4.3.1.6 Human defence systems

What does the non-specific defence system do?

Work to prevent pathogens from entering the body

How does the skin work to prevent pathogens entering the body?

It acts as a physical barrier, produces antimicrobial secretions to kill pathogens and has good microorganisms known as skin flora that competes with the bad microorganisms

How does the nose work to prevent pathogens entering the body?

It has hairs and mucus which prevents particles from entering your lungs

How does the trachea and bronchi work to prevent pathogens entering the body?

Secretes mucus in order to trap pathogens, cilia beat to waft mucus upwards so it can be swallowed

How does the stomach work to prevent pathogens entering the body?

Produces hydrochloric acid that kills any pathogens in your mucus, or food and drink

What does the specific immune system do?

Act to destroy any pathogens which pass through the non-specific immune system to the body

What are the three ways white blood cells act to destroy pathogens?

Phagocytosis (engulfing and consuming pathogens), producing antibodies, producing antitoxins

How does phagocytosis (engulfing and consuming pathogens) protect you?

This destroys the pathogens, meaning they can no longer make you feel ill

How does producing antibodies protect you?

Pathogens have antigens on their surface which a specific complementary antibody can bind to and once antibodies begin to bind to the pathogen, the pathogens start to clump together, so white blood cells can find them easier. If you become infected with that pathogen again, specific complementary antibodies are produced at a faster rate

How does producing antitoxins protect you?

They neutralise the toxins released by the pathogen by binding to them