Sub 1.5 Body Defence Mechanism
Transcript of Sub 1.5 Body Defence Mechanism
![Page 1: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/1.jpg)
![Page 2: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/2.jpg)
LEARNING OUTCOMES
• To state another function of the circulatory system
• To identify the three lines of defence mechanism
• To describe phagocytosis• To state the meaning of antigen
& antibody
![Page 3: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/3.jpg)
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.
![Page 4: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/4.jpg)
MAIN LINES OF DEFENCE
• Non-Specific Defence : First line defence & Second line defence
• Specific Defence : Third line defence
![Page 5: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/5.jpg)
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
![Page 6: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/6.jpg)
FIRST LINE of DEFENCE
• 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)
![Page 7: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/7.jpg)
SECOND LINE of DEFENCE
• The phagocytic white blood cell are attracted by chemicals produced at the sites of infection and move to these sites.
• Engulf & digest the pathogens• The soluble products are absorbed &
assimilated by the phagocytes• May also be destroyed by toxins produced
by the pathogens• Number of leucocytes increases to try to
destroy the pathogen & neutralise the toxin
![Page 8: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/8.jpg)
THIRD LINE of MECHANISM
• In higher group of animals have a more specific immune defence mechanism against pathogen IMMUNE SYSTEM
• Two main types of lymphocytes :– B-lymphocytes produce antibodies– T-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.
![Page 9: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/9.jpg)
THIRD LINE of MECHANISM (cont…)
• 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
![Page 10: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/10.jpg)
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.
MECHANISM TO DESTROY ANTIGENS
![Page 11: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/11.jpg)
• 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
![Page 12: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/12.jpg)
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
![Page 13: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/13.jpg)
VARIOUS TYPES OF IMMUNITY
• 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)
![Page 14: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/14.jpg)
•Artificial Active Immunity : can be established upon immunisation or vaccination. (mumps, rubella, measles & poliomyelitis)
![Page 15: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/15.jpg)
VARIOUS TYPES of IMMUNITY
• 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
![Page 16: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/16.jpg)
• Artificial Passive Immunity : ready-made antibody or serum is injected into the individual. Prepared from cows or horses. (rabies, hepatitis, tetanus & snakebites)
![Page 17: Sub 1.5 Body Defence Mechanism](https://reader034.fdocuments.us/reader034/viewer/2022051323/54679ff0b4af9fda3f8b5538/html5/thumbnails/17.jpg)
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!!!