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CHAPTER 1 : TRANSPORT

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

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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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