The Lymphatic System - PDF

Chapter 9 The Lymphatic System Fundamentals of Anatomy and Physiology  The Lymphatic System Drain interstitial fluid from tissue spaces ▪ Prevent edema Transports lymph through lymphatics ▪ Lymphatics: lymph capillaries and vessels Transport digested fat to blood ▪...

Chapter 9 The Lymphatic System Fundamentals of Anatomy and Physiology  The Lymphatic System Drain interstitial fluid from tissue spaces ▪ Prevent edema Transports lymph through lymphatics ▪ Lymphatics: lymph capillaries and vessels Transport digested fat to blood ▪ Lacteals: special lymphatics in small intestine ▪ Chyle: milky lymph in lacteals  The Lymphatic System Develop immunities Destroys harmful microorganisms Produce lymphocytes Controls body fluid Transport fluids back to the blood.  The Functions of the System and the Structure and Functions of the Lymphatic Vessels  The Lymphatic System Two parts ▪ Lymph, Lymphatic vessels, Lymph nodes ▪ Lymphoid tissues and organs – tonsils, spleen, thymus gland and vermiform appendix  Lymphatic Characteristics Interstitial fluid - when the plasma moves out of the capillaries and into the spaces between cells *important to be drained to avoid edema Lymph - once the interstitial fluid enters the lymphatic capillaries. ▪ excess tissue fluid carried by lymphatic vessels..  Lymph Components of Lymph ▪ Water ▪ Plasma solutes (ions, gases, nutrients, proteins) ▪ Blood cells ▪ Hormones ▪ Enzymes ▪ Waste products  Lymph Harmful materials that enter lymph vessels ▪ Bacteria ▪ Viruses ▪ Cancer cells ▪ Cell debris  Lymphatic Characteristics Special lymph capillaries: Lacteals ▪ Collect digested fats and transport them from digestive tract to the blood.  Lymphatic Characteristics Properties of lymphatic vessels ▪ One-way system toward the heart ▪ No pump ▪ Not found in the CNS, red bone marrow, portion of the spleen.. Travel along with blood vessels. lymphatic vessels - tubes that are closed at one end. Lymphatic vessels start with lymphatic capillaries Lymphatic ducts Main collecting funnel Lymphatic trunks Lymphatic collecting vessels - Larger lymph vessels - Resemble veins but Much larger and have thinner walls and more permeable than more valves blood capillaries Lymphatic capillary  Lymphatic Vessels Lymphatic collecting vessels ▪ Collects lymph from lymph capillaries ▪ Carries lymph to and away from lymph nodes  Lymphatic Vessels Lymphatic collecting vessels ▪ Returns fluid to circulatory veins near the heart ▪ Right lymphatic duct ▪ Thoracic duct  Lymphatic Vessels.  Lymph Nodes Filter lymph before it is returned to the blood ▪ Defense cells within lymph nodes ▪ Macrophages – engulf and destroy foreign substances ▪ Lymphocytes – provide immune response to antigens  Lymph Nodes.  Lymph Nodes Found along lengths of lymphatics ▪ Hilum: depression on one side where efferent vessels leave and nodal artery enters ▪ Efferent: exit lymph node at the hilum ▪ Afferent: enter lymph node at various locations ▪ Trabeculae: divide the node into compartments ▪ Germinal centers of compartments produce lymphocytes  Lymph Node Structure.. Lymph Circulation  Lymph Circulation Interstitial fluid: plasma in interstitial spaces Lymph: interstitial fluid in lymph capillaries ▪ Passes into lymphatics Lymphatics join to form lymph trunks  Lymph Circulation Lymph circulation maintained by: ▪ Normal skeletal muscle contractions ▪ Compresses lymph vessels and forces lymph in one direction ▪ Respiratory or breathing movements ▪ Smooth muscle in lymphatic vessels  Lymph Circulation Lymph trunks ▪ Lumbar: drains lower extremities and pelvis ▪ Intestinal: drains abdominal region ▪ Bronchomediastinal and intercostal: drain thorax ▪ Subclavian: drains upper extremities ▪ Jugular: drains head and neck.  Lymph Circulation Individual trunks drain into two main trunks ▪ Thoracic duct: o drains into the left subclavian vein ▪ Right lymphatic duct: o drains into the right subclavian vein The Organs of the Lymphatic System  The Organs of the Lymphatic System Tonsils ▪ Palatine, pharyngeal, tubal, and lingual ▪ Small masses of lymphoid tissue around the pharynx ▪ Protect the nose and oral cavity o Trap and remove bacteria and other foreign materials ▪ Tonsillitis is caused by congestion with bacteria  The Organs of the Lymphatic System.  The Organs of the Lymphatic System Thymus ▪ Located low in the throat, overlying the heart ▪ Functions at peak levels only during childhood ▪ Produces hormones (like thymosin) to program lymphocytes  The Organs of the Lymphatic System Peyer’s patches ▪ Found in walls of small intestine ▪ Resemble tonsils in structure ▪ Capture and destroy bacteria in the intestine (macrophages)  The Organs of the Lymphatic System Spleen ▪ Located on the left side of the abdomen ▪ Largest mass of lymphatic tissue ▪ Phagocytizes worn-out RBCs and platelets o Recycles hemoglobin ▪ Produces lymphocytes and plasma cells ▪ Forms blood cells in the fetus ▪ Stores blood for release during hemorrhage  The Organs of the Lymphatic System Vermiform Appendix ▪ Assists in the maturing of B lymphocytes and produces immunoglobulin A (IgA) antibodies.  Body Defenses The body is constantly in contact with bacteria, fungi, and viruses (pathogens) The body has two defense systems for foreign materials: ▪ Nonspecific defense system o Mechanisms protect against a variety of invaders o Responds immediately to protect body from foreign materials ▪ Specific defense system o Specific defense is required for each type of invader o Also known as the immune system. Immunity  Specific Defense: The Immune System – Third Line of Defense Antigen specific – recognizes and acts against particular foreign substances Systemic – not restricted to the initial infection site Has memory – recognizes and mounts a stronger attack on previously encountered pathogens  Immunity Ability of body to resist: ▪ Infection from pathogens ▪ Damage from foreign substances and harmful chemicals Humoral immunity ▪ B lymphocytes: produce antibodies o Fight circulating bacteria and viral infections o Become plasma cells when they enter tissues  Immunity Cellular immunity (Cell-mediated) ▪ T lymphocytes o Come from thymus glands o Fight intracellular viruses, fungi, parasites, cancer Antigens and Antibodies  Antigens (non-self) Any substance capable of exciting the immune system and provoking an immune response Examples of common antigens: ▪ Foreign proteins ▪ Nucleic acids ▪ Large carbohydrates ▪ Some lipids ▪ Pollen grains ▪ Microorganisms  Self-Antigens Human cells have many surface proteins Our immune cells do not attack our own proteins Our cells in another person’s body can trigger an immune response because they are foreign ▪ Restricts donors for transplants  Antibodies and Antigens Antibody – Y-shaped immunoglobins created to bind to various antigen-biding sites. Antigen – any molecule that triggers an immune response. Generally large and complex, making it distinguishable from self. Cells of the Immune Response and Other Defenses  Cells of the Immune Response and Other Defenses B cells (B lymphocytes) ▪ produce antibodies (immunoglobulins) ▪ develop in the bone marrow from stem cells. ▪ Plasma cells: replicated B cells Helper T cells ▪ stimulate production of: o Killer T cells o More B cells  Cells of the Immune Response and Other Defenses Killer T cells: ▪ attack virus-invaded body cells ▪ attack cancer cells ▪ reject body grafts Memory cells ▪ descendants of activated T and B cells Suppressor T cells ▪ slow down activities of B and T cells  Cells of the Immune Response and Other Defenses Macrophages ▪ engulf and digest antigen ▪ present them to T cell for recognition  Cells of the Immune Response and Other Defenses Lymphokines: chemicals released by sensitized T cells Monokines: chemicals released by activated macrophages Skin: mechanical barrier ▪ acid mantle, sebum Lysozyme: (tears and saliva) attacks bacteria Mucous membranes: trap microorganisms and debris Hydrochloric acid: (stomach) destroys microorganisms  Humoral (Antibody-Mediated) Immune Response.  Cellular (Cell-Mediated) Immune Response.  Allergies Allergies occur when your immune system overreacts to substances called allergens. Pollen Dust mites Mold spores Pet dander Food Insect stings Medicines Allergies can range from minor to severe. Anaphylaxis is a severe reaction that can be life-threatening..  Kinds of Immunity Innate or Genetic Immunity: ▪ Immunity an organism is born with ▪ Genetically determined ▪ May be due to lack of receptors or other molecules required for infection o Immunity of mice to poliovirus.  Kinds of Immunity Acquired Immunity ▪ Immunity that an organism develops during lifetime. ▪ Not genetically determined ▪ May be acquired naturally or artificially o Development of immunity to measles in response to infection or vaccination.  Types of Acquired Immunity I. Naturally Acquired Immunity: Obtained in the course of daily life. A. Naturally Acquired Active Immunity: Antigens or pathogens enter body naturally. Body generates an immune response to antigens. Immunity may be lifelong (chickenpox or mumps) or temporary (influenza or intestinal infections). B. Naturally Acquired Passive Immunity: Antibodies pass from mother to fetus via placenta or breast feeding (colostrum). No immune response to antigens. Immunity is usually short-lived (weeks to months). Protection until child’s immune system develops.  Types of Acquired Immunity II. Artificially Acquired Immunity: Obtained by receiving a vaccine or immune serum. A. Artificially Acquired Active Immunity: Antigens are introduced in vaccines (immunization). Body generates an immune response to antigens. Immunity can be lifelong (oral polio vaccine) or temporary (tetanus toxoid). B. Artificially Acquired Passive Immunity: Preformed antibodies (antiserum) are introduced into body by injection. Snake antivenom injection from horses or rabbits. Immunity is short lived (half life three weeks).  Types of Acquired Immunity Antibody types (Immunoglobulin) ▪ Soluble proteins secreted by B cells (plasma cells) ▪ Carried in blood plasma ▪ Capable of binding specifically to an antigen o IgG: attacks viruses, bacteria, and toxins; activates complement o IgA: found in exocrine gland secretions o IgM: response to bacteria or food antigens o IgD: found on surface of B lymphocytes o IgE: associated with allergic reactions Disorders of the Lymphatic System  Disorders of the Lymphatic System Lymphedema Lymphedema is where edema, or fluid collection, leads to swelling of limbs and other regions drained by the affected lymphatic channel.  Disorders of the Lymphatic System Lymphadenopathy Lymphadenopathy occurs when the lymph nodes swell due to infections For example, an infection of the leg such as an abscess or cellulitis may lead to swelling of lymph nodes at the groin. These lymph nodes may be painful, red, warm and tender to touch. Viral infections like measles, German measles (rubella), glandular fever, HIV AIDS etc. may also cause lymphadenopathy of all the lymph nodes..  Disorders of the Lymphatic System Lymphoma Lymphoma is cancer of the lymphatic system. This cancer may be of various forms. The lymphomas can begin in the stomach or intestinal lymph nodes as well. Symptoms of lymphoma include fatigue or tiredness, fever, propensity for infections, unexplained weight loss and excessive sweating at night. Other cancers like breast cancer (affects lymph nodes of the arm pit) may also spread to the nearest lymph nodes..  Disorders of the Lymphatic System Lymphangitis An inflammation of the lymphatic vessels with accompanying red streaks visible in the skin..  Disorders of the Lymphatic System AIDS, or Acquired Immune Deficiency Syndrome Caused by infection with the Human Immunodeficiency Virus (HIV). This virus is transmitted by contact with body fluids containing the virus through sexual contact, through contaminated needles, during birth from an infected mother, or by receiving contaminated blood in a transfusion.  Disorders of the Lymphatic System Coronavirus Disease (COVID-19) An infectious disease caused by the Severe acute respiratory syndrome- related coronavirus 2 (SARS-CoV-2) virus. Most people infected with the virus will experience mild to moderate respiratory illness and recover without requiring special treatment. However, some will become seriously ill and require medical attention. Older people and those with underlying medical conditions like cardiovascular disease, diabetes, chronic respiratory disease, or cancer are more likely to develop serious illness. Anyone can get sick with COVID-19 and become seriously ill or die at any age.  Thank You! Do you have any questions for me before we go?