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By the end of the lesson I will: Objectives By the end of the lesson I will: Know a PATHOGEN is a micro-organism that causes an infectious disease Know pathogens reproduce before they make enough toxins to make you feel ill Know that the best way to protect ourselves is through the first line of defence (the skin) and not let any pathogens into the body Identify the second and third line of defence Know what the white blood cells do to protect your body
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GCSE Core Science Human Biology
Key WordsKey WordsWHITE BLOOD CELL, WHITE BLOOD CELL, INGEST, ANTIBODY, ANTITOXININGEST, ANTIBODY, ANTITOXIN
GCSE Core Science Human BiologyObjectives
By the end of the lesson I will: •Know a PATHOGEN is a micro-organism that causes an infectious disease •Know pathogens reproduce before they make enough toxins to make you feel ill•Know that the best way to protect ourselves is through the first line of defence (the skin) and not let any pathogens into the body• Identify the second and third line of defence•Know what the white blood cells do to protect your body
GCSE Core Science Human Biology
There are four main ways in which you can get sick1. Droplet infection – When a sick person coughs,
sneezes or talks too close to you2. Direct contact – through skin, kissing or other
sexual contact3. Contaminated food and/or drink – ingestion4. Break in the skin – scratches or needle punctures
Starter
GCSE Core Science Human Biology
We are going to grow some yeast…..
AND THEN KILL IT!AND THEN KILL IT!1. Using ASEPTIC TECHNIQUE infect a petri dish with a
yeast solution.
2. Wait for the solution to slightly dry (perhaps 1hour)
3. Place a full drop of antiseptic onto the centre of the agar plate.
4. Incubate for 24-48hours.
WHAT ARE YOU TRYING TO FIND OUT? WHAT ARE YOU TRYING TO FIND OUT?
WHAT DO YOU EXPECT TO FIND OUT?WHAT DO YOU EXPECT TO FIND OUT?
How do we effect change?
I know HOW TO USE ASEPTIC TECHNIQUE
GCSE Core Science Human BiologyLines of defence How many
lines of defence do
you have in your body?
1) Skin: Provides both a physicalphysical (protective layer that completely wraps around the body, shielding blood vessels, nerves, muscles, organs, and bones) and a chemical barrierchemical barrier (When there is a cut or tear in the surface of the skin pathogens can breach the bodies defence and so glands beneath the skin produce an enzyme that helps kill bacteria)
GCSE Core Science Human Biology
2) Mucous membranes, stomach acid, cilia: • Mucous membranes, produce a sticky substance that traps
irritants that enter through the nose.
• Structures like tiny hairs, called cilia, line the body's airways and constantly wave foreign particles and mucus away from the lungs to where they can be swallowed safely.
• Most harmful microbes that make it to the stomach are destroyed by stomach acids.
• Tears and saliva both contain enzymes that destroy invaders.
• The brain-blood barrier, a specialized "filter" that surrounds the brain and spinal cord and acts as a physical barrier to keep out proteins, toxins, and most microbes, while letting in glucose, the source of the brain's nutrients.
Lines of defence
GCSE Core Science Human Biology
3) Lymphatic system (white blood cells): You have white blood cells in your body that defend it by•Ingesting pathogens and destroying them (Never EVER say Ingesting pathogens and destroying them (Never EVER say they eat the pathogen as this is WRONG. The only correct they eat the pathogen as this is WRONG. The only correct word is INGEST)word is INGEST)•Some white blood cells produce antibodies that recognise the antigens that are on the surface of the pathogen. The anitbodies of the white blood cell then bind with the antigens of the pathogen which destroys the pathogen or tags it for ingesting by another white blood cell. Each antigen is different and so your body needs to produce an antibody to match each antigen.•Some white blood cells produce antitoxins to counteract the toxins produced by some bacteria. The toxins are bound and destroyed.
Lines of defence
GCSE Core Science Human Biology
GCSE Core Science Human Biology
Lines of defence
GCSE Core Science Human Biology
physical and chemical barriers
most essential
mostcontrollable
non-specific defences
pathogen-specific defences
ingestion of bacteria by white cells
inflammationto attract white
cells into tissues
involves antibodies and T- and B-cells
GCSE Core Science Human BiologyDelayed response
The B-lymphocyte that produces the correct antibody for the antigen begins dividing to produce many more antibody-producing cells.
It takes a few days to produce enough antibodies to destroy the pathogen. This means there is delay between infection and the person beginning to feel better.
Once a pathogen has been destroyed, a few memory cells remain. These recognize the pathogen if it re-infects, and make the immune response much quicker and more effective. This is called active immunity.
GCSE Core Science Human BiologyResearch
Use pages 64-65 to complete theProvided worksheets on
‘White Blood Cells’ OR
‘Infection’Miss will pair you with someone who Miss will pair you with someone who
you will work with. You will you will work with. You will complete a different sheet each.complete a different sheet each.
You will then have toYou will then have toteach what you haveteach what you have
learnt to yourlearnt to yourpartner!partner!
GCSE Core Science Human BiologyObjectives
By the end of the lesson I will: •Know a PATHOGEN is a micro-organism that causes an infectious disease •Know pathogens reproduce before they make enough toxins to make you feel ill•Know that the best way to protect ourselves is through the first line of defence (the skin) and not let any pathogens into the body• Identify the second and third line of defence•Know what the white blood cells do to protect your body
