ALS 2304 Week 11: Immunology
ALS 2304 Week 11: Immunology ALS 2304
Popular in Animal Physiology and Anatomy
Popular in Agricultural & Resource Econ
This 7 page Class Notes was uploaded by Mara DePena on Sunday April 10, 2016. The Class Notes belongs to ALS 2304 at Virginia Polytechnic Institute and State University taught by Dr. Cline in Spring 2016. Since its upload, it has received 15 views. For similar materials see Animal Physiology and Anatomy in Agricultural & Resource Econ at Virginia Polytechnic Institute and State University.
Reviews for ALS 2304 Week 11: Immunology
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 04/10/16
ALS 2304 IMMUNOLOGY LYMPHATIC SYSTEM Major function is to remove extra intercellular fluid. It leaks away from capillary beds and causes extracellular fluid. This extracellular fluid is carried away. Ducts drain back towards the heart and pass through lymph nodes. The lymph nodes filter the lymph. If there is an infection, it will go through the lymph node. A series of filters and a high concentration of immune cells exist there. (Highest concentration of immune cells in ileum, second highest in lymph nodes.) You are most apt to pick up bacteria in body in the small intestine because of its brush border, which is exceptionally thin. This layer of epithelial cells has capillary beds on the other side. If it was thicker it would hinder the transport of the nutrients from the lumen into the lympthatic or capillary system. The border tears and you bleed into yourself. The bacteria from the small intestine gains access to the extracellular fluid through these tears, so there is a lot of lymphatic tissue near the small intestine. Second great vascular system of the body. Fat goes back through this system, is filtered, and is then dumped back out. The other two nutrients go to the liver. There is no pump associated with the lymphatic system. The skeletal muscles surrounding the lymphatic vesicles pump lymph towards the heart (inferior venicava). Diaphragm is responsible for returning most of the lymph back towards the heart. Elephantiasis- Parasite bores into lymphatic ducts. If you have something stop up the lymphatic ducts, you get excess lymphatic fluid. LYMPHATIC CELLS Natural killer cells- Immune surveillance. Wander through body at complete random and look for stuff that shouldn’t be there. Attack and destroy bacteria. T lymphocytes (T cells)- Mature in the thymus. Older you get, the more the thymus shrinks. B lymphocytes- Secrete antibodies (very small component of immune system), formed in bone marrow. Macrophages- Cells that participate in phagocytosis. Encounter foreign cells and eat them. Dendritic cells- Participate in endo and phagocytosis. LYMPHATIC TISSUES Red bone marrow- Inside the bone. Forms a large component of the blood. Thymus- Houses lymphocytes and regulates their activity. Lymph nodes- Cleanse lymph. Tonsils- Lymph nodes in rear of oral cavity. Protect against inhaled and ingested pathogens. Spleen- Produces red blood cells in fetus and in newborn baby. Removes old RBC, synthesizes antibodies. NONSPECIFIC RESISTANCE Immune system targets everything that is considered to be foreign. This is the most understood division of the immune system. Many things are all happening simultaneously. First Line of Defense o External barriers Skin Defensins- Proteins, like a bunch of razor blades. Rip open holes in foreign membranes. Lactic acid- Found in oily secretions of skin. From sweat forms the acid mantle that inhibits bacterial growth/replication. Bacteria that is a threat to you competes with your host bacteria for resources. Respiratory cilia- Cilia that line the respiratory system and beat in the upper direction toward the oral cavity. Phlegm traps bacteria you inhale. Urine flush- Cleanses bacteria out of the urinary system. With females, you’re more likely to have a UTI because their urethra is shorter. Lysozyme in tears, mucus, and saliva that destroy bacteria. Mucus on mucous membranes trap bacteria that can then be expelled from the body. Hyaluronic acid- Just below the surface of the skin. If bacteria goes through skin, it will encounter this acid, which inhibits bacterial replication. Bacteria can be trapped here. Like a moat. Very viscous and prevents bacterial migration. When physical barriers fail, white blood cells: o Leukocytes Neutrophil- Most abundant. In connective tissue, kill bacteria. Participate in phagocytosis when they encounter bacteria. Participates in a respiratory burst, commits suicide by absorbing oxygen and reducing it to superoxide anions. Reaction with H to form peroxide and bleach. All of these are very destructive and wipes out everything in the local region (killing zone) in order to destroy bacteria. Eosinophil- Associated with high parasitic loads. Also very high in animals that have allergic responses. Found in mucus membranes, associated with parasites, allergens, and pathogens. Produce superoxide, peroxide, neurotoxins. Neurotoxins target something in the parasite nervous system which the animal does not have in its own. Basophil- Secrete leukotrienes and histamine. These two hormones are released when an invader is encountered. These hormones attract the neutrophils and eosinophils. Lymphocytes- White blood cells. T-cells, B-cells, and natural killer (NK) cells. T cells are most abundant at 80%, then B cells at 15%, then NK cells at 5%. Monocytes- Emigrate from blood into connective tissue. Have the ability to morph into macrophages. Participate in phagocytosis, seek out invading pathogens and destroy them. Antimicrobial Proteins o Interferons- Associated with viruses. High virus load, lots of interferons. From leukocytes infected with viruses. Alert neighboring cells. These cells synthesize proteins that defend from infection by inhibiting replication of the virus. Breakdown of viral genes, inhibition of replication, activate NK cells and macrophages. Immune system will destroy self cells infected with viruses. o Complement- Where we will encounter our first figure associated with the immune system. Made up of 30 proteins that float around in an inactive state in circulation all the time. If you pull the trigger, they participate in the immune system in a big way. Triggered by: o Activation of antibodies o Lectin (sugar) attracted to surface of pathogen o Proteins only found on cell wall of pathogen itself These triggers cause C3 convertase to be turned on. o Activates two proteins: C3a, C5a, which cause inflammation to occur. This increases blood flow in a local region. It brings more of the white blood cells. o Activates C3b Makes other sugars start attaching to pathogen in addition to lectin. If there are more sugars on this pathogen, the immune system is more apt to attack it. Causes activation of C6, C5b, and C7 They clump together into a complex. This complex sticks to the cell wall of the pathogen. Works as a suction cup. Doesn’t do anything by itself, but it attracts a C8 protein. C8 attaches to complex and inserts itself into plasma membrane. Works as shovel, digging a hole into the wall of the pathogen. C8 attracts C9s. Once one is activated it attracts other C9s. They come in and stick themselves all the way through the plasma membrane of this pathogen. Form arch, form circular structure that opens a door in the wall of this invader. Cytoplasm starts to leak out and extracellular fluid starts to leak in, deflating the pathogen. Causes pathogen to destruct. Main thing that kills pathogen is extracellular fluid moving down concentration gradient, causing pathogen to swell up and eventually burst open. (membrane attack complex) Immune Surveillance o Natural killer cells patrol the body. Upon recognition of the foreign cell, they release perforins which form a hole in plasma membrane of the intruder. Release granzymes which enter the foreign cell through the pore, destroy enzymes inside, and induce apoptosis, causing the pathogen to autodestruct. Fever o Initiated by exogenous pyrogens. THIS IS A SHORT ANSWER QUESTION ON THE EXAM. A pyrogen is anything that causes fever. They are components of the bacterial membrane that fall off and circulate up to the hypothalamus. The hypothalamus releases prostaglandin and increases body temperature. This increase in body temperature somewhat impairs the replication of the bacteria. o Pyrogens that come from immune cells are the interleukins and interferons. These also increase body temperature. Inflammation o Attracts white blood cells for destruction. o Limits spread of pathogen. Removes debris leftover from destruction of pathogen. Also increases temperature in local region, encouraging mitosis and initiating tissue repair. If you don’t remove the debris, it will form a mass. o Signs are redness, swelling, heat, and pain. o Makes blood vessels sticky. Inside blood vessels are selectins which move back and forth with currents in blood. When inflammation occurs these selectins essential turn into flypaper. They snag leukocytes and hold them in proximity which allows diapedesis/these white blood cells to migrate through and then destroy the foreign particle. Problem in the brain is that the white blood cells can’t migrate into the nervous system to fight the infection due to the blood brain barrier. WHAT YOU SHOULD DO: Make a little diagram that talks about the membrane attack diagram, all nonspecific things, not blood cell types. ON EXAM: All nonspecific things are going to happen because the pig will scrape itself on a nail. Not connected to digestion. SPECIFIC IMMUNITY/CELLULAR IMMUNITY Aspect we do not really understand. Exceptionally complicated. Immune system is going after some particular viral particle. T lymphocytes directly attack and destroy damaged or foreign cells. o Cytotoxic T cells (natural killer cells) Effectors, attack enemy cells. o Helper T cells Help cytotoxic t cells. o Regulatory T cells Inhibit other T cells, prevent autoimmune disease Breaking mechanism for cellular immunity Poorly understood o Memory T cells Remember past experiences, memory function Antigen Presentation o Antigen- Anything that is foreign. In presentation, it is only a component, like a sugar. o Presenting cells encounter antigen, present it and migrate to lymph nodes. At the lymph nodes it is displayed to T cells. o Every cell has an major histocompatibility complex (MHC) molecule, a protein that works as flypaper. It is freely floating in the cytoplasm. First made, then simply dumped into the cytoplasm. If something is foreign in the cytoplasm, it will get stuck onto the MHC. Eventually it is ejected out of the plasma membrane but remains tethered to the cell to present the antigen. This is a signal to anything that encounters the outside of the cell what is inside of it. o MHC is essentially a flag waved back and forth signaling, “Kill me!” o MHC-1 is on all cells that are nucleated (all cells in mammal, most in bird). Birds don’t have nucleated red blood cell. o MHC-2 is only on antigen-presenting cells such as macrophages, dendritic cells, or B-Cells. o Presentation leads to T cell activation, as it bumps into it at random. On T cell is a TCR and a CD4, which abut against the MHC and the antigen. This alerts the T cell that there is something going on in the cell. CD86 on presenting cell and CD28 on T cell, TCR and CD4 abutting an MHC and antigen turns on the T cell. o If antigen presenting cell was not infected, there would be no antigen, and the T cell would not be activated. o Costimulation prevents attack in absence of enemy. o Once the T cell is activated, it starts proliferation and starts dividing like crazy. They are soldiers fighting against an invasion. There is also a mechanism that causes creation of memory cells. They will remember this and if this antigen is ever encountered again they will become activated very rapidly. o T cell attack- Daughter cell, cytotoxic t cell, does not need CD86. Programmed to attack that antigen any time it encounters it. It will bind to the antigen and encounter a lethal hit. It produces little hypodermic needles and breaks down the membrane of the cell, and produces apoptosis. Wipes out the area. Secretes interferons that inhibit viral replication. Secrete tumor necrosis factor, control cancer. All of us have cancers that pop up all the time. Cytotoxic t cells destroy them. o T cell attack- Helper t cell. Secretes interlukins like crazy. They attract neutrophils and NKC, aspects of nonspecific immunity. Also attract macrophages. Cause B cells to divide like crazy. Also cause mitosis of other T cells. o Humoral immunity- B cells Collection of B cells in body have been there since birth. Each one produces a different antibody, which binds to an antigen. Theoretically, B cells produce antibodies against every antigen you can imagine. Antibodies are produced against self cells, and immune system destroys those B cells. Antigen is floatin around and bumps into B cell. Attaches to antibody, which internalizes. This activates the one particular B cell, which displays the antigen to a helper T cell on the MHC. No CD86, so the cell is not destroyed. Activates helper T cell, which dumps interlukin onto this B cell. This cell is flooded with interlukin and starts dividing like crazy. Daughter cells secrete antibodies like crazy, but are not tethered to cell. They are secreted into circulation loosely. This turns up the concentration of this one particular antibody, flooding the system. May take 7 days or 2 weeks. Doesn’t do anything to help the invasion occurring right then, as it takes to long to turn on the physiology. Antibodies- Defend upon a secondary exposure. As soon as the antigen gets into circulation, the antibodies floating around bind to the antigen. Neutralization- Block pathogenic parts of toxin or virus. (Cover toxic part.) Complement fixation- Change shape of enemy/protein, expose complement-binding sites so it can’t cause the disease. Agglutination- Have two arms, can grab two foreigners at a time and stick them together. Makes it easier for other immune cells to destroy them. Precipitation- Ag-Ab complex fall out of solution.
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'