Post on 11-May-2015
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CHAPTER 11 : IMMUNITY (5 hrs)
11.1 Immune Response (2½)
11.2 Development of Immunity (1½)
11.3 Immune Disorder ( 1 )
• Describe what is meant by immunity.• Describe the structure of antibody
and state the classes of antibodies.• Explain and compare humoral and cell
mediated immune response• Describe the roles of lymphoid organs
in immunity.• Describe various types of antigen and
antibody reactions.
11.1 : Immune Response (Objectives)
What is: Immunity ? Antigen ? Antibody ?
Structure of antibody
Classes of antibody
Immune response
Antigen & antibody reactions
11.1 : Immune Response
IMMUNITY
• Immunity = is a body defense against the many potentially dangerous viruses, bacteria and other pathogens.
• Involves the immune system.• Immune system = the body system
responsible for resisting disease.
Body Defense System
1st line of defense
2nd line of defense
3rd line of defense
Disease
Physical barrier that block the entry of antigen
Block the spread of antigen into the body
Specific defense system (immune system)
1st line of defense
Sweat, mucus, saliva, gastric acid, tears
Skin mucous membrane
2nd line of defense
Cut of the skin causes:- Damaged cells release chemical signal
Attract phagocytic WBC to the infected tissue
Stimulates blood clotting Ingest antigen by phagocytosis
Inflammatory response
Heat
Swelling
Pain
Redness
Defense System
Non-specific defense mechanismsSpecific defense
mechanisms (immune system)
1st line of defense 2nd line of defense
3rd line of defense
skin mucous membrane secretions of skin & mucous membrane
phagocytic leukocyte antimicrobial protein inflammatory response natural killer cell
Lymphocyte Antibodies
Ability of the body to recognize & protect itself against foreign substance that can cause disease
3rd line of defense (Immune System)
Immunity
Cell (eg: virus, bacteria) pathogen Soluble toxin, protein (eg: venom)
Foreign substance ?
CELL-MEDIATED CELL-MEDIATED IMMUNITYIMMUNITY
HUMORAL HUMORAL IMMUNITYIMMUNITY
SPECIFICSPECIFICIMMUNEIMMUNE
RESPONSERESPONSE
PHAGOCYTOSISPHAGOCYTOSIS
INFLAMMATIONINFLAMMATION FEVERFEVER
LEVELS OF DEFENSE AGAINST INFECTION
NONSPECIFICNONSPECIFICINTERNALINTERNALDEFENSESDEFENSES
If barriersIf barrierspenetrated:penetrated:
MUCOUS MUCOUS MEMBRANESMEMBRANES
(respiratory & digestive(respiratory & digestivetract) tract)
If nonspecificIf nonspecificinsufficient:insufficient:
NATURAL KILLER CELLSNATURAL KILLER CELLS
SKINSKIN(physical)(physical)
BARRIERSBARRIERS
Foreign substance that can provoke an immune response
Due to the presence of foreign molecules (usually protein on the membrane surface)
Intruder non-self
Antigen (Antibody generators)
Definition
Only a certain parts of antigen can provoke immune response
These parts ~ antigenic determinants (epitope)
Usually 1 antigen has many epitopes
Different epitope binds with different antibody
Antigenic determinants / Epitope
Blood Cell
Leukocyte Platelet
Granulocyte Agranulocyte
Neutrophil Eosinophil Basophil
Erythrocyte
LymphocyteMonocyte
Types of Blood Cells
Macrophage
Phagocytic
Phagocytic
differentiate
Produced in bone marrow
Lymphocytes
Remain & mature in Bone
Migrate & mature in Thymus
Lymphocyte
T cellB cell
Mature B & T cells migrate to lymphoid organ
Lymphoid Organ
Thymus
Spleen
Tonsil
Lymph Node
Bone Marrow
Lymphoid Organs
1
2
3
4
5
Small, round organ Found at intervals along lymphatic
capillaries Embedded in connective tissue
1. Lymph Nodes
Filter lymph Macrophage remove & destroy antigen Lymphocyte monitor presence of antigen &
activate immune system
Function
Bi-lobed structure (lower neck region) Size varies with age Childhood ~ larger, adolescent ~ stop
growing & reduce in size
2. Thymus
Secrete thymosin for T cell maturation
Function
In adult, red bone marrow ~ skull, spinal column, femur
Produce stem cells ~ differentiates into different types of blood cells
3. Bone Marrow
Site of blood cells synthesis Site of B cell maturation
Function
Largest lymphoid organ Curved-shaped (left side of stomach beneath
diaphragm) Consist of :-
White pulp - macrophage & lymphocyte Red pulp - RBC & macrophage
4. Spleen
Blood reservoir Remove & destroy antigen & worn-out blood
cells
Function
Simplest lymphoid organ Ring-like structure (around pharynx) Epithelium surfaces invaginate form crypts
5. Tonsils
Trap & remove pathogens that enter via nose & mouth
Protect respiratory system
Function
When activated, B cell differentiate to form plasma cell
That secrete antibody
B cell
A specific protein, immunoglobulin (Ig) that can bind to specific antigen
Produced by plasma cells Due to the presence of antigen
Found in plasma
Definition of antibody
Y-shaped
Has 4 polypeptide chains 2 heavy (H) chains 2 light (L) chains
Polypeptide chains are held together by disulfide bonds
Form antibody monomer
Antibody ~ Structure
Each chain has 2 regions Constant (C) region Variable (V) region – which binds to
antigen
Antibody ~ Structure
5 classes ~ based on the differences of C region
Classes of Antibody
Ig M1
2 Ig A
Ig D3
4 Ig G
5 Ig E
5-10% Largest, 5 monomer
(pentamer) Held together by a joining, J-
chain Most reactive 1st antibody produced during
first exposure to antigen
1. Ig M
Agglutinating antigen Complement fixation
Function
10-15% 2 monomers (dimer) Produced mainly by mucous membrane (secretory cells) Found in saliva, mucus, sweat, GI tract, tears, milk
(colostrum)
2. Ig A
Prevent attachment & entry of antigen to epithelial surfaces
Protect mucosal surface
Function
Less than 1% Monomer Mainly found on the surface of B-cells (antigen receptor)
3. Ig D
Function Act as antigen receptor on B cell
Help to stimulate B cell to differentiate to plasma cell & memory B cell
Help to initiate development of humoral immunity
Most abundant (75 - 85%) 1 monomer, smallest Can cross placenta Long lasting (mostly memory cells)
4. Ig G
Provide passive immunity (temporary protection) to fetus
Complement fixation
Function
0.002% (least produced) Monomer (slightly larger than IgG) Found on the surface of basophils & mast cell Release histamine when triggered by antigen
Promotes inflammation Responsible for allergic reaction
5. Ig E