Immune System

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Warm Up: What is a pathogen? In your lab on Friday, how did you know if an antibiotic/antimicrobial was effective? What is an immune response?

Pathogens A Disease Causing Agent –Viruses –Bacteria –Fungi –Parasites

Human Immune System Body’s way to protect against pathogens Consists of cells and tissues found throughout the body Detect and destroy

Immune Response from the Immune System An immune response is a complex series of specific and non-specific processes involving a range of cells and chemicals in response to a pathogen. system-can-cause-health-challenges

Nonspecific Defenses Do not target specific pathogens

First Nonspecific Defense Prevent Pathogens From Entering Body Skin –Barrier –Oil & Sweat make acidic Mucous Membranes –Line digestive system, nasal passages, lungs, respiratory passages, reproductive tract –Barrier –Chemical Defenses –Cilia

Second Line of Nonspecific Defense: When pathogens break through first line of defense

Nonspecific Responses 1. Inflammatory Response –Suppress infection & speed recovery –Infected/Injured cells release chemicals that cause increased blood flow to area –More blood = more white blood cells to area = better to fight pathogen –More blood = swelling and redness

Nonspecific Responses 2.Temperature Response –Body temperature increases in response to infection (fever) –Slow bacterial growth –High fever dangerous – interrupts normal cell functioning –> 103 dangerous, >105 can be fatal

Nonspecific Responses 3. Proteins –Interferon – protein released by cells infected with viruses, causes nearby cells to resist infection

Specific Defenses When Pathogens Survive First and Second Line of Nonspecific Defenses

Antigen A foreign substance that enters the body Triggers the body to produce antibodies

Antibody Protein, Y-shaped Specific – different for each antigen Lock/Key “tag” antigen White Blood Cells/Killer Cells attracted to tagged cells & kill them Once body has antibodies, they will remain in body for an extended period of time – so more prepared to fight!

White Blood Cells Attack and kill marked pathogens –Neutrophils – engulf pathogen and destroy –Macrophages – Ingest pathogen and kill –Natural Killer Cells – Destroy infected cells by puncturing cell membrane, causing water to rush in and cell to burst