Download The Immune System - San Diego Unified School District

Adv Biology 1-2
The Immune System
 The immune system protects against pathogens.
 Pathogen-any disease causing agent.
Nonspecific Immunity
 Nonspecific immunity deals with all pathogens the
same.
 Includes parts of other systems.



Epidermis (outer layer of skin) prevents entry and is
constantly replaced.
Mucus in the lungs traps pathogens.
Acids in the stomach, vagina and bladder damage pathogens.
Nonspecific Immunity cont’d
 Macrophages and
white blood cells “eat”
pathogens.
 Swallow and digest
them with enzymes.
Nonspecific Immunity cont’d
 Damaged cells release histamine.
 Causes blood vessels to widen.
 Area is flooded with fluid, white blood cells and
macrophages.
 Pathogens and damaged cells are eaten.
Nonspecific Immunity cont’d
 A fever is an attempt to kill a pathogen by breaking
down its proteins.
 The hypothalamus in the brain (regulates
temperature) increases body temperature.
Specific Immunity
 Specific immunity responds to pathogens individually.
 Some is provided at birth (passive immunity).
 The rest come from exposure (active immunity).
Specific Immunity cont’d
 White blood cells are made in bone marrow.
 B cells mature in the bone marrow.
 T cells mature in the thymus (in the chest).
Specific Immunity cont’d
 Pathogens contain antigens.
 Antigen-anything that initiates an immune response.

Part of the cell wall or something they produce.
Specific Immunity cont’d
 There are many types of B cells (but only a few of
each).
 Antigens bind to a specific B cell or T cell.
 The body then mass produces the necessary B or T cell.
Specific Immunity cont’d
 B cells produce antibodies (a protein that binds to a
specific antigen).
 Macrophages then eat the pathogen.
 Some B cells become memory cells.


Remember what antibody to make later.
Later infections are dealt with faster.
Specific Immunity cont’d
 T cells attack viruses and fungi.
 Macrophages swallow a pathogen and presents its
antigens to a helper T cell.
 Helper T cells stick to the antigen, activating killer T
cells.
 Killer T cells stick to the pathogen and cut it up.
Antibiotics
 Antibiotics are chemicals for curing bacterial
infections.
 Most attack peptidoglycan in the cell wall.

Cause the cell wall to fall apart and the bacteria to explode.
 Others interfere with transcription or translation.
Vaccines
 A vaccine is a harmless or dead virus given to help the
body develop a response.
 The body responds without getting really sick (or dying)
and memory cells are produced.
 Later infections are dealt with faster and with fewer
symptoms.