Biology- Disease and Immunity
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- Created by: Kitsune
- Created on: 11-02-17 15:37
What is a disease?
A state of the body when it can't cope with changes by normal homeostatic methods
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What are pathogens?
Disease causing organisms
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What is a transmissible disease?
A disease in which the pathogen can travel from one host to another
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How can transmissible diseases be passed?
By direct contact (blood & other body fluids) and by indirect contact (food, animals & air)
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Why does human food have to be protected?
Otherwise it may contain organisms which are decomposers or pathogenic
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Eating contaminated food can lead to...
food poisoning
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How does food poisoning work?
Microbes start reproducing. They release toxins and feed on host tissue
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How to keep food hygienic?
Don't contaminate it, don't allow the microbes to reproduce, destroy remaining bacteria by cooking thoroughly
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How do pathogens cause harm?
By secreting poisons, they can reproduce so much they will cause direct damage, they can trigger the immune response and cause swelling or an increase in temperature
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What are bacterial diseases treated with?
Antibiotics
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What are the 4 ways of controlling the spread of disease?
Hygienic food preparation, good personal hygiene, waste disposal, sewage treatment
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What defenses does the body have against disease?
Chemical, mechanical and physical
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What are the body's mechanical defenses against pathogens?
Skin and hairs in the nose
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What are the body's chemical defenses against pathogens?
Bacterial wax in years, stomach acids, enzymes in tears
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What are the body's physical defenses against pathogens?
Cilia and mucus secreting cells, white blood cells
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What does blood clotting do?
It reduces loss of blood and seals the wound against pathogens
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Describe how a scab is formed.
When the skin is wounded platelets release chemicals. Soluble fibrinogen proteins form a mesh of insoluble fibrin fibre across the wound. Platelets stick together to form clumps that stick in the mesh. RBC get stick forming a clot=> scab
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What do WBC do?
They recognize antigens on the surfaces of antigens and destroy the pathogens
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How are phagocytes attracted to a wound?
By chemical messages
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Describe phagocytes
They have a long lobbed nucleus which allows them to squeeze between the cells and they have sacks with powerful digestive enzymes
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How do phagocytes destroy pathogens?
They flow around them, enclosing them in a sac. The digestive enzymes are poured into the sac. The pathogen is destroyed and the phagocyte absorbs the products for digestion
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What is an antibody?
A protein produced by an antibody in response to an antigen. They help to destroy the pathogen.
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How do lymphocytes work?
They are stimulated when they come in direct contact with the pathogen and produce antibodies
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What is an antigen?
A protein/carb on the surface of the pathogen which can provoke the host's immune system
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Why are specific antibodies needed for different antigens?
Each antigen has a specific shape
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What types of immunity are there?
Active and passive
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What is active immunity?
A defense against a pathogen by antibody production in the body
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Why is active immunity long term?
Because memory cells formed in lymphocytes retain the ability to produce antibodies
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What is natural active immunity?
When the individual produces antibodies
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What is artificial active immunity?
When a weakened pathogen is injected by vaccination
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What is passive immunity?
Short-term defense against a pathogen by antibodies acquired from another individual
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Why is passive immunity short term?
No memory cells are produced
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What is natural passive immunity?
When the mother's antibodies are passed to the infant through breast milk
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What is artificial passive immunity?
When the person is injected with a serum (animal antibodies)
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Describe vaccination
Harmless pathogens which have the antigens are injected. Antigens trigger an immune response. Lymphocytes produce antibodies. Memory cells are made, giving long-term immunity
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How can an immune response cause an autoimmune disease?
The body's antibodies start attacking own cells.
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What happens in type 1 diabetes?
Insulin producing cells are destroyed
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How does allergy work?
The body becomes sensitive and overreacts to substances, causing swelling and tissue damage
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How does transplant rejection work?
Lymphocytes recognize foreign antigens and destroy them
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Other cards in this set
Card 2
Front
What are pathogens?
Back
Disease causing organisms
Card 3
Front
What is a transmissible disease?
Back
Card 4
Front
How can transmissible diseases be passed?
Back
Card 5
Front
Why does human food have to be protected?
Back
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