To state another function of the circulatory system

To identify the three lines of defence mechanism

To describe phagocytosisTo state the meaning of antigen & antibody

WHY DO WE NEED THE BODY’S DEFENCE MECHANISM?

To defend the body against disease-causing microorganism (pathogens)

Pathogens are bacteria, viruses & parasites

Transmitted by air, contaminated food & water, animal (vector) & contaminated needles. Also by contact.

Non-Specific Defence : First line defence & Second line defence

Specific Defence : Third line defence

BODY’S DEFENCE MECHANISM

NON-SPECIFIC SPECIFIC

1ST LINE 2ND LINE 3RD LINE

SKIN : sweat, sebum

MUCOUS MEMBRANES : secretion of mucus

Phagocytosis by phagocytes

Antibodies produced by lymphocytes

Skin – physical barrier (dead keratinised layer difficult to penetrate

If there is a cut, the blood clots quickly to prevent blood loss & entry of m/organisms

Tears secreted by tear gland & acidic sebum (sebaceous gland) – contain lysozymes which destroy some bacteria

Mucus (mucous membrane) in nasal cavity & trachea traps dust particles & microbial spores

The cilia (respiratory tract) sweep the trapped particles to the pharynx swallow into stomach (secretes HCl)

The phagocytic white blood cell are attracted by chemicals produced at the sites of infection and move to these sites.

Engulf & digest the pathogensThe soluble products are absorbed &

assimilated by the phagocytesMay also be destroyed by toxins produced

by the pathogensNumber of leucocytes increases to try to

destroy the pathogen & neutralise the toxin

In higher group of animals have a more specific immune defence mechanism against pathogen IMMUNE SYSTEM

Two main types of lymphocytes :B-lymphocytes produce antibodiesT-lymphocytes attack cells infected by

pathogen or which produce certain chemicals to coordinate the immunes response.

ANTIGENS – large complex molecules (proteins/polysaccharides) that the immune system recognises as foreign found on the cell membrane of m/organisms/dissolved in the blood plasma/interstitial fluid.

ANTIBODIES – A protein produced by lymphocytes in response to the entry of an antigen into the body.

IMMUNE RESPONSE – interaction between antibody & antigen which result in the antigen being eliminated from the body

AGGLUTINATION : the clumping of antigens easy targets for phagocytes to destroy

NEUTRALISATION : toxin are made non-toxic by reaction with the antibodies

LYSIS : lysin (antibodies) bind to antigens cause antigens/pathogens to rupture

OPSONISATION : The binding of antibodies to antigens stimulate phagocytes (macrophage) to destroy the antigens.

IMMUNITY : The state in which the body is resistant to infection by a disease-causing pathogens @ the ability of an animal or plant to resist infection by pathogens

IMMUNISATION : The process of inducing immunity by administering a vaccine

VACCINE : A preparation of weakened, dead or non-virulent forms of a pathogen

Defence system

specificNon specific

1st line 2nd line3rd line

•Skin

•mucous membrane

Phagocyte

Phagocytosis

lymphocyte antibody

passive active

naturalartificial natural artificial

immunisation

immunity

Divided into

Divided into is

throughproduce

gives

Divided into

Divided into Divided into

are

Carry out

eg

ACTIVE IMMUNITY : when an individual’s own immune system produces its own antibodies to defend against specific antigens

Natural Active Immunity : after recovered from certain disease (examples : mumps, measles & chicken pox)

Artificial Active Immunity : can be established upon immunisation or vaccination. (mumps, rubella, measles & poliomyelitis)

PASSIVE IMMUNITY : when an individual is given the antibodies required to defend against the pathogen

Natural Passive Immunity : when antibodies produced by the mother are passed across the placenta to the foetus during development or in early infancy through breast milk (breast feeding). Colostrum (1st formed milk) – rich in antibodies

Artificial Passive Immunity : ready-made antibody or serum is injected into the individual. Prepared from cows or horses. (rabies, hepatitis, tetanus & snakebites)

Ooo…sleeping in Biology class ek?

So stubborn la.Let me ‘teach’ U first before Mr. FAZLI become angry!!!

Waa….mama! Help me…. I don’t want to fall asleep

in the class anymore!!!I SWEAR!!!