THE NATURE OF THE NATURE OF DISEASEDISEASE

Immune SystemImmune System The The immune system immune system of the human body is made of the human body is made

up of: up of:  CellsCells MoleculesMolecules Organs Organs

that act together to defend the body against foreign that act together to defend the body against foreign invaders that may cause disease. invaders that may cause disease.

The health of the body is dependent on the immune The health of the body is dependent on the immune system’s ability to recognize and then repel or destroy system’s ability to recognize and then repel or destroy these invadersthese invaders

It is designed to defend you against millions of bacteria, It is designed to defend you against millions of bacteria, microbes, viruses, toxins and parasites that can invade microbes, viruses, toxins and parasites that can invade your body.your body.

PATHOGENSPATHOGENS

Pathogens: disease causing agentsPathogens: disease causing agents Ex. Bacteria, Viruses, Parasites Ex. Bacteria, Viruses, Parasites

Pathogens are found in soil, Pathogens are found in soil, contaminated water, and infected contaminated water, and infected animals, including other peopleanimals, including other people

BirthBirth Before you are born your body is free of Before you are born your body is free of

pathogens.pathogens.

At birth microorganisms establish At birth microorganisms establish themselves on themselves on your skinyour skin respiratory systemrespiratory system urinary systemurinary system reproductive systemreproductive system intestinal tract intestinal tract

INFECTIOUS DISEASESINFECTIOUS DISEASES

Infectious Diseases: any disease Infectious Diseases: any disease caused by the presence of a caused by the presence of a pathogen in the bodypathogen in the body

These microorganisms have a These microorganisms have a symbiotic relationship with your symbiotic relationship with your body…body…

However, if you become injured or However, if you become injured or weak these same organisms can weak these same organisms can become pathogens.become pathogens.

EX. ZOONOSIS: EX. ZOONOSIS: An infectious disease An infectious disease transmissible under natural conditions between transmissible under natural conditions between animals and human.animals and human.

Examples of Infectious Examples of Infectious DiseasesDiseases

DiseasDiseasee

CauseCause Affected Affected Organ Organ SystemSystem

TransmissionTransmission

SmallpoSmallpoxx

VirusVirus SkinSkin DropletDroplet

ColdsColds VirusVirus RespiratorRespiratoryy

Direct contactDirect contact

InfluenzInfluenzaa

VirusVirus RespiratorRespiratoryy

DropletDroplet

Food Food

PoisoniPoisoningng

BacterBacteriaia

DigestiveDigestive Contaminated Contaminated foodfood

RabiesRabies VirusVirus NervousNervous Animal biteAnimal bite

What causes a disease?What causes a disease? Not all disease are caused by pathogensNot all disease are caused by pathogens

Example: Hemophilia- recessive allele on the X Example: Hemophilia- recessive allele on the X chromosomechromosome

Pathogens can also cause some cancerPathogens can also cause some cancer

Robert KochRobert Koch Robert Koch 1876 discovered Robert Koch 1876 discovered

that pathogens caused diseasethat pathogens caused disease

Studying AnthraxStudying Anthrax

Would inject it into animals, they Would inject it into animals, they would get sick then he would would get sick then he would isolate the bacteria in their blood isolate the bacteria in their blood and compare them to the anthrax and compare them to the anthrax he isolated from other victims.he isolated from other victims.

Reservoirs of PathogensReservoirs of Pathogens

Living Reservoirs Living Reservoirs 1.1. PeoplePeople often carrier a pathogen and pass it to often carrier a pathogen and pass it to

others without knowing itothers without knowing it

2.2. AnimalsAnimals can also pass on the flu or rabies to can also pass on the flu or rabies to humanshumans

Nonliving Reservoirs Nonliving Reservoirs 1.1. SoilSoil contains pathogens such as fungi and contains pathogens such as fungi and

bacteria that can cause food borne illnessesbacteria that can cause food borne illnesses

2.2. WaterWater contaminated with human waste contaminated with human waste contains bacteria that cause intestinal contains bacteria that cause intestinal illnesses illnesses

TransmissionTransmission

Pathogens are transmitted to Pathogens are transmitted to humans by:humans by: Direct Contact Direct Contact (Examples to Follow)(Examples to Follow)

Through an ObjectThrough an Object Doorknob, Tabletop, Faucet handleDoorknob, Tabletop, Faucet handle

Through the AirThrough the Air Coughing and SneezingCoughing and Sneezing

Through an Intermediate Organism Through an Intermediate Organism Fleas, Ticks, Mosquitoes, RatsFleas, Ticks, Mosquitoes, Rats

TransmissionTransmission Direct contactDirect contact

An easy way to catch most infectious diseases is by coming An easy way to catch most infectious diseases is by coming in contact with someone who has one. This "someone" can in contact with someone who has one. This "someone" can be a person, an animal or, for an unborn baby, its mother. be a person, an animal or, for an unborn baby, its mother.

Person to person.Person to person. Most common- direct transfer of bacteria, viruses or other Most common- direct transfer of bacteria, viruses or other

germs from one person to another. (touches, coughs on or germs from one person to another. (touches, coughs on or kisses someone who isn't infected).kisses someone who isn't infected).

TransmissionTransmission

Animal to person.Animal to person. Being bitten or scratched by an infected animal can Being bitten or scratched by an infected animal can

make you sick and, in extreme circumstances, could make you sick and, in extreme circumstances, could even cause death. Handling animal waste can be even cause death. Handling animal waste can be hazardous, too. For example, you can acquire a hazardous, too. For example, you can acquire a toxoplasmosis infection by scooping your cat's litter box, toxoplasmosis infection by scooping your cat's litter box, particularly if you're pregnant. particularly if you're pregnant.

Mother to unborn childMother to unborn child.. A pregnant woman may pass germs that cause infectious A pregnant woman may pass germs that cause infectious

diseases to her unborn baby. Germs can pass through the diseases to her unborn baby. Germs can pass through the placenta. placenta.

TransmissionTransmission Indirect contactIndirect contact

Disease-causing organisms can Disease-causing organisms can also be passed along by indirect contact. also be passed along by indirect contact.

Many germs can linger on an inanimate object, Many germs can linger on an inanimate object, such as a tabletop, doorknob or faucet handle. such as a tabletop, doorknob or faucet handle.

You can pick up the germs he or she left behind. You can pick up the germs he or she left behind. If you then touch your eyes, mouth or nose before If you then touch your eyes, mouth or nose before washing your hands, you may become infected. washing your hands, you may become infected.

Some infections occur from organisms that Some infections occur from organisms that naturally live in the environment but are not naturally live in the environment but are not passed from person to person. Example anthrax.passed from person to person. Example anthrax.

What Causes a SymptomWhat Causes a Symptom Pathogens can over come the defense of your Pathogens can over come the defense of your

immune system, they can multiply causing immune system, they can multiply causing damage to the tissues.damage to the tissues.

Viruses can cause death to the cells in which they Viruses can cause death to the cells in which they invadeinvade

Toxins are poisons which can be produced by Toxins are poisons which can be produced by microorganismsmicroorganisms

The poisons can be transmitted to the bloodThe poisons can be transmitted to the blood

Some toxins produce fever, destroy blood cells, Some toxins produce fever, destroy blood cells, and proteins synthesisand proteins synthesis

PATTERNS OF DISEASEPATTERNS OF DISEASE Center for Disease Control and Center for Disease Control and

Prevention (CDC):Prevention (CDC): Government Health Department that Government Health Department that

identify pathogens, their method of identify pathogens, their method of transmission, and geographic distributiontransmission, and geographic distribution

Endemic Disease:Endemic Disease: disease that is disease that is continuously present in the population continuously present in the population Ex. Common cold Ex. Common cold

Patterns of DiseasePatterns of Disease

EpidemicEpidemic- - widespread outbreak of an widespread outbreak of an infectious disease; many people are infectious disease; many people are infected at the same time infected at the same time

PandemicPandemic- - epidemic over a wide epidemic over a wide geographical area; "a pandemic outbreak geographical area; "a pandemic outbreak of malaria.”of malaria.”

Treating DiseaseTreating Disease Antibiotics- produced by microorganisms that in Antibiotics- produced by microorganisms that in

small amounts will kill or inhibit the growth and small amounts will kill or inhibit the growth and reproduction of other microorganismsreproduction of other microorganisms

Can be used to cure bacterial infections but does Can be used to cure bacterial infections but does NOT affect viruses. NOT affect viruses.

Antibiotic ResistanceAntibiotic Resistance

Think back…Think back… What is antibiotic resistance again?What is antibiotic resistance again?

Immune ResponseImmune Response

The Body’s Fight Against The Body’s Fight Against DiseaseDisease

The SkinThe Skin

11stst line of defense line of defense Acts as a physical barrier Acts as a physical barrier How do pathogens enter the skinHow do pathogens enter the skin??

Body SecretionsBody Secretions

Mucus: traps things entering digestive Mucus: traps things entering digestive and respiratory tractsand respiratory tracts

Sweat, Tears, Saliva: contain enzyme Sweat, Tears, Saliva: contain enzyme lysozyme that help digest cell wall of lysozyme that help digest cell wall of some bacteria cellssome bacteria cells

InflammationInflammation

Occurs at the site of an infectionOccurs at the site of an infection Fluid leaks into injured tissue helping to Fluid leaks into injured tissue helping to

isolate and destroy pathogensisolate and destroy pathogens Symptoms include redness, swelling, Symptoms include redness, swelling,

pain, and heatpain, and heat Inflammation begins when damaged Inflammation begins when damaged

tissue cells and white blood cells called tissue cells and white blood cells called basophils release histamine.basophils release histamine.

HistamineHistamine Causes blood vessels in the Causes blood vessels in the

injured area to dilate-injured area to dilate-makes them more makes them more permeable to fluid.permeable to fluid.

Dilated BV cause the Dilated BV cause the redness of the inflamed redness of the inflamed area.area.

Fluid leaks out from the Fluid leaks out from the vessels to help destroy vessels to help destroy toxic agents.toxic agents.

So what is an So what is an antihistamine?antihistamine?

FeverFever

Fever refers to an elevation in body Fever refers to an elevation in body temperature. temperature.

Normal oral measurement of 98.6 F (37 C) Normal oral measurement of 98.6 F (37 C) Body temperature can also vary up to 1 F (0.6 C) throughout Body temperature can also vary up to 1 F (0.6 C) throughout

the day.the day.

Fever is not considered medically significant until body Fever is not considered medically significant until body temperature is above 100.4 F (38 C). temperature is above 100.4 F (38 C).

Fever serves as one of the body's natural defenses against Fever serves as one of the body's natural defenses against bacteria and viruses which cannot live at a higher bacteria and viruses which cannot live at a higher temperature. temperature.

For that reason, low fevers should normally go untreated, For that reason, low fevers should normally go untreated, unless accompanied by troubling symptoms.unless accompanied by troubling symptoms.

White Blood Cells (WBC)White Blood Cells (WBC)

White Blood Cells- defend against White Blood Cells- defend against pathogenspathogens

PhagocytesPhagocytes White Blood Cells that destroy pathogens by White Blood Cells that destroy pathogens by

surrounding them and engulfing themsurrounding them and engulfing them

Phagocytes include macrophages, neutrophils, Phagocytes include macrophages, neutrophils, monocytes and eosinophilsmonocytes and eosinophils

Macrophages-found in body tissuesMacrophages-found in body tissues

Others are found in the bloodOthers are found in the blood

PhagocytosisPhagocytosis

The Lines of DefenseThe Lines of Defense Macrophages- WBC that provide the 1Macrophages- WBC that provide the 1stst line line

of defense when pathogens enter the tissuesof defense when pathogens enter the tissues

If they get past the macrophages the next If they get past the macrophages the next line is neutrophilsline is neutrophils

33rdrd line- Monocytes -immature macrophages line- Monocytes -immature macrophages which circulate in the bloodwhich circulate in the blood

Lines of Defense Cont.Lines of Defense Cont. Monocytes can squeeze through blood vessels to Monocytes can squeeze through blood vessels to

the infected areathe infected area

Once they reach the infected area they become Once they reach the infected area they become as large as mature macrophages and engulf the as large as mature macrophages and engulf the dead neutrophils and pathogensdead neutrophils and pathogens

When the infection is over, some monocytes When the infection is over, some monocytes mature into tissue macrophages that remain in mature into tissue macrophages that remain in that area to fend of new infectionsthat area to fend of new infections

PUSPUS

Fluid that forms at site of infectionFluid that forms at site of infection Made of dead macrophages and body Made of dead macrophages and body

fluidfluid Formation continues until the infection Formation continues until the infection

is overis over Cleared away by macrophagesCleared away by macrophages

QuestionsQuestions What is the immune system?What is the immune system?

What does WBC stand for?What does WBC stand for?

What is the function of a WBC?What is the function of a WBC?

What are some ways that your body fights What are some ways that your body fights infections?infections?

How can infections be transmitted?How can infections be transmitted?

ParasitesParasites

An animal or plant that lives in or on An animal or plant that lives in or on a host (another animal or plant); it a host (another animal or plant); it obtains nourishment from the host obtains nourishment from the host without benefiting or killing the hostwithout benefiting or killing the host

Where can parasites be Where can parasites be found?found?

Can be found in:Can be found in: MeatMeat Unsanitary areasUnsanitary areas Insects (like mosquitoes)Insects (like mosquitoes) FishFish SnailsSnails DogsDogs CatsCats HUMANSHUMANS

28 foot tapewormroundworms

**Interesting Facts****Interesting Facts** The longest tapeworm ever removed from a The longest tapeworm ever removed from a

human came out on September 05, 1991.human came out on September 05, 1991.

In all, doctors pulled a 37 foot tapeworm In all, doctors pulled a 37 foot tapeworm out of a body through the mouth.out of a body through the mouth.

Whale tapeworms can grow up to 120 feet Whale tapeworms can grow up to 120 feet long.long.

QuestionsQuestions

What is a parasite?What is a parasite?

Where can they be found?Where can they be found?

What makes them a parasite?What makes them a parasite?