Transcript 31.2 Immune System

31.2 Immune System
KEY CONCEPT
The immune system is a body system that fights
infection and prevents illness.
31.2 Immune System
Many body systems protect you from pathogens.
• Many other tissues and systems help the immune system.
– Skin: Physically block pathogens from entering the
body.
– Mucous membranes: Found in the nose and throat;
Traps particles before they enter.
– The circulatory system: Transports cells of the immune
system.
31.2 Immune System
Cells and proteins fight the body’s infections.
• White blood cells attack infections inside the body.
– Phagocytes: Cell that engulfs and destroys pathogens.
– T cells: Destroys infected body cells.
– B cells: Produces antibodies.
31.2 Immune System
• Three types of proteins fight off invading pathogens.
– Complement proteins weaken pathogen membranes.
– Antibodies: Protein that causes pathogens to clump or
become ineffective.
– Interferon: Proteins that stop viruses from reproducing.
antibody
pathogens
31.2 Immune System
Immunity prevents a person from getting sick from a
pathogen.
• In all immunity, pathogens are destroyed before you get
sick.
• Passive immunity occurs without
an immune response.
Passed through:
– mother’s milk
– genetics
• Active immunity is gained after
the body undergoes a specific
immune response.
31.2 Immune System
BOTH
• Prevent future illness if the body becomes infected!
• Lytic Infection is an infection pathway in which the host
cell bursts, releasing the new viral offspring into the
host’s system, where each then infects another cell.
• In a Lysogenic infection, a phage combines its DNA into
the hosts cell’s DNA.