral attachment and invasion via mucous membranes
levels decrease during stress
IgD
about 0.2 % of antibodies in blood
found on the surfaces of B cells as antigen receptor
activates B cells
IgE
*principle antibody in allergic response
attached to mast cells and causes histamine release resulting in inflammation
systemic release may lead to anaphylactic shock
provides protection against parasitic worms
autoimmunity
Pathological response
immune system attacks its own body cells (loss of immune tolerance, or recognition of self!)
haptens
is a small molecule which can elicit an immune response only when attached to a large carrier such as a protein forms a hapten carrier adduct
The hapten and the carrier alone do not elicit an immune response by itself
E.g. urushiol - the txin found in poison ivy.
absorbed through the skin - oxidation in the skin cells -quinone (hapten) - reacts with skin proteins - hapten adducts.
Some haptens can induce autoimmune diseases
Hydralazine (antihypertensive) drug-induced lupus erythematosus in certain individuals
Halothane (anaesthetic gas) life-threatening hepatitis
