Immune System

Immune System- defends the body against pathogens

→ex: bacteria, viruses, tumors, parasitic worms, fungi, protozoa

First line of defense:

non-specific response- The body is aware that something foreign is in the body, but not exactly what it is

specific response- The body knows what is wrong & uses specialized cells and antibodies to fight it

Non-Specific Response:

mast cells – cells that produce histamine when

they think that the body is being invaded

histamine- causes redness, swelling, and mucus

production. Allergies are caused by the release

of histamine when it is not needed

Phagocytes (white blood cells)- recognize surface proteins on pathogens called antigens and destroy them.

Macrophages- Phagocytes that engulf and

destroy pathogens as well as dead cell remains

*If phagocytes cannot overcome a pathogen, specialized immune cells called lymphocytes get involved

Specific Response:

Plasma B cells- recognize antigens on foreign

invaders and create antibodies.

Antibodies-proteins that

attatch to antigens and help

destroy pathogens

Memory B Cells- cells that “ remember” certain

antigens and can react quickly in response to a

future exposure.

Helper T Cells- cannot kill directly, but

help by activating B cells.

Killer T Cells (Cytotoxic T cells)- destroy virally

infected cells and tumor cells.

*Symptoms of illnesses are not a result of the pathogen, but rather the immune system attempting to get rid of the pathogen

Antibiotics- only kill bacteria, not viruses

Vaccine- a weakened form of a disease that

makes the body produce antibodies and activates

B Cells.

Antibody- Y-shaped molecule produced by plasma cells when exposed to pathogens

Virus- Consists of protein coat & nucleic acid core