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CHAPTER 1 : TRANSPORT

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  1. CHAPTER 1 : TRANSPORT 1.5 - The Role of the Circulatory System in the Body's Defence Mechanism

  2. 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

  3. 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.

  4. MAIN LINES OF DEFENCE • Non-Specific Defence : First line defence & Second line defence • Specific Defence : Third line defence

  5. 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

  6. 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)

  7. 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

  8. 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.

  9. 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

  10. MECHANISM TO DESTROY ANTIGENS 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.

  11. IMMUNITY, IMMUNISATION & VACCINE • 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

  12. Defence system Divided into Non specific specific is Divided into 3rd line 1st line 2nd line through are produce eg lymphocyte antibody Phagocyte Carry out • Skin • mucous membrane gives immunity Phagocytosis Divided into active immunisation passive Divided into Divided into artificial natural natural artificial

  13. 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)

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

  15. 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

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

  17. 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!!!

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