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Transcript of Immune System
The major organs of the immune system, also known as the lymphoid organs, are the tonsils and adenoids, lymph nodes, lymphatic vessels, thymus, spleen, appendix, Peyer's patches, and bone marrow.
Organs involved in
the immune system
1. Surface coverage- This line of defense is made up of non-specific physical and chemical barriers, such as skin and mucous membranes, that prevent pathogens from entering the body.
2. Non-specific responses- In the second line of defense, leukocytes, or white blood cells, travel throughout the body, and will attempt to inhibit or destroy a pathogen should one get past the first line of defense.
3. Specific Responses- The third line of defense is a specific immune mechanism known as antigens that will trigger in the presence of pathogens and foreign objects
The immune system's lines of defense
The body is able to recognize pathogens, which are anything that can produce disease, because cells called B cells have antibodies that act as receptors attached to their surface.
These antibodies are Y shaped proteins that are able to identify and neutralize foreign objects such as pathogens.
The antibodies do so by recognizing antigens, typically a specific part of the pathogen that will bind to certain antibodies, and the antibodies then neutralize the pathogen by coating the outside of it and labeling the pathogen so that other immune responses will target it.
Non-specific defense mechanism
Occurs quickly after the antigen enters the body
Activated by chemical properties of the antigen
The first two lines of defense are considered innate immunity
Examples- cough reflex, stomach acid, tears
Acquired (or adaptive) immunity
Antigen-specific immune response
After an antigen in the body has been recognized and then processed, the immune system created an army of immune cells designed to attack this antigen specifically
The third line of defense is considered acquired immunity
Examples- the body fighting off a disease that it has contracted, such as measles
Innate vs acquired immunity
Active immunity and passive immunity are types acquired/adaptive immunity. They can both be artificially and naturally acquired.
Immunity occurs as a result of contracting a disease from a pathogen
Natural example- antigens enter the body naturally and the body is producing antibodies
Artificial example- antigens injected into the body in a vaccine, the body produces antibodies
Immunity against a certain pathogen occurs without the body having been exposed to the pathogen
Natural example- antibodies passed from the mother to the infant by breast feeding
Artificial example- preformed antibodies in an immune serum are injected into the body
Active immunity vs passive immunity
"Immune System." NIH, National Institute of Allergy and Infectious Diseases. US Department of Health and Human Services, n.d. Web. 20 Apr. 2014.
"The Immune System." The Ohio State University Wexnar Medical Center. Ohio State University, n.d. Web. 20 Apr. 2014.
Muller, Michael. "The Immune System." The University of Illinois at Chicago. The University of Illinois at Chicago, n.d. Web. 20 Apr. 2014.
"Vaccines and Immunizations." Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 11 May 2011. Web. 20 Apr. 2014.
"Introduction to Immunology Tutorial." Introduction to Immunology Tutorial. The University of Arizona, 24 May 2000. Web. 20 Apr. 2014.
"Immune Response." MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine, 30 May 2012. Web. 20 Apr. 2014. <http://www.nlm.nih.gov/medlineplus/ency/article/000821.htm>.
Works cited (cont.)
The purpose of the immune system is to protect the body from disease and infection.
It does do by distinguishing between healthy and non-healthy cells and keeping bacteria, microbes, viruses, toxins and parasites from invading the body.
Humoral Immune Response: The humoral response occurs when B cells recognize pathogens or antigen circulating in the blood or lymph regions. (1) Firstly, the antigens bind to B cells. (2) Next, Helper T cells costimulate B cells. This requires both a costimulator and antigen. (3) B cells then multiply and produce plasma cells which have antibodies with the identical antigen specificity as the antigen receptors of the activated B cells. The antibodies are released and circulate through the body, binding to antigens. (4) The B cells produce memory cells key in future immunity.
Humoral and Cell-mediated Immunity
Cell-Mediated Immunity: This response involves T cells which responds to cells showing Major histocompatibility complex markers, such as tumor or transplanted cells. (1) Self cells showing foreign antibodies bind to T cells. (2) Next, Interleukins costimulate activation of T cells. (3) If MHCI and endogenous antigens are reported on the plasma membrane, T cells multiply which produces cytotoxic T cells. Cytotoxic T cells then destroy cells displaying the antigens. However, it is instead MHCII and exogenous antigens reported on the plasma membrane, T cells multiply but instead produce helper T cells. Helper T cells then release interleukins (and other cytokines), which stimulate B cells to produce antibodies that bind to the antigens and stimulate macrophages to destroy the antigens.
B and T Lymphocytes
Each B-cell has a receptor that connects only one type of antigen. Similarly to T-cells, B-cells that recognize self-antigens are destroyed, so they don’t harm the body’s healthy cells. One difference between T-cells and B-cells is that B-cells can connect to antigens right on the surface of the invading virus or bacteria. T-cells can only connect to virus antigens on the outside of infected cells. Also, B cells are used in Humoral immune response while T cells are involved in cell-mediated response.
Why Antibiotics are Effective Against Bacteria but not Against Viruses
Antibiotics work in one of three ways: They either interfere with the bacteria's ability to repair its damaged DNA, stop the bacteria's ability to produce what it needs to grow new cells, or weaken the bacteria's cell wall until it bursts. They work since the bacteria is it’s own organism. However, Viruses require a host cell which was already a part of the living organism. Antibiotics do not work against a human’s cells, even if they are over-taken by a virus. In addition, viruses easily mutate if new DNA is introduced, which is why one must get a yearly flu shot
How does the body use the immune system to maintain homeostasis?
The Immune system maintains homeostasis by fighting internal illness and keeping the body healthy.
A Brief Description
HIV destroys CD4 cells (T helper cells) — a specific type of white blood cell that helps the body fight disease. As more CD4 cells are killed, the immune system weakens. HIV infections can last for years before progressing to AIDS.
People infected with HIV progress to AIDS when their CD4 count falls below 200 or they experience an AIDS-defining complication. AIDS is a chronic, life-threatening condition caused by the human immunodeficiency virus (HIV).
HIV is a sexually transmitted infection. It can also be spread by contact with infected blood, or from mother to child during pregnancy, childbirth or breast-feeding.
Signs and Symptoms
Primary Infection symptoms, which occur 1-2 months after infection and last approx. one week
Mouth or genital ulcers
Swollen lymph glands, mainly on the neck
Next is Clinical latent infection which lasts 8-10 years. There are no symptoms but HIV remains in the body, however, as free virus and in infected white blood cells
Early symptomatic HIV infection, which follows CLI symptoms include:
Swollen lymph nodes — often one of the first signs of HIV infection
Cough and shortness of breath
Finally, AIDS (acquired immune deficiency syndrome), which occurs 10 years later without treatment, involves:
Soaking night sweats
Shaking chills or fever higher than 100 F (38 C) for several weeks
Cough and shortness of breath
Persistent white spots or unusual lesions on your tongue or in your mouth
Persistent, unexplained fatigue
Blurred and distorted vision
Skin rashes or bumps
About More than 1.1 million people in the United
States have an HIV infection (.6%).
Treatment options Include:
Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
NNRTIs disable a protein needed by HIV to make copies of itself.
Nucleoside reverse transcriptase inhibitors (NRTIs)
NRTIs are faulty versions of building blocks that HIV needs to make copies of itself.
Protease inhibitors (PIs)
. PIs disable protease, another protein that HIV needs to make copies of itself.
Entry or fusion inhibitors
. These drugs block HIV's entry into CD4 cells. .
. Raltegravir (Isentress) works by disabling integrase, a protein that HIV uses to insert its genetic material into CD4 cells.
Multiple sclerosis (MS)
Multiple sclerosis (MS) is a debilitating autoimmune disease where the body damages the myelin sheath around nerve cells through an unwanted immune response. This causes issues in the communication between your brain, spinal cord and other areas of your body. The immune system recognizes the myelin sheath as an illness and attempts to eradicate it.
Signs and Symptoms
Signs and symptoms: The symptoms of MS vary depending on the location of affected nerve fibers.
Symptoms may present as such:
Numbness or weakness in one or more limbs
Partial or complete loss of central vision, usually in one eye, often with pain during eye movement (optic neuritis)
Double vision or blurring of vision
Tingling or pain in parts of your body
Electric-shock sensations that occur with certain head movements
Tremor, lack of coordination or unsteady gait
Approx. 400,000 individuals have MS
There are many treatment options for one with MS:
: Used to reduce inflammation which spikes during a relapse. Plasma exchange (plasmapheresis).
This procedure removes some blood from your body and separates your blood cells from your plasma. Doctors then mix blood cells with a replacement solution and return the blood to your body.
Treatments which slow progress of the disease
These drugs slow the progress of multiple sclerosis, reduce the number of attacks and lessen the severity of attacks.
Glatiramer acetate (Copaxone)
. This medication may reduce the number of MS attacks. Doctors believe that glatiramer acetate works by blocking the immune system's attack on myelin.
. An oral medication given once daily, this works by trapping immune cells in lymph nodes. It may reduce attacks of MS and short-term disability.
. This medication may reduce the number of MS attacks by interfering with the movement of potentially damaging immune cells from your bloodstream to your brain and spinal cord.
. This oral medication reduces attacks and lesions in people with MS.
Ways to treat symptoms
. This medication improves walking speed in some people.
Medications to reduce fatigue.
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