The Immune System

1. The Immune System T- 1-855-694-8886 Email- [email protected] By iTutor.com

2. O bjective The role of the skin Roles of anti-bodies Phagocytes B-lymphocytes T-lymphocytes Role of vaccines Bacterial and viral infections

3. The Immune System The immune system is the body’s natural defense against disease-causing agents such as bacteria, viruses and parasites. The immune system is made up of a complex and vital network of cells and organs that protect the body from infection . It plays an important role in identifying and eliminating abnormal cells. The  Human I mmune System  is divided into two broad groups : Acquired Immune System Always working to protect the body and does not require any special preparation to stop infection. Innate Immune System Needs to be 'primed' before it can work to its full effectiveness though, and is only really effective after it has seen a possible infective agent before.

4. The Immune System Innate Immunity Acquired Immunity B-Cell Immunity T-Cell Immunity Resistance of skin Destruction of organisms by the acids in the stomach Chemical compounds in the blood Cells called ‘Macrophages’ that ingest foreign objects Consist of B-cells Produce Anti-Bodies Involved with Primary and Secondary response Consists of T-Cells T-Cells are: T helper cells T killer cells

5. Structure and organs of the Immune System The structures of the immune system, detailing the parts of the body that play a role in immunity . These include: The lymphatics Lymph nodes Lymphatic Organs and Structures Thymus Spleen Lymph A fluid containing: Water Sugars Salts Waste White Blood Cells Protein Lymph Vessels Carry lymph within the lymphatic system Lymph capillaries are the smallest of the lymph vessels

6. The Immune system Adenoids Tonsils Thymus Spleen Payer’s Patches Bone marrow Lymph Nodes Lymphatic Vessels Appendix

7. Capillaries Capillaries have thin walls which allow fluid in body tissues to flow between the capillaries and tissues. 7 Fluid in the spaces between tissues is called interstitial fluid Once the interstitial fluid flows into the lymph capillaries it is called lymph Lymphatic trunk Right lymphatic duct or thoracic duct Right subclavian vein (neck) Lymphatic vessel Lymphatic capillary Interstitial fluid Blood stream Structure and organs of the Immune System

8. Lymphatic Vessels Pulmonary capillary network Blood flow Systemic capillary network Lymphatic capillaries Lymph node Lymphatic vessels Lymph flow Lymph node Lymph flow Lymphatic capillaries Structure and organs of the Immune System

9. Lymph Nodes Specialized organs that produce lymphocytes. Filter harmful substances from the tissues. Contain macrophages that devour foreign substances. Lymphocytes produce specialized proteins called antibodies that fight disease. Antigens also fight disease by stimulating an immune response in other cells. 9 Structure and organs of the Immune System Lymph Travels in only one direction. Empties into the right thoracic duct and the lymphatic duct. Lipids are transported from the small intestines to the blood stream by the lymph vessels. Location of major groups of lymph nodes: - Tonsils -Mediastinum -Groin -Neck -Adenoids -Armpit

10. Spleen Largest lymphatic organ located in upper left portion of the abdominal cavity. Filters foreign material from the blood. Destroys old red blood cells Activates lymphocytes Structure and organs of the Immune System Thymus Gland Soft gland with two lobes Larger during infancy and childhood Contains important cells called thymocytes T cells (T lymphocytes provide immunity) Thymosin aids with T cell movement

11. Major Players The major players in the immune system include: Macrophage T cells (helper, cytotoxic, memory) B cells (plasma, memory) Antibodies White Blood Cells – Lymphocytes The  lymphocytes   are of 2 types T lymphocytes B lymphocytes Higher rank officials of the immune system and have a sophisticated mode of action .  Their importance is highlighted by the fact, that an absence of lymphocytes , which occurs in AIDS , leaves the body unprotected from infections and finally leads to early death. 

12. B- lymphocytes   The   B lymphocytes  are present in lymph nodes. Upon finding the relevant antigens get activated and transform themselves to plasma cells. Plasma cells secrete large quantities of antibodies corresponding to the antigen found by the B lymphocytes. These antibodies circulate in blood and attach to all infecting organisms and cells present in the body having the concerned antigen. T- lymphocytes This helps them recognize all the tissues of one’s own body. Their response to an overwhelming infection, is in the form of multiplication of the particular cell family concerned with destruction of the particular foreign antigen. They not only destroy the antibody coated cells but also stimulate activation and formation of plasma cells by B lymphocytes. The T lymphocytes are highly specialized and trained cells, which intelligently tackle infections by recognizing and multiplication of a specific lineage of cells, which perform higher immune functions.

13. Antibodies Antibodies are assembled out of protein chains. There are many different chains that the immune system assembles in different ways to make different antibodies.

14. Antibodies as Receptors Antibodies can attach to B cells, and serve to recognize foreign antigens.

15. Antigens as Effectors Free antibodies can bind to antigens, which “tags” the antigen for the immune system to attack and destroy.

16. Role of antibodies Antibodies released into the blood stream will bind to the antigens that they are specific for. Antibodies may disable some microbes, or cause them to stick together (agglutinate). They “tag” microbes so that the microbes are quickly recognized by various white blood cells.

17. Role of Skin Dead skin cells are constantly sloughed off, making it hard for invading bacteria to colonize. Sweat and oils contain anti-microbial chemicals, including some antibiotics.

18. Role of mucus and cilia Mucus contains lysozymes, enzymes that destroy bacterial cell walls. The normal flow of mucus washes bacteria and viruses off of mucus membranes. Cilia in the respiratory tract move mucus out of the lungs to keep bacteria and viruses out. Nasal mucosa

19. Role of phagocytes Phagocytes are several types of white blood cells (including macrophages and neutrophils) that seek and destroy invaders. Some also destroy damaged body cells. Phagocytes are attracted by an inflammatory response of damaged cells.

20. The not-so-common cold A “cold” is an infection of the mucus membranes of the respiratory tract by a rhinovirus. Over 100 rhinoviruses have been identified, which is one reason why we don’t become immune to “the cold.”

21. Virus vs. Bacteria Colds and influenza are caused by viruses. Viruses are which is a non-living particle that contains genetic material, and hijacks your cells to reproduce. Viruses cannot be “killed” with antibiotics. Rhinovirus Influenza virus

22. Virus vs. Bacteria Bacteria are living organisms that have a metabolism, have DNA, and can reproduce on their own. Bacteria can be killed with antibiotics because these substances target key processes in bacteria, such as production of the bacterial cell wall. E. coli Streptococcus

23. Helping the Immune System Medical science has created to systems for augmenting the human immune system: Antibiotics Vaccines

24. How antibiotics work Antibiotics help destroy bacteria (but not viruses). Antibiotics work in one of several ways: Slowing bacteria reproduction. Interfering with bacterial cell wall formation.

25. How vaccines work Modern vaccines are created from killed bacteria or viruses, or fragments of proteins from these microbes. The proteins are recognized as antigens by our immune systems. This causes a mild immune response. Memory T-cells and B-cells remain ready to fight off the illness if it is encountered again.

26. AIDS AIDS (Acquired Immune Deficiency Syndrome) is caused by an infection by the HIV (Human Immunodeficiency Virus), which attacks and destroys T-helper cells. Because it attacks the immune system directly, finding a vaccine has been difficult. Some drugs can slow down HIV reproduction, but no cure exists yet. Prevention is still the best “cure.”

27. AIDS The HIV virus fools helper T-cells into thinking its proteins are “self,” and so is able to infect the cells that trigger specific immunity. The virus forces T-cells to make more viruses, killing the T-cells when the new viruses burst out.

28. AIDS Prevention HIV is a fragile virus that cannot live outside the human body for more than a few minutes. Preventing HIV spread comes down to preventing exposure to body fluids of an infected person.

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