Download BODY DEFENSES AND DISEASE

BODY DEFENSES
AND DISEASE
The 5th Guy
CAUSES OF DISEASE
Noninfectious Disease
 When you have a disease, your
normal body functions are
disrupted.
 Noninfectious disease ARE
NOT spread from person to
person
 CAUSES:
 Smoking
 Lack of physical activity
 High-fat diet
CAUSES OF DISEASE Infectious
Disease
 Infectious disease CAN be passed
from one living thing to another.
 CAUSED BY:
 Pathogens: virus, microorganism
or other organisms that cause
disease.
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PATHWAYS TO PATHOGENS
 AIR: Some pathogens travel through the air
*Example: a single sneeze
 CONTAMINATED OBJECTS: If you share
objects with an infected person, you can
become SICK!
*Example: contaminated
doorknobs,
keyboards, combs, and
towels
 PERSON TO PERSON: Some pathogen
are spread by direct person
*Example: kissing, shaking hands or
PATHWAYS TO PATHOGENS
 ANIMALS: Some pathogens are carried by
animals
 Example: humans can get a fungus called
ringworm from handling an infected dog.
 FOOD AND WATER: Drinking water in the
United States is generally safe. But water
lines can break allowing germs to enter.
 Bacteria growing in foods and beverages can
cause illnesses
 Example: meat, fish, and eggs that are
not cooked enough
PUTTING PATHOGENS IN
THEIR PLACE
PASTEURIZATION
 During the mid-1800s, Louis Pasteur discovered
that microorganism cause wine to spoil.
 Pasteur devised a method of using heat to kill
most of the bacteria in wine and milk.
VACCINES AND IMMUNITY
 In the late 1700s, no one knew what a pathogen
was.
 Edward Jenner studied a disease called
smallpox.
 He observed that people who had been infected
with cowpox seemed to have protection against
smallpox.
PUTTING PATHOGENS IN
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THEIR PLACE
ANTIBIOTICS
 Have you ever had strep throat?
 An antibiotic is a substance that can
kill bacteria or slow the growth of
bacteria
 Viruses, such as those that cause
colds, are not affected by antibiotics.
 Antibiotics can kill only living things.
 A virus is NOT a living thing.
Vaccines

A substance prepared from
killed or weakened pathogens.

How could a vaccine prevent the
spread of disease?

Stimulates the body to produce
immunity.

How is being vaccinted similar to
being infected with a disease?

Used to trigger the body to make
memory cells for a specific
pathogen

How is it different?
YOUR BODY’S DEFENSES
FIRST LINE OF DEFENSE
 For a pathogen to harm you, it must
attack a part of your body.
 YOUR BODY’S FIRST LINE OF
DEFENSE IS YOUR SKIN!
 Your skin is made of many layers of fat
cells. The outermost layers are dead.
 As a result, many pathogens that land
on your skin have difficulty finding a
live cell to infect
YOUR BODY’S DEFENSES
FAILURE OF THE FIRST LINES OF DEFENSE
 Sometimes, skin is cut or punctured
and pathogens can enter the body.
 THE BODY ACTS QUICKLY!
 Blood flows to the injured area
 Cell parts in the blood called
platelets, which help seals the
wound.
 The increased blood flow also brings
cells that belong to the IMMUNE
SYSTEM.
CELLS OF THE IMMUNE
SYSTEM
 The immune system consists mainly
of three kinds of cells.
MACROPHAGE
BIG EATERS
 Engulf and digest microorganisms or
viruses.
 If only a few microorganism or viruses
have entered a wound, the
macrophages can easily STOP
THEM.
 It alerts the rest of the immune
system of invaders
CELLS OF THE IMMUNE
SYSTEM
Lymphocytes - T cells and B cells
On the surface of each lymphatic cell are receptors that
enable them to recognize foreign substances. These
receptors are very specialized - each can match only one
specific antigen.
Helper T Cell
Helper T cells are the major driving force and the main
regulators of the immune defense. Their primary task is to
activate B cells and killer T cells. The killer T cell is
specialized in attacking cells of the body infected by
viruses and sometimes also by bacteria. It can also attack
cancer cells.
CELLS OF THE IMMUNE
SYSTEM
B Cells

The B lymphocyte cell searches for antigen
matching its receptors. If it finds such antigen it
connects to it, and inside the B cell a triggering
signal is set off.

The plasma cell is specialized in producing
specific protein, called an antibody, that will respond
to the same antigen that matched the B cell
receptor. Antibodies are released from the plasma
cell so that they can seek out intruders and help
destroy them.
Challenges to the Immune
System

Allergies – over reaction to foreign
antigens that are not dangerous to
most people. (ex. Peanuts,
penicillin, mold, etc.)

Cancer – a group of diseases in
which cells divide at an
uncontrolled rate. (ex. Skin
cancer)

Immune Deficiency – HIV/AIDs;
specifically infects the T-cells.

Auto-immune Diseases – cells
mistake body cells for foreign
antigens; ex rheumatoid arthritis

What is the differenece between
an allergy and an autoimmune
disease?

In an autoimmune disease, the
immune system attacks the body’s
own cells. In an allergy, the
immune system reacts to foreign
cells that are for the most part
harmless; such as pollen, foods or
medicine.