Your Immune System Chapter 31. 1-3

You need to know Germ theory is the idea that certain microscopic particles may cause diseases. Pathogen – disease causing agent There are different types of pathogens that cause many different kinds of disease. Pathogens can enter the body in different ways.

5 Main Pathogens Bacteria – single-celled organisms. Release chemicals that are toxic. Can destroy healthy body cells. (Food Poisoning) Viruses – disease-causing strands of DNA and RNA surrounded by protein coats. Take over healthy cell and make more viruses. Fungi – multicellular or single. Piercing healthy cells and take the cells nutrients. (Athlete’s foot)

Common Bacterial Pathogen – E. Coli Food borne illness that can cause many gastrointestinal issues. Reproduces very quickly, so not much is needed to cause infection. A Viral Pathogen – Zika Virus A relatively ‘new’ and unknown virus that is connected to the increased incidences of microcephaly of children Common Fungal Pathogen –Cryptococcus Found in soil in subtropical/tropical regions. Know to cause infections to skin, soft tissue, lymph nodes, and bone.

5 Main Pathogens Protozoa – single-celled organism that preys on other cells. (Malaria) Parasites – organisms that grow and feed on a host. Some kill the host and others just drain the body of nutrients.

Common Parasitic Pathogen – Malaria This is a small living organism that is causing issues in other organisms by producing toxins or chemicals that may be affecting the infecting tissue Common Protazoan Pathogen – Giardia muris Intestinal parasite found in rodents, birds and reptiles.

Entering the Body Pathogens can enter the body directly or indirectly. Some pathogens are spread by surviving on non-living sources and then entering the body. Some spread through vectors, or, anything that carries a pathogen and transmits it into healthy cells.

Our Protection The immune system is the body system that fights off infection and pathogens. It includes different “layers” of protection. Your skin is the first line of defense. It’s a physical barrier. It’s oily and sweaty so it can kill some pathogens. Your eyes, nose, ears, mouth, excretory organs have a mucus membrane and cilia to protect you as well.

White Blood Cells If pathogens get past your outer defenses, you use specialized cells to attack those pathogens. White blood cells find and kill these pathogens. There are six specialized white blood cells, all have a particular job. If a WBC eats another cell it’s called a phagocyte.

Lymphocytes After the phagocytes, lymphocytes reach the infection. Two kinds of lymphocytes are T cells and B cells. T cells destroy infected body cells B cells produce proteins that inactivate pathogens that have not yet infected a cell.

3 Proteins of Immune System Complement proteins – weaken pathogen’s cell membrane. Antibodies – destroy pathogens in a few ways: Bind to pathogen’s membrane proteins. Cause pathogens to clump together. Activate complement proteins. Interferons – prevent virus from entering healthy cells.

Immunity Passive Immunity – immunity that occurs without the body’s reaction, you are just born with it. Active Immunity – immunity that your body produces in response to a specific pathogen that is attacking your body. Acquired immunity is when the body doesn’t get sick from the same disease. This is considered a Specific immune response

Immune Response Chapter 31.3-.5

How your body responds Some body systems respond non-specifically This means the body will respond the same way no matter what kind of pathogen it is. The immune system produces specific responses This means you have special cells that are created to fight off a particular pathogen.

Non-Specific Inflammation Fever This where an affected area turns red, swells, itches, becomes painful and increases temperature. This provides more space for white blood cells to work as well as histamines opening up vessels. Fever This stimulates to production of interferons and helps to stop viruses from spreading. Remember: Skin and Mucous membranes are non-specific

Specific Specific immune defenses lead to acquired immunity and they occur at a cellular level. Antigens – are markers on the surface of cells and viruses that help the immune system identify them Memory cells – are specialized T and B cells that remember an antigen that has already been in the body.

Tissue Rejection You don’t always want foreign cells in your body, but when you do, you want to make sure they don’t get attacked by your body. This is called tissue rejection and is caused by the protein markers on the new cells causing an immune response.

Controlling Pathogens Keeping an area clean is the best protection Heat and chemicals (antiseptics) can kill pathogens (soap, rubbing alcohol, vinegar) Antibiotics – medicines that target fungi or bacteria. Antibiotic resistance means there are newer strands of bacteria/fungi that can survive attacks from antibiotics.

Vaccines Vaccines work to prevent infection, not stop an infection while it’s occurring. We insert the antigen of a pathogen into the body and your immune system reacts and remember that specific antigen. This makes your immune system capable of fighting off that disease the next time it comes around.

Overreactions Allergy – Is an oversensitivity to a normally harmless antigen. Allergens are what we call those antigens. When these allergens are recognized, histamines are released (this causes inflammation). This inflammation isn’t just unnecessary, but dangerous.

Allergens Food allergens – reactions to antigens found in specific foods (affects 2/100 adults) Anaphylaxis – is when airways swell up and vessels to become porous. Airborne allergens – allergens that are breathed in (usually pollens). Sometimes pet dander and saliva can cause this as well. Chemical allergens – metals (nickel) fairly common. These could be based on genetics or environmental factors (like overexposure to something)

Autoimmune Diseases This is when the body’s immune system attacks its healthy cells. More than 60 autoimmune diseases. (Some can be acquired through pathogens, but many are linked to genetics) Common ones include: Rheumatoid arthritis Type 1 Diabetes Hashimoto’s thyroiditis Multiple sclerosis (MS)