The Immune System

History of Medicine Today Germ Theory Louis Pasteur hypothesizes that disease is caused by small organisms.

History of Medicine Today Germ Theory Louis Pasteur hypothesizes that disease is caused by small organisms. Koch’s Postulates Robert Koch finds 4 conditions that prove a pathogen causes a disease.

History of Medicine Today Germ Theory Louis Pasteur hypothesizes that disease is caused by small organisms. Koch’s Postulates Robert Koch finds 4 conditions that prove a pathogen causes a disease. Antibiotics Sir Alexander Fleming discovers penicillin.

Bacteria don’t grow around mold!!!

History of Medicine Today Germ Theory Louis Pasteur hypothesizes that disease is caused by small organisms. Koch’s Postulates Robert Koch finds 4 conditions that prove a pathogen causes a disease. Polio Vaccine Jonas Salk’s vaccine against polio becomes available. Discontinued in the U.S. in Antibiotics Sir Alexander Fleming discovers penicillin. Polio Comeback! Worldwide efforts increase to vaccinate people against polio.

Pathogens Defined: microorganisms that cause disease –V–Viruses: turn cells into virus making factories –B–Bacteria: prokaryotes that can release toxic chemicals –F–Fungi: pierce cells and absorb the nutrients –P–Protozoans: single cells protista (eukaryotes) –P–Parasites: grow and feed on a host

Pathogens (contd) Some carried by wind, water, direct contact, indirect contact… Some carried by vectors – Vector: object that carries a pathogen – Examples: 1)Malaria – mosquitos carry the protozoan 2)Black Death – carried by flea’s of mice 3)West Nile Virus – carried by birds, but spread by mosquitoes

The Skin 1 st line of defense: physical barrier Oils & sweat destroy some pathogens – Some cells burst – Some cells shrivel

Mucus Membranes Coat the openings of the body – Nose, mouth, ears, eyes, genitals, anus Lined with cilia & sticky fluids to trap pathogens

White Blood Cells Job: Search & destroy Phagocytes: surround & engulf invaders – Phagocytosis (see animation) Lymphocytes: – T cells: destroy infected body cells – B cells: Inactivate invaders

phagocyte bacteria phagocyte

Defense Proteins Antibodies – Proteins made by B cells – Attach to antigens found on surface of cells – How they help: 1) Bind to antigens of pathogen (like handcuffs) – Causes pathogens to clump – Easy targets for phagocytes 2) Weakens the cell membrane of pathogen – Causes them to burst

Interferon – Cell becomes infected by virus – Infected cell releases interferon to neighbors – Healthy cell (right) absorbs the interferon and creates defense enzymes – Healthy cell able to fight virus Defense Proteins Virus RNA New virus Interferon proteins virus

Vaccination Prevents infections (not a cure) Vaccination process – Weakened pathogen is injected – Antigens of pathogen cause your immune system to attack Immune system response: – Production of memory cells (for future infections) – Antibodies bind to antigens (for current infection) Goal: Speed up immune response if you encounter the actual virus

Kobe Kuiz 1)What did Louis Pasteur contribute to our knowledge of medicine? 2)Which part of our immune system coats the openings of the body? 3)Name and describe the two types of lymphocytes. 4)What are antibodies and how do they help keep us from harm? 5)Summarize how vaccines are created. 6)Which pathogen… 1)absorbs nutrients from living tissue? 2)is prokaryotic? 7)Which illness is spread by mice? 8)What is the vector of malaria?