The Immune System The Immune System Part IPart I

Physiology Standards: Physiology Standards: 10a-e10a-eGerm Theory and Non-specific Germ Theory and Non-specific

defensedefense

The Germ TheoryThe Germ Theory The The germ theorygerm theory states that: states that:

– infectious diseases are caused infectious diseases are caused by microorganisms of different by microorganisms of different types, commonly called types, commonly called germsgerms

– Many believed that sickness Many believed that sickness and poor health was the work of and poor health was the work of ‘spirits’ or some ‘higher source’‘spirits’ or some ‘higher source’

A A diseasedisease is any condition is any condition that disrupts the normal that disrupts the normal functioning of the bodyfunctioning of the body

A A pathogenpathogen usually usually “transmits” the disease to a “transmits” the disease to a hosthost Salmonella is a bacterium found on

and in all raw chicken!

Agents of DiseaseAgents of Disease There are many examples of There are many examples of

agents for diseasesagents for diseases and they and they fall into fall into 5 major groups5 major groups::– VirusesViruses – the most common is – the most common is

influenzainfluenza known as “the flu” known as “the flu”– BacteriaBacteria – can either break down – can either break down

cells or release cells or release toxinstoxins into the into the organismorganism

– ProtistsProtists – a disease that is often – a disease that is often transmitted by an animal like transmitted by an animal like malariamalaria from mosquitoes from mosquitoes

– WormsWorms – worms use humans as – worms use humans as hostshosts while they act like parasites while they act like parasites

– FungiFungi – fungus causes infections – fungus causes infections in warm, moist places like in warm, moist places like athlete’s footathlete’s foot

E. coli is a bacteriumfound in raw meat

Agents of DiseaseAgents of Disease Viruses vs. BacteriaViruses vs. Bacteria

– BothBoth cause disease, but they cause disease, but they act in different waysact in different ways

– Viruses:Viruses: Take over a cell’s DNATake over a cell’s DNA and and

instruct the cell to “make” more instruct the cell to “make” more virusesviruses

There is no “pill” to cure a virusThere is no “pill” to cure a virus, , only the body can cure itselfonly the body can cure itself

– Bacteria:Bacteria: Either destroy tissue Either destroy tissue oror release release

poisonous toxins within your poisonous toxins within your body causing illnessbody causing illness

You can take You can take antibioticsantibiotics to cure to cure yourself of a bacterial infectionyourself of a bacterial infection

Flu virus

Agents of DiseaseAgents of Disease ProtistsProtists – single-celled animals – single-celled animals

– Protists often have a complex Protists often have a complex lifecycle where they take a couple lifecycle where they take a couple of forms before infecting humansof forms before infecting humans

– MalariaMalaria attacks human red blood attacks human red blood cells!cells!

WormsWorms – the “tropical” parasite – the “tropical” parasite– Flatworms and roundworms are Flatworms and roundworms are

the cause of many diseases and the cause of many diseases and severe discomfortsevere discomfort

– AscarisAscaris is a dangerous and is a dangerous and common common roundwormroundworm while while tapewormstapeworms are common are common flatwormsflatworms

Disease Disease TransmissionTransmission

How do you get How do you get sicksick ? ? – What are three ways you What are three ways you

can acquire a disease?can acquire a disease?

What are the ways to What are the ways to preventprevent disease? disease?– Name three things you Name three things you

can do daily to prevent can do daily to prevent catching a sickness.catching a sickness.

Your Immune Your Immune SystemSystem The The functionfunction of your immune of your immune

system is to system is to fight infection fight infection through the production of cells through the production of cells that inactivate foreign that inactivate foreign substances or cellssubstances or cells

There are There are two types of defensestwo types of defenses::– Non-specific defensesNon-specific defenses protect protect

against all pathogens equally (the against all pathogens equally (the skin is a skin is a non-specific defensenon-specific defense ) )

– Specific defensesSpecific defenses act like “special act like “special soldiers” that are designed to kill a soldiers” that are designed to kill a certain type of pathogen (these are certain type of pathogen (these are the host of white blood cells and the host of white blood cells and other disease fighting cells in your other disease fighting cells in your body)body)

The Immune The Immune SystemSystem Nonspecific DefenseNonspecific Defense – your “general” – your “general”

defense system against pathogensdefense system against pathogens– The The skinskin is the most important line of is the most important line of

defense against nearly all pathogensdefense against nearly all pathogens The skin is capable of secretions such as oil, The skin is capable of secretions such as oil,

mucus, saliva, and tears that create an mucus, saliva, and tears that create an intolerable environment for many pathogensintolerable environment for many pathogens

Sweat is also a great defense against pathogens!Sweat is also a great defense against pathogens!

Skin StructureSkin Structure