Transcript The Lymphatic and System and the Immune System

The Immune System
Small Pox
A white blood cell eating bacteria.
Slide # 2
The Immune System
1. The immune system is
a defense system
against foreign invaders
(pathogens)
2. Immune system
consists of a variety of
different types of white
blood cells (WBC’s)
White blood cell eating
bacteria
Slide # 3
The SKIN: The First Line of Defense
1. The skin is the most important
first line of defense
a. Top layer is dead cells;
prevents pathogens from
entering
b. Sweat & tears have enzymes
that prevent bacterial growth
2. Mucus that lines the nose, throat,
& lungs traps pathogens
3. Pathogens and mucus are swept
into stomach where stomach
acids destroy them
Layers of Skin
Slide # 4
Inflammatory Response: Second line of Defense
1. Nonspecific response to a localized infection.
2. Injured or infected cells cause blood vessels to
enlarge so they can leak fluid & WBC’s
a. skin appears red at injury site
b. swelling occurs around infection
3. Macrophages (large WBC’s are first to arrive)
a. Nonspecific: treat all pathogens the same
b. Consume (eat) dead cells & pathogens
4. Fever kills pathogens. Fever over 103°F is
dangerous for humans.
White blood cell chasing a bacterium cell
Click on the picture to watch!
Slide # 6
The Inflammatory Response
Skin
Wound
Phagocytes move into the
area and engulf the bacteria
and cell debris
Bacteria enter
the wound
Capillary
Slide # 7
The Immune Response: Vocabulary
1. Immunity: capacity of the human body to resist
specific pathogens by identifying foreign (non-self)
antigens
2. Antigen: anything that causes an immune response
3. Lymphocytes: WBC’s involved in immunity and the
immune response
a. Helper T cells, B cells, & Killer T cells
b. are specific; seek out & destroy specific
pathogens
4. Immune Response: specific response to a infection
that has spread through body triggered by the
presence of antigens/pathogens
Slide # 8
The Immune Response: The Third
and Final Line of Defense
1. Macrophages ingest pathogen; send out chemical
signal to call Helper T cells to the site of infection
2. By the time Helper T cells arrive, macrophages have
incorporated pathogen’s antigens onto its own cell
membrane
3. Helper T cell attaches to antigens on macrophage &
develops new binding site that recognizes foreign
antigens (copies enemy’s information)
4. Helper T cell passes information to two different
attack cells: B cells & Killer T cells
Slide # 9
Immune Response
Macrophage
T cell binds to
activated
macrophage
Helper T cell activates
killer T cells and B cells
Helper
T Cell
Killer
T Cell
T Cell
Antigens are
displayed on
surface of
macrophage
T cell, activated by
macrophage, becomes
a helper T cell
Infected Cell
Killer T cells bind to
infected cells,
disrupting their cell
membranes and
destroying them
Slide # 10
Killer T Cells: Have Direct Contact with Antigens
1. Killer T cells come into direct contact w/ a cell;
pierces hole in cell wall
a. Water moves into the cell & the cell swells &
bursts open
2. Killer T cells produced at same time as B cells
3. Killer T cells destroy protists, virus infected cells, &
cancer cells
Slide # 11
B Cells Produce Antibodies
1. B cells release antibodies
2. Millions of B cells are cloned &
millions of antibodies are released
into blood when fighting infection
3. Antibody: Y shaped protein that
“tags” an antigen for destruction
4. Antibodies also bind to virus &
bacterial toxins & neutralizes
them
Antigenbinding
sites
Antigen
Antigen
Antibody
Antibody
Slide # 12
Active vs. Passive Immunity
1. Passive Immunity is acquired when antibodies
to the antigen are injected into the body. They
do not last. (Ex. Breast milk)
2. Active immunity is produced when the body
creates its own antibodies after being exposed
to an antigen.
– Acquired through vaccinations
– Acquired through infection of pathogen.
– Antibodies are constantly produced by
memory cells created when the body was first
infected.
Antibody Concentration
Why you don’t get chicken pox twice.
Interval
between
exposures
First
exposure
Second
exposure
Time
Slide # 14
Immune System Disorders/Problems
1. An allergy is a disorder in which the immune
system overreacts to the presence of an
antigen such as pollen.
2. An autoimmune disease is one in which the
immune system attacks its own body cells.
Ex. M.S. and Arthritis
3. Rejection of organ transplants (cells are
foreign).
4. Cancer cells are naturally destroyed by the
body; however, when the body fails to
recognize them they spread causing
tumors.
Cells of the Immune System
The body's innate defense against disease is natural
immunity. The immune system consists of white blood
cells, cell products, and other substances.
Cells of the Immune System
1. Lymphocytes include:
a. T cells (T for thymus, where they mature)
b. B cells (B for bone marrow, where they originate)
c. Natural killer (NK) cells (less abundant)
2. Macrophages & Granulocytes: Phagocytic or "cell-eating”
a. Neutrophils -- form an early line of defense against bacterial
infections (Non-specific response) & involved in inflammatory response
b. Eosinophils -- Their natural role is to defend us against parasites;
also release chemicals that damage lungs and contribute to asthma
c. Basophils -- involved in inflammatory response & allergic
reactions
d. Mast cells settle in connective tissues and usually do not circulate in
the blood stream. Release histamine; contributes to allergic
reactions
Mast cell with
Salmonella bacteria