Human Defence Systems Flashcards
Name 3 non specific human defences
Skin, nose, stomach, trachea and bronchi
How does the skin defend against disease
If it is cut or grazed it immediately begins to heal itself, often by forming a scab, which prevents infection as the skin acts as a physical barrier.
How does the nose defend against disease.
Give 2 reasons
Cells in the nose produce mucus. This traps pathogens before they can enter the lungs.
The nose has internal hairs, which act as a physical barrier to infection.
How does the stomach defend against disease
Stomach acid- hydrochloric acid- is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water. Stomach acid is a chemical barrier against infection.
How does the trachea and bronchi defend against disease
The ciliated cells waft their hairs and move mucus and pathogens upwards towards the throat where it is swallowed into your stomach.
Explain how white blood cells help to defend
against pathogens by phagocytosis.
Phagocytes surround any pathogens in the blood and engulf and then digests them.
Explain how white blood cells help to defend
against pathogens by antibody production
Lymphocytes produce antibodies which are complimentary to the antigens on the outside of the pathogen. They stick to the pathogen preventing it from infecting cells. The antibodies cause pathogens to stick together and make it easier for phagocytes to engulf them.
What are antibodies?
A protein produced by the immune system that attack antigens.
What is the function antitoxins?
They neutralise the toxins produced by pathogens.
What are antigens?
A protein on the surface of a substance (usually a pathogen) that triggers an immune response.
Explain how white blood cells help to defend
against pathogens by antitoxin production
Some pathogens produce toxins which make you feel ill. Lymphocytes can also produce antitoxins to neutralise these toxins. Both the antibodies and antitoxins are highly specific to the antigen on the pathogen
