Unit 3 (Chapter 13) The Lymphatic System and Immunity Presented by Dawn Duran, PT, MHS, CSCS Adjunct Professor, Kaplan University

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The Lymphatic System

Lymphatic System The Lymphatic System is actually a specialized component of the circulatory system. It serves the body by returning excess interstitial fluid to the blood, absorbing fats and fat-soluble vitamins from the digestive system and transporting them to the venous circulation, and serving as a defense mechanism against invading organisms and disease. These functions assist the body to maintain fluid balance and provide immunity, which is essential to well-being. The lymphatic system is an important component in maintaining homeostasis.

The Lymphatic System Lymph is a specialized fluid formed in the tissue spaces that is transported by way of specialized lymphatic vessels to eventually reenter the circulatory system Lymph flow in the body only moves TOWARD the heart. A special x-ray procedure using a dye to illustrate the flow of lymph is called a lymphangiogram

The Lymphatic System Lymphatic Vessels – transport lymph into the circulatory system. They are similar to veins except that they have thinner walls, contain more valves and have lymph nodes located at intervals along their course. Cisterna chyli serve as a storage pouch for lymph as it moves towards its entry into the venous system. The lining of lymphatic vessels allows for movement of materials into and out of the vessels. The epithelium is simple squamous. Lymphatic vessels in the walls of the small intestine are called lacteals.

The Lymphatic System Lymph Nodes – are small rounded or bean-shaped masses of lymphatic tissue surrounded by a capsule of connective tissue. They are part of the lymphatic system, which carries fluid (lymph fluid), nutrients, and waste material between the body tissues and the bloodstream. Functions of the lymph nodes include Defense Production of white blood cells (WBC) Filtration of lymph

The Lymphatic System At birth there are between 600-700 lymph nodes present in the average human. Although these nodes can increase or decrease in size throughout life, any nodes that have been damaged or destroyed, do not regenerate Lymph nodes may be found singly or in groups, and they may be as small as the head of a pin or as large as an olive. Groups of lymph nodes can be felt in the neck, groin, and underarms. Lymph nodes generally are not tender or painful. Most lymph nodes in the body cannot be felt. Cancer cells that have left their original site travel first to nearby lymph nodes. For this reason lymph nodes play an important role in the detection and treatment of cancer

Lymph Nodes Knowing the distribution of lymph nodes is important in knowing the possible route of infection or the path that cancer cells may follow as they move through the body.

Lymph Nodes How are lymph nodes examined? You can palpate (or feel) lymph nodes to check if they are swollen or tender Lymphadenopathy – refers to swollen lymph nodes Lymphadentitis – inflammation of the lymph nodes

The Lymphatic System Role of Lymphatics in fluid homeostasis Fluid from blood plasma that is not reabsorbed by blood vessels drains into lymphatic vessels. Lymphatic drainage prevents accumulation of too much tissue fluid

The Lymphatic System

The Lymphatic System Right lymphatic duct: drains lymph from the right upper extremity and right side of the head, neck, and upper torso into the right subclavian vein. Thoracic duct is the largest lymphatic vessel in the body. Drains lymph from about ¾ of the body (ie the majority of the body) into the left subclavian vein to be returned to the heart. It collects most of the lymph in the body (except that from the right arm and the right side of the chest, neck and head, which is collected by the right lymphatic duct) and drains into the systemic (blood) circulation at the left subclavian vein

The Lymphatic System Whereas the circulatory system is a closed system that relies on the heart for circulation, the lymphatic system is not a closed system. Therefore, it must rely on valves in the vessels, skeletal and smooth muscle action, respiratory movements, and pressure gradients to circulate the lymph.

Lymphatic Flow Lymph enters a node by way of four afferent lymph vessels. When passing through the node, lymph is filtered so that injurious particles such as bacteria and cancer cells are removed and prevented from entering the blood and circulating all over the body. Lymph exits a node via a single lymph vessel.

The Lymphatic System Thymus It is a small lymphoid tissue organ located in the mediastinum It is largest at puberty and shrinks/atrophies as you get older. This process is called involution. In the older adult, the remaining tissue is replaced by fat. The thymus secretes a group of hormones collectively called thymosin, which is vital to the body’s T-cell development and the immune system Produces T-lymphocytes that are critical to the functioning of the immune system

The Lymphatic System Tonsils Masses of lymphoid tissue/lymph nodes located in the mouth and back of the throat Help protect against bacteria The tonsils function as the first outpost of the body’s immune defense system at the portal of easiest entry for germs into the body - the mouth Three sets of tonsils: Palatine Pharyngeal Lingual

Tonsils Palatine tonsils – located on each side of your throat These are the tonsils usually removed during tonsillectomy Pharyngeal tonsils (also called adenoids, especially when swollen) – located near the posterior opening of the nasal cavity Lingual tonsils – located near the base of the tongue.

The Lymphatic System Spleen Located in the upper left quadrant of the abdomen Spleen – largest lymphoid organ in the body It serves as a reservoir for blood that can be returned to the circulatory system when needed Functions also include phagocytosis of bacteria and old RBCs Has a very rich blood supply (ie it is highly vascularized) The spleen filters the blood protecting the body against foreign organisms and removing old red blood cells

The Lymphatic System Describe the following diseases of the lymphatic system: Lymphangitis Lymphedema Elephantiasis Lymphoma Tonsillitis Splenomegaly

The Lymphatic System Lymphangitis a bacterial infection in the lymphatic vessels which is characterized by painful, red streaks below the skin surface Lymphedema is a collection of fluid that causes edema (swelling) in the arms and legs Causes: removal of lymph nodes (d/t cancer treatment), medication, radiation and injury to the lymph nodes Treatment for lymphedema depends on its cause and includes wearing compression garments such as stockings or sleeves, proper diet and skin care, and fluid drainage. Elephantiasis Elephantiasis is a condition characterized by gross enlargement of an area of the body, especially the limbs. Other areas commonly affected include the external genitals. Elephantiasis is caused by obstruction of the lymphatic system, which results in the accumulation of a fluid called lymph in the affected areas True elephantiasis is the result of a parasitic infection caused by three specific kinds of round worms Elephantiasis is most commonly found in African nations

The Lymphatic System Lymphoma Tonsillitis Splenomegaly Lymphoma is a type of cancer involving cells of the immune system, called lymphocytes. While lymphomas are often confined to lymph nodes and other lymphatic tissue, they can spread to other types of tissue almost anywhere in the body Tonsillitis Tonsillitis is an infection or inflammation of the tonsils Most often, tonsillitis is caused by a virus. Less often, it is caused by the same bacteria that cause strep throat. In rare cases, a fungus or a parasite can cause it Splenomegaly Splenomegaly is an enlargement of the spleen beyond its normal size.

The Immune System

The Immune System What is the function of the immune system? It protects body from pathological bacteria, foreign tissue cells and cancerous cells The skin and mucous membranes are mechanical barriers and are examples of the first lines of defense. What are the primary cells of the immune system? Phagocytes Once in the tissues, monocytes develop into phagocytic cells called macrophages. A Kupffer cell is a type of macrophage Phagocytes are cells that are capable of ingesting foreign substances and organisms for their destruction Lymphocytes( B Cells and T Cells are the two major types of lymphocytes) Lymphocytes are the most numerous cells of the immune system Neutrophils Monocytes

The Immune System Antibody: protein compounds that are normally present in the body. They are proteins produced by plasma cells. In general, antibodies produce humoral/antibody-mediated immunity by changing the antigens so that they cannot harm the body. Antibodies are a form of immunoglobulin. Immunoglobulins are proteins. Antibodies combine with specific antigens Antigen: a foreign substance; cause the formation of antibodies when introduced into the body. They are compounds whose molecules have small regions on their surfaces that are uniquely shaped to fit into the combining sites of a specific antibody. Agglutination: process by which antibodies cause antigens to clump or stick together

The Immune System Nonspecific Immunity Tears, mucus, mechanical barriers and the inflammatory response are examples of nonspecific defense mechanisms. Nonspecific immunity confers general protection rather than protection for certain kinds of invading cells or chemicals Relies heavily on phagocytosis which is a nonspecific defense involving ingestion and destruction of microorganisms or other small particles Nonspecific immunity is also called innate immunity because it does not require prior exposure to an antigen Examples are: skin, tears, mucus, inflammation

Inflammation Characterized by Heat Pain Swelling Erythema On a positive note, inflammation brings increased blood flow, which carries an increased number of phagocytic cells, to the injured site.

The Immune System Specific Immunity The immune system’s third line of defense against invading organisms, and includes the activation of B and T cells Called adaptive immunity Is controlled by two classes of lymphocytes called T cells and B cells Has ability to recognize, respond to, and remember harmful substances Examples: natural immunity and artificial immunity

Active Immunity Active Immunity – injection of the causative agent, such as vaccination against measles Vaccination confers active artificially acquired immunity. Injection of the polio vaccine, for example, provides artificial active immunity Active natural immunity occurs after a person has had a disease. When an individual is exposed to a microorganism (for example, the mumps virus) and then develops resistance to future exposures, this is natural active immunity.

Passive Immunity Passive Immunity – injection of protective material that was developed by another individual’s immune system; provides temporary protection; Natural passive immunity occurs when a mom passes her antibodies to the infant through milk Injection of protective antibodies (for example, Hep B antibodies for protetion against Hep B from a needlestick) confers artificial passive immunity

Stem Cells Stem cells arise from primitive cells in the bone marrow. They go through stages of cell development before full development occurs. All lymphocytes that circulate in the tissues arise from primitive cells in the bone marrow called stem cells.

The Immune System Describe the development of B cells. Define: Plasma cells Memory cells

The Immune System Development of B cells Immature B cells are small lymphocytes with antibody molecules in the cytoplasmic membranes These migrate to the lymph nodes, liver and spleen they bind the antigen to the antibody on the surface of immature B cells Immature B cells develop into activated B cells; The activated B cells divide into memory cells and plasma cells. The proper sequence of B cell development is: Stem cells  B cells  plasma cells  antibodies

The Immune System Plasma Cells Memory cells Activated B cells develop into these plasma cells Secrete antibodies into the blood to inactivate antigens Memory cells Recall initial encounters with antigens and increase the immune response Can secrete antibodies but do not immediately do so Remain in reserve in the lymph nodes until they are contacted by the same antigen that led to their formation Develop into plasma cells during repeated exposure to specific pathogens when called upon to fight invasions

The Immune System B cell mechanisms are classified as antibody-related or humoral immunity. Humoral immunity is resistance to disease organisms produced by the actions of antibodies binding to specific antigens while circulating in body fluids.

The Immune System Describe the development of T cells. Define: Sensitized T cells.

The Immune System T-cells (thymus-derived lymphocytes) are the primary cells of cell-mediated immunity and directly attack the invading antigen Development of T cells Stems cells develop in thymus gland shortly before and after birth i.e. T cell maturation begins in the thymus They develop into T cells Sensitized T cells Occurs when an antigen binds to T cell’s surface proteins Interferon is produced by T cells within hours after they have been infected by a virus Interferon works most successfully to inhibit the spread of viruses

The Immune System Humoral Immunity – immunity is mediated by antibodies which change the antigen so that they cannot harm the body Cell-Mediated Immunity – resistance to disease organisms that results from the actions of cells (sensitized T cells) When bound to antigens on invading cell’s surface they release a substance that acts as a poison against the bound cell

What happens when you have an infection? You would expect the number of white blood cells to increase. WHY?

The Immune System Hypersensitivity Allergy The immune system normally protects the body from harmful agents such as bacteria and toxins. Its overreaction to a harmless substance (an allergen) is called a hypersensitivity, or allergic, reaction Anaphylactic shock is a life-threatening hypersensitivity reaction of the immunce system Allergy Allergies are an  abnormal response of the immune system

The Immune System How are allergies tested?

The Immune System Skin testing Blood test An allergy skin test is used to identify the substances that are causing your allergy symptoms. It is often performed by applying an extract of an allergen to your skin, scratching or pricking the skin to allow exposure, and then evaluating the skin's reaction. It may also be done by injecting the allergen under the skin, or by applying it to a patch that is worn on the skin for a specified period of time. Blood test If you dislike needles (and who doesn’t?), there’s a new simple blood test for allergies. It cuts out the pain of traditional skin stick tests and can eliminate the guesswork

The Immune System Immune Diseases: Severe Combined Immune Deficiency (SCID) Acquired Immune Deficiency (AIDS)

The Immune System Severe Combined Immune Deficiency (SCID) Aka Bubble Boy Syndrome Severe Combined Immunodeficiency (SCID) is a group of rare congenital syndromes characterized by little if any immune responses. People with Severe Combined Immunodeficiency are unusually susceptible to recurrent infections with bacteria, viruses, fungi, and other infectious agents that can be life-threatening.

The Immune System Acquired Immune Deficiency (AIDS) AIDS is a condition that develops when a person's body has been weakened by HIV (the human immunodeficiency virus). HIV is found in blood and sexual fluids and spreads mainly through unprotected sexual contact and the sharing of IV drug needles and equipment. When a person becomes infected with HIV, it damages the immune system. A "deficient" immune system is unable to protect a person -- a problem called immunodeficiency. The immune system can no longer fight off the many germs and pathogens that a person normally comes in contact with, so a person infected with HIV becomes ill from diseases that don't usually affect someone without HIV. How is HIV/AIDS transmitted? Through sexual relations Contaminated blood Contaminated needles

QUESTIONS?? Ask ME or your classmates!

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