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Anatomy and Physiology 2 Study Guide 3Immune System1. Define the immune system and its 3 lines of defense.- The immune system is the body’s defense system. It protects us against any threat to our body. There are three lines of defense that work together to destroy any threat. These defense lines are divided into two intrinsic defense systems, but they depend on each other. The first system is the innate immune system (non-specfic). This system contains the first two lines of defense: the external membranes (skin, mucosa etc) and the inflammatory system (macrophages, proteins, etc). Both of these lines act within minutes of a threat.  The second system is the adaptive immune system (specific) this is the third line of defense. This system with the T (cellular) and B (humoral) cells is very specific to a certain virus/bacteria. This system takes days to get into action- So the immune system is divided into the innate and the adaptive systems and there are three lines of defense: the external membranes, the inflammatory response, and the specific immunity with B and T cells. 2. Explain how the innate and adaptive systems are intertwined- These systems, one that attacks foreign substances within minutes and one that takes days to weeks to act, are intertwined. When the innate system releases proteins to attack the foreignsubstances, some go to alert cells in the adaptive system of a presence of a foreign substance. So the innate system telling the adaptive system to get ready, that a foreign substance is in the body. Tony Berardi3. What are surface barriers and how do they function as the first line of defense?- The innate system has the first and second line of defense. The first line of defense is all the surface barriers. The skin protects us every day from many foreign substances. The mucus membranes lining our stomach and other organs also secrete chemicals to kill bacteria and toxins, it lines all body cavities that open exteriorly. - A little cut can enable internal innate.- The skin is strong because of a protein called keratin-this serves as a tough hardening barrier to outside substances, and resistant to weak; acids, bases, and pollution. - The mucous membranes line most organs that open to the exterior and secretes protective chemicals: HCL and protein digesting enzymes to kill microorganisms from the stomach, acidity (pH 3-5) of the skin to inhibit bacteria growth, saliva and lacrimal fluids containing lysozymes (kill bacteria), and mucus to trap microorganisms trying to enter. 4. Explain Nonspecific Cellular & Chemical Defense; the second line of defense including: phagocytes, phagocytosis, phagocyte mobilization, and other factors in this line.- This is the second line of defense. When a substance does get past the skin or mucus membranes, our body depends on this to kill pathogens and repair tissue. - First, we have the phagogcytes (2 types) that engulf and confront pathogens. Macrophages are cells that search throughout the body (leaving the bloodstream) for foreign substances and destroy them by engulfing them. We also have the neutrophils, are one of the WBC’s that attack pathogens upon an encounter and when is needed. - Phagocytosis- the phagocyte attaches to the pathogen (microbe), engulfs it via endocytosis (plasma extensions bind) by forming a membrane-lined vacuole around it (or pulling into it), now called a phagosome. Phagosome will fuse with a lysosome (contains strong digestive enzymes) to form a phagolysosome. Then the microbe is killed and digested by lysosome enzymes, leaving a residual body to be removed by exocytosis. Tony Berardi- As you see, first the phagocyte has to bind to the pathogen, so it needs help either with complimentary proteins or a vaccine will help. o Lysosome is one way to destroy the pathogen; others are via o Respiratory burst- which is using free radicals to kill the pathogen, o Our cells can cause potassium (K+) to enter the phagosome cell, which this will raise the pH and activate certain proteins to finish the job. o This is how macrophages work; neutrophils simply secrete defensins that kill the pathogen by piercing the pathogen membrane. Neutrophils are housed in the bone marrow, so they will leave into the blood stream when needed, called leukocytosis. o Neutrophils are mobilized in a certain way: Leukocytosis, Margination, diapedesis,and chemotaxis Leukocytosis- Neutrophils are housed in the bone marrow, so they will leave into the blood stream when needed Margination is when the neutrophil clings to the inner capillary wall. They cling to something called cell adhesion molecules or CAM’s Diapedesis- Then it will flatten and squeeze across the capillary. diapedesis Chemotaxis- Then phagocytes will be attracted by all the inflammatory chemicals that the injured site of the cell release.- Now for the natural killer cells: These are defense cells in the blood and lymph that kill infected cells in the body. Since theadaptive immune system takes a while to take action, these cells will kill infected cells (also cancer) as it can BEFORE the adaptive immune system is activated.  They attack based on if they cannot recognize certain cell-surface receptors that all body cells have—if these cell-surface receptors are lacking, the cell is foreign. Pathogens also have certain sugars on them that the NK cells will recognize.  The NK cells (non-phagocytic) will secrete chemicals to enhance the inflammatory response; they might also simply activate apoptosis in the infected cell, killing it. o Inflammatory response is triggered when the tissues are injuredTony Berardi1. Prevents the spread of damaging agents to nearby tissues2. Dispose of cell debris and pathogens3. Sets repair stageso There are four cardinal signs (redness, heat, swelling, and pain; these may hinder joint movement.5. Describe the responses to injury, reactive hyperemia, and the mechanisms of occlusion training.- Say you cut your finger or get an injury, what happens? The inflammatory response occurs. This is a response to certain chemicals (cytokines) that an injured cell or tissue release. All of these will help in healing.  When injured, the injury site will release histamine (mast cells), prostaglandins, cytokines (attract WBC), which will vasodilate small vessels in the injured area to cause more blood to rush to the site. This will also make the cell more permeable for fluid to leak out; the chemicals will also


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FSU PET 3323C - Study Guide

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