My AP Biology Thoughts  Unit 4 Cell Communication and Cell CycleWelcome to My AP Biology Thoughts podcast, my name is Jacqueline Sun and I am your host for episode 85 called Unit 4 Cell Communication and Cell Cycle: The Immune System. Today we will be discussing how your body defends itself against infection and stays healthy through the complex yet vital immune system. Segment 1: Introduction to The Immune System The immune system is responsible for fighting off germs and other harmful outside invaders from entering and wreaking havoc on your body Different from all other systems in that it is not a specific cell, tissue, or organ but is rather composed of several different cells, tissues, and organs working in tandem. There are many important components of the immune system that can be divided into two general categories: the innate (or the non specific defense system), and the adaptive (or the specific defense system).

Segment 2: More About The Immune SystemInnate (Nonspecific defense system). As the name suggests, you are born with it and it is automatically activated in the face of threats. Uses physical and chemical barriers, killer cells, and fevers to defend the body Simple Physical Barrier is the first aspect of the innate immune system The skin is the first line of defense. It covers nearly every part of your outside body and acts as a physical barrier and keeps out many harmful microorganisms. As long as the skin is mostly undamaged or unharmed, its defense will hold. Mucous membranes also provide a physical barrier. They line the body cavities that connect the inside of your body to the outside, such as the respiratory and urinary system. The thick viscosity of the mucus aids in preventing the entry of harmful microorganisms. Both of these physical barriers also provide chemical defense. For example, The skin and stomach can secrete acids to kill off invaders. Sweat, which is also secreted by the skin, has antimicrobial proteins to kill bacteria. Enzymes can be found in mucus that perform the same function. So lets say your skin was scraped up. Now your body relies on the second line of internal innate defense. Your body may instigate a fever, send out chemical signals calling for defense from body parts, or cause inflammation. These are just a few of the main tactics the body may use, there are many more.

SO HOW DOES YOUR BODY DETECT WHERE THE INJURY IS AND WHERE TO DEFEND ITSELF. IT uses the... Inflammatory response: A bodily process that uses chemicals to signal to the immune system defenders where the damage to the body is. Utilizes redness, swelling, heat, and pain as signal markers For example, In the event of injury, cells in the connective tissue will send out histamine molecules Causes vasodilation, causing redness and heat, which increases the injured cells metabolic rate so they may repair themselves faster Histamines and other inflammatory molecules will increase the permeability of blood vessels, causing nearby capillaries to release protein ridden fluids that cause swelling. Symptoms like hat and swelling attract immune cells such as phagocytes and lymphocytes to start consuming the invading pathogens

What are the actual lines of defense coming to defend the body from intruders and pathogens? Phagocytes are some of the first defense cells on the scene. Their name is directly translated to “to eat” and they indiscriminately consume invaders. Neutrophils are the first type of phagocytes. THey are the most abundant types of white blood cells and after eating a pathogen will self destruct. They are released by injured skin cells in a process known as leukocytosis. Macrophages are the bigger phagocytes and often the second line of defense. They are white-blood cells that have occupied tissues and organs. Some will freely move around and consume intruders, while others remain bound to the tissue or organ and defend against intruders. Unlike neutrophils,...