Transcript Immune Responce

THE NATURE OF
DISEASE
Immune System

The immune system of the human body is made up
of:
 Cells
 Molecules
 Organs



that act together to defend the body against foreign
invaders that may cause disease.
The health of the body is dependent on the immune system’s
ability to recognize and then repel or destroy these invaders
It is designed to defend you against millions of bacteria,
microbes, viruses, toxins and parasites that can invade your
body.
PATHOGENS

Pathogens: disease causing agents


Ex. Bacteria, Viruses, Parasites
Pathogens are found in soil,
contaminated water, and infected
animals, including other people
Birth


Before you are born your body is free of
pathogens.
At birth microorganisms establish themselves
on
 your skin
 respiratory system
 urinary system
 reproductive system
 intestinal tract
INFECTIOUS DISEASES


Infectious Diseases: any disease
caused by the presence of a pathogen
in the body
These microorganisms have a
symbiotic relationship with your body…
 However, if you become injured or
weak these same organisms can
become pathogens.

EX. ZOONOSIS: An infectious disease transmissible under
natural conditions between animals and human.
Examples of Infectious Diseases
Disease
Cause
Transmission
Virus
Affected
Organ
System
Skin
Smallpox
Colds
Virus
Respiratory
Direct contact
Influenza
Virus
Respiratory
Droplet
Food
Bacteria Digestive
Poisoning
Rabies
Virus
Nervous
Droplet
Contaminated food
Animal bite
What causes a disease?



Not all disease are caused by pathogens
Example: Hemophilia- recessive allele on the X
chromosome
Pathogens can also cause some cancer
Robert Koch



Robert Koch 1876 discovered that
pathogens caused disease
Studying Anthrax
Would inject it into animals, they
would get sick then he would isolate
the bacteria in their blood and
compare them to the anthrax he
isolated from other victims.
Reservoirs of Pathogens
Living Reservoirs

1.
2.
People often carrier a pathogen and pass it to
others without knowing it
Animals can also pass on the flu or rabies to
humans
Nonliving Reservoirs

1.
2.
Soil contains pathogens such as fungi and
bacteria that can cause food borne illnesses
Water contaminated with human waste contains
bacteria that cause intestinal illnesses
Transmission

Pathogens are transmitted to humans
by:
Direct Contact (Examples to Follow)
 Through an Object



Through the Air


Doorknob, Tabletop, Faucet handle
Coughing and Sneezing
Through an Intermediate Organism

Fleas, Ticks, Mosquitoes, Rats
Transmission

Direct contact


An easy way to catch most infectious diseases is by coming in
contact with someone who has one. This "someone" can be a
person, an animal or, for an unborn baby, its mother.
Person to person.

Most common- direct transfer of bacteria, viruses or other
germs from one person to another. (touches, coughs on or kisses
someone who isn't infected).
Transmission

Animal to person.


Being bitten or scratched by an infected animal can make you
sick and, in extreme circumstances, could even cause death.
Handling animal waste can be hazardous, too. For example,
you can acquire a toxoplasmosis infection by scooping your
cat's litter box, particularly if you're pregnant.
Mother to unborn child.

A pregnant woman may pass germs that cause infectious diseases to
her unborn baby. Germs can pass through the placenta.
Transmission

Indirect contact
Disease-causing organisms can
also be passed along by indirect contact.



Many germs can linger on an inanimate object, such
as a tabletop, doorknob or faucet handle.
You can pick up the germs he or she left behind. If
you then touch your eyes, mouth or nose before
washing your hands, you may become infected.
Some infections occur from organisms that naturally
live in the environment but are not passed from
person to person. Example anthrax.
What Causes a Symptom





Pathogens can over come the defense of your immune
system, they can multiply causing damage to the
tissues.
Viruses can cause death to the cells in which they
invade
Toxins are poisons which can be produced by
microorganisms
The poisons can be transmitted to the blood
Some toxins produce fever, destroy blood cells, and
proteins synthesis
PATTERNS OF DISEASE

Center for Disease Control and
Prevention (CDC):


Government Health Department that
identify pathogens, their method of
transmission, and geographic distribution
Endemic Disease: disease that is
continuously present in the population

Ex. Common cold
Patterns of Disease

Epidemic- widespread outbreak of an

Pandemic- epidemic over a wide geographical
infectious disease; many people are infected
at the same time
area; "a pandemic outbreak of malaria.”
Treating Disease


Antibiotics- produced by microorganisms that in small
amounts will kill or inhibit the growth and
reproduction of other microorganisms
Can be used to cure bacterial infections but does
NOT affect viruses.
Antibiotic Resistance


Think back…
What is antibiotic resistance again?
Immune Response
The Body’s Fight Against
Disease
The Skin
1st line of defense
Acts as a physical barrier
 How do pathogens enter the skin?

Body Secretions


Mucus: traps things entering digestive and
respiratory tracts
Sweat, Tears, Saliva: contain enzyme
lysozyme that help digest cell wall of some
bacteria cells
Inflammation
Occurs at the site of an infection
 Fluid leaks into injured tissue helping to
isolate and destroy pathogens
 Symptoms include redness, swelling, pain,
and heat
 Inflammation begins when damaged tissue
cells and white blood cells called basophils
release histamine.

Histamine




Causes blood vessels in the
injured area to dilate-makes
them more permeable to
fluid.
Dilated BV cause the redness
of the inflamed area.
Fluid leaks out from the
vessels to help destroy toxic
agents.
So what is an antihistamine?
Fever


Fever refers to an elevation in body
temperature.
Normal oral measurement of 98.6 F (37 C)

Body temperature can also vary up to 1 F (0.6 C) throughout the
day.

Fever is not considered medically significant until body
temperature is above 100.4 F (38 C).

Fever serves as one of the body's natural defenses against
bacteria and viruses which cannot live at a higher temperature.

For that reason, low fevers should normally go untreated, unless
accompanied by troubling symptoms.
White Blood Cells (WBC)

White Blood Cells- defend against
pathogens
Phagocytes


White Blood Cells that destroy pathogens by
surrounding them and engulfing them
Phagocytes include macrophages, neutrophils,
monocytes and eosinophils

Macrophages-found in body tissues

Others are found in the blood
Phagocytosis
The Lines of Defense



Macrophages- WBC that provide the 1st line
of defense when pathogens enter the tissues
If they get past the macrophages the next
line is neutrophils
3rd line- Monocytes -immature macrophages
which circulate in the blood
Lines of Defense Cont.



Monocytes can squeeze through blood vessels to the
infected area
Once they reach the infected area they become as
large as mature macrophages and engulf the dead
neutrophils and pathogens
When the infection is over, some monocytes mature
into tissue macrophages that remain in that area to
fend of new infections
PUS
Fluid that forms at site of infection
 Made of dead macrophages and body fluid
 Formation continues until the infection is
over
 Cleared away by macrophages

Questions

What is the immune system?

What does WBC stand for?

What is the function of a WBC?


What are some ways that your body fights
infections?
How can infections be transmitted?
Parasites

An animal or plant that lives in or on a
host (another animal or plant); it obtains
nourishment from the host without
benefiting or killing the host
Where can parasites be found?

Can be found in:
Meat
 Unsanitary areas
 Insects (like mosquitoes)
 Fish
 Snails
 Dogs
 Cats
 HUMANS

roundworms
28 foot tapeworm
**Interesting Facts**



The longest tapeworm ever removed from a human
came out on September 05, 1991.
In all, doctors pulled a 37 foot tapeworm out of a
body through the mouth.
Whale tapeworms can grow up to 120 feet long.
Questions

What is a parasite?

Where can they be found?

What makes them a parasite?