The Immune System Part I Physiology Standards 10

The Immune System Part I Physiology Standards: 10 a-e Germ Theory and Non-specific defense

The Germ Theory n The germ theory states that: – infectious diseases are caused by microorganisms of different types, commonly called germs – Many believed that sickness and poor health was the work of ‘spirits’ or some ‘higher source’ A disease is any condition that disrupts the normal functioning of the body n A pathogen usually “transmits” the disease to a host Salmonella is a bacterium found on n and in all raw chicken!

Agents of Disease n There are many examples of agents for diseases and they fall into 5 major groups: – Viruses – the most common is influenza known as “the flu” – Bacteria – can either break down cells or release toxins into the organism – Protists – a disease that is often transmitted by an animal like malaria from mosquitoes – Worms – worms use humans as hosts while they act like parasites – Fungi – fungus causes infections in warm, moist places like athlete’s foot E. coli is a bacterium found in raw meat

Agents of Disease n Viruses vs. Bacteria – Both cause disease, but they act in different ways – Viruses: § Take over a cell’s DNA and instruct the cell to “make” more viruses § There is no “pill” to cure a virus, only the body can cure itself – Bacteria: § Either destroy tissue or release poisonous toxins within your body causing illness § You can take antibiotics to cure yourself of a bacterial infection Flu virus

Agents of Disease n Protists – single-celled animals – Protists often have a complex lifecycle where they take a couple of forms before infecting humans – Malaria attacks human red blood cells! n Worms – the “tropical” parasite – Flatworms and roundworms are the cause of many diseases and severe discomfort – Ascaris is a dangerous and common roundworm while tapeworms are common flatworms

Disease Transmission n How do you get sick ? – What are three ways you can acquire a disease? n What are the ways to prevent disease? – Name three things you can do daily to prevent catching a sickness.

Your Immune System n The function of your immune system is to fight infection through the production of cells that inactivate foreign substances or cells n There are two types of defenses: – Non-specific defenses protect against all pathogens equally (the skin is a non -specific defense ) – Specific defenses act like “special soldiers” that are designed to kill a certain type of pathogen (these are the host of white blood cells and other disease fighting cells in your body)

The Immune System n Nonspecific Defense – your “general” defense system against pathogens – The skin is the most important line of defense against nearly all pathogens § The skin is capable of secretions such as oil, mucus, saliva, and tears that create an intolerable environment for many pathogens § Sweat is also a great defense against pathogens!

Skin Structure