2 1 defense against infectionPresentation Transcript
Do Now Take out your homework and lets go over it
Objective: How doesthe body defendagainst infection?
Function of the Immune System:The Immune system guards the entire body against infection
YOUR IMMUNE SYSTEM HASTWO DEFENSE SYSTEMS NONSPECIFIC DEFENSE SPECIFIC DEFENSE
Nonspecific Defense Can act against a wide variety of pathogens
First line ofnonspecific defense Skin – barrier around almost entire body Saliva – contain enzymes that destroy bacteria cell wall Mucus – traps pathogens in nose and throat Tears – contains enzymes that destroy bacteria cell wall Stomach – secretions and acid destroy pathogensNonspecific defenses can act on wide range of pathogens
Second line ofnonspecific defenses Inflammatory response 1. Infected area becomes red and painful (why?) 2. HISTAMINES are secreted and blood and fluid flow to area is increased More white blood cells More fluid Increase temperature
The specific defense Distinguishes between “self” and “other” Inactivate or kill any foreign substance or cell that enters body Respond to SPECIFIC pathogensNon specific will respond to any pathogen
Recognizing the invaders1. When the immune system recognizes pathogens as “others” it uses cell and chemical weapons to attack them2. The immune system REMEMBERS the invader3. Immune memory enables a faster response if the pathogen happens to infect the body againKEY IDEA: The recognition andmemory is called the IMMUNERESPONSE
Regents Review Which statement best describes an immune response?1. It always produces antibiotics.2. It usually involves the recognition and destruction of pathogens.3. It stimulates asexual reproduction and resistance in pathogens.4. It releases red blood cells that destroy parasites.
Antibodies Proteins produced by the WHITE BLOOD CELLS of the immune system that mark/label invaders to be killed Since they are proteins, what is an important physical feature? Have specific BINDING SITES that recognize the invaders VERY SPECIFIC – WHY?
ANTIGENS ANY FOREIGN SUBSTANCE ON THE OUTSIDE OF FOREIGN MATERIAL THAT CAN STIMULATE AN IMMUNE RESPONSE They are typically located on the outside of bacteria, viruses, or parasites
KEY IDEA!!! ANTIBODIES recognize ANTIGENS on PATHOGENS Antibodies mark pathogens to be targeted based on their antigens Let’s draw it
Regents Review The immune system of humans may respond to chemicals on the surface of an invading organism by1. releasing hormones that break down these chemicals2. synthesizing antibodies that mark these organisms to be destroyed3. secreting antibiotics that attach to these organisms4. altering a DNA sequence in these organism
Imagine you are at aYankee/Met game… How do you know what type of fan someone is? Pathogen = Antigen =
Immune system response The immune system responds to antigens by 1. Increasing the number of cells that attack the invader 2. Increasing the number of cells that produce ANTIBODIES Antibodies LABEL antigens for destruction by immune cells Antibodies have specific shapes for specific antigens
Regents Review Which phrase does not describe a way the human body responds to fight disease?1. destruction of infectious agents by white blood cells2. production of antibodies by white blood cells3. increased production of white blood cells4. production of pathogens by white blood cells
Regents Review Which substances may form in the human body due to invaders entering the blood?1. nutrients2. vaccines3. antibodies4. red blood cells
Regents Review Which statement does not identify a characteristic of antibodies?1. They are produced by the body in response to the presence of foreign substances.2. They may be produced in response to an antigen.3. They are nonspecific, acting against any foreign substance in the body.4. They may be produced by white blood cells.
What are lymphocytes? Main cells of the immune system – search for antigens B lymphocytes (B cells) Discover antigens in body fluids T lymphocytes ( T cells) have antigens presented to them by infected cells or by immune cells with antigen encounters Both are made in the BONE MARROW B cells mature in the bone marrow; T cells mature in the thymus
B and T Lymphocytes Each each B and T cell are only capable of recognizing ONE specific antigen