1. Our Body’s Defense System
Immune System:
Our Body’s Defense System

2. THE ROLE OF THE IMMUNE SYSTEM
The Immune System is a collection of structures and processes within the body that prevent bacteria and pathogens from entering.
If a bacteria or virus get into our body  Our immune system detects and eliminates it.
When viruses and bacteria eliminate and damage anything that was able to reproduce it starts to cause problems.

3. Defenses of the body 1st Defense
Skin –tough, outer layer, Protects body from pathogens, is oily/acidic
Our skin secretes anti-bacterial substances which prevent us from waking up with mold on us!
2nd Defense
Mucous Membranes
Act as a barrier to pathogens/microbes trying to enter the body- Mucus traps microbes and sweeps them away
Line all internal surfaces exposed to the outside (lungs,nose, etc)

4. D.O.T.B. continued… 3rd Defense Inflammatory Response Mast cells:
Search for unknown proteins
When found- Histamines released(make blood vessels more permeable, thus signaling inflammation)
4th Defense –WBC’S
Inflammation brings in Leukocytes/WBC’s
Move through circulatory system open gap in cell wall to reach pathogen (Diapedesis)

5. D.O.T.B. continued… Phagocytosis:
Is when an immune cell known as a phagocyte ingests and kills invading organisms (phagocytes=neutrophils, eosinophils, dendritic cells, macrophages)
The following WBC’s circulate in the blood stream awaiting chemical signals of invasion or inflammation
Neutrophils-kill invading microbes, die shortly after
Eosinophils-kill cells of invading parasites and bacteria
Macrophages-kill invading pathogens,detects changes in normal cells (cancer), don’t die after englufing pathogens

6. D.O.T.B. continued…..
Natural killer cells- destroys other human cell who present antigens to indicate their infection, “cell homicide”
-binds to infected cell and secretes membrane dissolving enzymes
Dendritic Cells- Engulf pathogens and carry information about them back to the spleen and lymph nodes. ( link innate------acquired immune system)
Help us to better fight pathogens both in the present and the future.

7. LEUKYOCYTES/WBC’s
If pathogens get past the skin and mucous membranes, as well as triggers an inflammatory response, the WBC’s then takes over the role of protecting the body.
They do so by ingesting foreign chemicals and cellular debris, , by destroying infectious agents and cancer cells, or by producing antibodies.
Leukocytes , Lymphocyte , Monocytes, Granulocytes, B-cells, Plasma cells
WBC’S INCLUDE: T-cells, Helper T-cells, Killer T-cells, Suppressor T-cells, Natural killer cells, Neutrophils, Eosinophils, Basophils, Phagocytes, Macrophages

8. ANTIBODIES Highly specialized proteins produced by B-cells
Swarm the invader and make it more difficult for them to function
Act as “Tags” by marking the invaders to be destroyed and sending signals to phagocytes
produced by plasma cells, Y shaped
Each respond to specific antigen
Antibody --> binds to toxin= antitoxin (When toxin is venom= antivenin)
Binding- disables the chemical action of the toxin
A large number of antibodies binds to an invader, this signals the complement system that the invader must be removed.

9. Complement system
Complement system Series of proteins Each sensitive to specific antigen Proteins in complement system are floating freely in blood Proteins here are manufactured in liver Complement proteins - cause lysing (bursting) of cells and signal to phagocytes that a cell needs to be removed

10. LYMPH NODES
Small, bean shaped structures (part of the lymphatic system) Contain filtering tissue and large number of cells
Blood transfers food, water, and oxygen to lymph through capillary walls and lymph carries to the cells
-absorbs proteins and wastes produced by cells and carries them away
Lymph- clear fluid within the lymph nodes that carries those cells to different parts of the body. (bathes cells with water and nutrients)
When the body is fighting infection lymph nodes enlarge and feel sore because the cells and bacteria in them are swelling

11. SPLEEN THYMUS Largest lymphatic organ in the body
Contains white blood cells, which fight infection and disease
Helps control the total volume of blood in the body
Dipose’s of old or damaged blood vessels, old RBC’s recycled in spleen,platelets and WBC’S are stored
***Filters blood looking for foreign cells
THYMUS
Play a vital role in T cell maturation
Located behind breast bone
Vital to babies, adults can have theirs removed

12. BONE MARROW Yellow tissue in the center of the bones
Assists the immune system by producing B-cell’s
Produced new blood cells
Rbc- fully formed in marrow then enter blood stream
WBC - mature elsewhere

13. LYMPHOCYTES
Attack specific pathogens the body already knows, help your body avoid infection
Two different types: T-cells and B-cells
T-CELLS
Mature in the Thymus Gland
Help destroy infected/cancerous cells
Helper T cells- do not kill pathogens, but they activate and direct the cells that do
B-CELLS
Originate and mature in bone marrow
B cells- make antibodies to attack bacteria and toxins

14. ANTIBODIES Highly specialized proteins produced by B-cells
Swarm the invader and make it more difficult for them to function
Act as “Tags” by marking the invaders to be destroyed and sending signals to phagocytes
produced by WBC, Y shaped
Each respond to specific antigen
Antibody --> binds to toxin= antitoxin (When toxin is venom= antivenin)
Binding- disables the chemical action of the toxin
A large number of antibodies binds to an invader, this signals the complement system that the invader must be removed.

15. Complement system
Complement system Series of proteins Each sensitive to specific antigen Proteins in complement system are floating freely in blood Proteins here are manufactured in liver Complement proteins - cause lysing (bursting) of cells and signal to phagocytes that a cell needs to be removed

16. Quick Quiz What is our immune systems first line of defense?
What triggers the body’s inflammatory response?
What is the role of the helper T cells? How would their absence affect the bodies ability to overcome pathogens?
What is the role of the phagocytes in the immune system? What is phagocytosis?
What cell produces Antibodies? Why are they sometimes reffered to as “tags”?

17. Helpful links: https://www.youtube.com/watch?v=CeVtPDjJBPU