1. KEY CONCEPT Germs cause many diseases in humans.
The first lines of defense against invading pathogens are the body’s nonspecific defenses (it doesn’t matter what is invading the body, the body will attack it)

2. Viruses, bacteria, viroids, and prions can all cause infection.
1 nanometer (nm) = one billionth of a meter
100 nm
eukaryotics cells 10, ,000 nm
viroids nm
viruses nm
prokaryotics cells ,000 nm
prion 2-10 nm 2

3. Fungi, protists, invertebrates also cause infection

4. Different pathogens cause common infectious diseases.

5. Pathogens can enter the body in different ways.
person-to person contact
breathing in infected air
animal bite
contaminated water
contaminated food

6. Many body systems protect you from pathogens.
Many other tissues and systems help the immune system.
Skin is a physical barrier to infection. It releases sweat, oils, and waxes.
Mucous membranes trap pathogens entering the body. Secretes mucus (sticky fluid that traps pathogens)

7. Many body systems work to produce nonspecific responses.
Nonspecific responses are the same for every pathogen.
In inflammation, blood vessels become leaky.
white blood cells move toward infection and damaged tissue
capillary wall
extracellular space
white blood cell
characterized by swelling, redness, and pain
includes chemical messengers such as histamines (increase blood flow to area)

8. The Inflammatory Response occurs
If blood vessels are damaged – platelets & proteins clot the blood
Chemicals releases, attract white blood cells to engulf pathogens
platelets
fibrin
white blood cell
red blood cell
blood vessel
clot

9. Fever – sign that the body is fighting an infection.
In fever, body temperature increases.
Low fevers stimulate white blood cells to mature.
High fevers can cause seizure, brain damage, and even death.

10. Organs of the immune system
Bone marrow – soft material found inside long bones
Makes red & white blood cells & platelets
Thymus – behind heart
- WBC’s mature here; develop ability to recognize specific pathogens
Lymph Nodes – found in neck, arm pit, groin (“swollen glands”)
- Filter pathogens from lymph (extra-cellular fluid), contain WBC’s
Spleen – behind stomach
- Filter & clean lymph of cell fragments and abnormal tissue, contain WBC’s

11. Cells and proteins fight the body’s infections.
White blood cells attack infections inside the body.
Phagocytes engulf and destroy pathogens.
T cells destroy infected cells.
B cells produce antibodies.

12. Cells of the immune system produce specific responses.
Specific immune responses begin with the detection of antigens.
Antigens are surface proteins on pathogens.
Each pathogen has a different antigen.
virus
antigens

13. Immunity
Being resistant to a specific pathogen
Active immunity:
Being infected and survive
vaccination
Passive immunity occurs without an immune response:
1. mother’s milk
2. Genetics
3. Blood transfusion

14. Allergies occur when the immune system responds to harmless antigens.
An allergy is an response to a harmless antigen.
Allergies are caused by allergens.
Allergens are antigens that cause an allergic reaction.
Allergens cause inflammation responses. (allergy symptoms)

15. There are many different allergens.
food, e.g. peanuts, milk, wheat, etc.
airborne, e.g. pollen, dust mite feces, mold, etc.
chemical, e.g. nickel, medicine, bee stings, etc.

16. Allergens can cause anaphylaxis.
Anaphylaxis is an extreme inflammation response.
Blood vessels and airways become too porous.
If not treated immediately, anaphylaxis can cause death.

17. In autoimmune diseases, white blood cells attack the body’s healthy cells.
Autoimmune diseases are failures of the immune system.
White blood cells cannot recognize healthy cells.
White blood cells attack healthy body cells.
Tissues fail because of attack.

18. There are over 60 autoimmune diseases.