IMMUNE SYSTEM ATTACK AIM: What are pathogens and how do they threaten homeostasis? How do white blood cells launch an immune response?

Homeostasis- maintaining a stable internal environment that allows living things to function normally. Loss of homeostasis= sickness/disease Unable to regain homeostasis= death

Pathogen-

Pathogen- a foreign microorganism that enters the body and causes harm “AKA” Foreign microorganism Pathogenic microorganism Microbe Foreign microbe Disease-causing agent

Examples of Pathogens?

Virus, Bacteria, Yeast, Fungus, and other Parasites.

How do we fight pathogenic microorganisms that enter our bodies? Recognize the threat Attack the threat (Antigen/Antibody) Remember the threat RAAAR!!!

Immune System Purpose of the immune system is to recognize “self” vs. “non self”

Immune System Cells…

White blood cells

Immune System Cells… White blood cells – B Cells – T cells

Recognize PathoGENS have antiGENS on their surface Antigens are molecules that the immune system reads to recognize invaders (like an ID card) An antigen is any molecule that can trigger an immune response

Recognize Special white blood cells called B cells are able to recognize antigens on pathogens in the blood If a B cell recognizes a dangerous antigen, it will attach an antiBody to the antiGEN The antibody is a flag, signal, or mark that says DESTROY THIS CELL!!!!!

Remember…

pathoGENS have antiGENS The BODY makes antiBODIES

The B cell antibody that attaches to the antigen fits like a LOCK AND KEY Each B cell is designed to fit JUST ONE antigen.

ATTACK A pathogen with an antibody attached to its antigen is marked for killing It will be…

ATTACK A pathogen with an antibody attached to its antigen is marked for killing It will be engulfed, or eaten by other white blood cells.

ATTACK A pathogen with an antibody attached to its antigen is marked for killing It will be engulfed, or eaten by other white blood cells.

ATTACK part 2 If a pathogen sneaks past the B cells in the blood, it may be able to get inside a cell. Once a pathogen enters a cell, the only way to kill the pathogen is to kill the cell too! Special white blood cells called T cells destroy cells that pathogens have invaded

REMEMBER The single B and T cell designed to fight the pathogen will multiply into an army of millions After the attack is over, the millions of extra cells will remain in the body forever as memory cells.

REMEMBER The millions of memory cells will be ready to recognize and attack this pathogen if it ever invades again. This pathogen can never harm the body again. The host is now immune to the pathogen.

You work in a store. Last week a man came in and robbed you. He took almost all of your money and got away. The police had to search for a couple of days, but they finally found the robber. Two week later, the robber broke out of jail. He walks into your store again and you recognize him. What do you do as soon as you recognize the robber? Why are you more prepared this time? Do you think that you can stop the robber before he gets away this time? Compare this situation to how the immune responds to a pathogen the second time.

How do vaccines work?? A vaccine is a substance that makes someone immune to a certain pathogen. If this pathogen ever enters the body, it will be destroyed before it can cause harm to cells. What do you think is in the vaccine???

Vaccines Vaccinations use a weakened version of the microbe, or pieces of the pathogen to give the immune system a “sneak peak” of the invader. The immune system recognizes the injected antigens, and will prepare an army of B and T cells. If a living, pathogenic version enters the body, the immune system is now prepared to attack.

You have heard that one day this week, someone is going to rob the store that you work in. You have many customers each day, and you have no idea who it will be. Luckily, there is a snitch that is going to show you a picture ID with the robbers face. Would this make you more prepared to face the situation? Do you think this could help you stop the robber from robbing the store? If you recognized the robber when they entered the store, what would you do to stop the situation? Describe how this situation might be similar to a patient receiving a vaccine.