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Immunity Heroes: Skin, hair, mucus, saliva White Blood Cells:
B-Cells T-Cells Macrophages
Germy Villians: Pathogens:
Bacteria Viruses Microorganisms
Any foreign particle that enters the body is called a PATHOGEN
Usually a bacteria or virus. Comes in many different
forms and attacks the body
ANTIGEN - the part of a pathogen that produces an immune response
NONSPECIFIC IMMUNITY is a defense system that responds immediately to protect the body from all foreign substances, WHATEVER they are…
Nonspecific - the same response works against many different infections Methods:
The Skin (main defense) Mucus membranes The inflammatory response Phagocytosis
The first line of defense is the organ system called the INTEGUMENTARY SYSTEM
This Consists of: The Skin - epidermis Hair – keratin protein Nails – dead skin cells filled with keratin
Often referred to as the most important of our defense systems This is the largest of all body systems
Methods of protection: Acts as a barrier The acid pH of skin inhibit bacteria from growing
From the latin word “integere” which means to
cover
You: “Your epidermis is showing!”
Response: “What! It is?” (meanwhile they are looking around for this so called epidermis…usually at their butt or something)
You think: “Wow this person is dumb, but you decide to play along until they realize it”
Pronounced (Fay-go-sites)
Once invaders make it past the mechanical barriers of our body, phagocytes are the cells that engulf or ingest them
Ex: neutrophils, macrophages
Called phagocytosis: Arm-like extensions pull the
pathogen into a storage organelle
Lysosomes secrete enzymes for breakdown
Broken material is then released
Called Natural Killer Cells (NK Cells) as they kill infected body cells
Yep, these cells can kill cancer cells and virus-infected cells before the immune system does
They are less “picky” They attack by releasing lytic
(cutting) perforin chemicals that slice a target cell’s membrane and nucleus
This is a response to ANY body tissue injury (nonspecific)
Begins with a chemical alarm that releases histamine and kinins: Causing dilation of blood vessels Causing leakage of capillaries Triggering pain receptors Attracting phagocytes (called
chemotaxis)
Increased blood leads to redness Capillary breakage leads to swelling About an hour after, neutrophils
begin to engulf dead cells and pathogens
“Pus” is just a mixture of dead
neutrophils, broken cells, and dead
pathogens
The Immune Response
Immunity – immune comes from the latin word “immun” and means FREE This is our built-in SPECIFIC DEFENSE SYSTEM
Immune Response - third line of defense Involves production of antibodies from immune cells
These cells are called LYMPHOCYTES
Remember… an antigen is a molecule from a pathogen or foreign organism that provokes a specific immune response.
Duality of Immune System
Humoral (Antibody) Immunity Involves production of antibodies
against antigens
Antibodies are produced by certain lymphocytes called B cells B cells that are stimulated will
actively make antibodies
Antibodies are found blood plasma, lymph, mucus and the surface of B cells
Duality of Immune System
Cell Mediated Immunity Involves the production of
lymphocytes called T cells that recognize foreign antigens on the surface of cells Helper T cells
Cytotoxic “Killer” T cells
T cells activate the activity of other cells: B cells, macrophages, neutrophils They are WBC stimulators
The big eater Makros = large Phagein = eater Macrophages are large white
blood cells that eat any pathogen that is foreign or marked with an antibody
They are considered to be phagocytes as they clean up cellular debris by engulfing it
They are attracted to the site of infection by chemicals “smells” given off by dying cells Histamine and kinins
Are they really white?
WHITE BLOOD CELLS or LEUKOCYTES are actually the defenders of the body
Cops in the blood stream… They consist of:
Lymphocytes (B Cells and T Cells) Granulocytes (Neutrophils)
Their goal is to maintain homeostasis White blood cells travel along a different
system of highways in the body called the LYMPHATIC SYSTEM This system transports lymphocytes (B Cells and
T Cells) in the body Consists of the lymph nodes, spleen, and lymph
vessels
The PLASMA B-Cell
B-LYMPHOCYTES are named after their location of creation (the Bone marrow)
One form of B-Cell is the Plasma Cell
On the surface of each Plasma Cell are receptors to recognize foreign antigens These receptors can match only one
antigen
Once B-Cells find a match – they create ANTIBODIES to mark the bacteria or virus
Antibodies
This Y-shaped protein is created by Plasma Cells
It attaches to antigens so the body can identify pathogens…and DESTROY them!
Their main goal is to mark antigens, and signal for help…
Bacteria and other pathogens that are covered in antibodies are more likely to be attacked by cell eating MACROPHAGES
How Antibodies Work?
Antibodies are unique for a specific antigen or foreign body invader
They are “Y” shaped in order to land on the target site and recruit cells to destroy the infection Some act as labels to identify
antigens
Some cause the clumping together of bacteria, to make them less likely to spread
Some B-Cells are smart…
Activated B-Cells are sometimes called MEMORY B-CELLS.
Memory B-cells start producing ANTIBODIES as soon as an antigen comes back
When the pathogen infects again, it is destroyed before any symptoms show
This is like a police dispatcher receiving the same call, and the police station already knowing what to do…
This is why we don’t get the same exact cold twice
The T-Helper Cell
Also called CD4+ cells (for a protein on their surface) These are WBC’s whose primary task is to activate B-Cells and
Cytotoxic T-Cells T-Helper cells are activated by Dendritic Cells And they are like the security guards with walkie talkies… Helps relay chemical messages in order to let the body know that
foreign antigens are present
Cytotoxic “Killer” T-Cells
Also called CD8+ cells (for a protein on their surface) These are specialized white blood cells whose primary task is
to attack our “good” cells that have already been infected T-Helper cells activate Killer T-Cells Infected cells are recognized by antigens on their surface…
1. Bacteria With Antigens on Surface
Macrophage
T cell
B cell
4. B Cells make antibodies that bind to bacterial antigens. This helps other cells identify and destroy bacteria
3. Helper T cells activate B cells
5. Macrophages digest bacteria, and display antigens on their surface
Section 40-2 Immunity
2. Bacterial antigens stimulate B cells
Macrophage
T Cell
Helper T Cell Killer T Cell
Infected Cell
Antigens are displayed on surface of macrophage
T cell binds to activated macrophage
T cell, activated by macrophage, becomes a helper T cell
Helper T cell activates killer T cells and B cells
Killer T cells bind to infected cells, disrupting their cell membranes and destroying them
Immune Response