Chapter 12: The Lymphatic System

1. Chapter 12: The Lymphatic System Max Bremmerkamp (Calvin says hi)

2. Anatomy and Physiology • Lymphatic Vessels- elaborate drainage system that picks up excess tissue fluid • Lymph Nodes- remove foreign materials like bacteria and cancer cells from the lymphatic system • Spleen- filters blood • Thymus- (functions at peak levels during youth) produces hormones • Tonsils- trap and remove and bacteria or other foreign pathogens entering the throat • Peyer’s Patches- capture and destroy bacteria to prevent from entering the intestinal wall

4. Part I: the Lymphatic System

5. Overview: Lymphatic System • The lymphatic system is divided into two parts: • Network of lymphatic vessels • Transport fluids back to the blood, that have escaped from the vascular system • Lymphoid tissues and organs • House phagocytic cells and lymphocytes, which play essential roles in body defense and resistance to disease

6. Overview: Lymphatic Vessels • During the exchange of nutrients wastes and gases, fluid is expelled out of the blood. The fluid must return to the blood system to maintain blood volume, if it does not the fluid accumulates, producing edema. This fluid (now known as lymph or “clear water”) is picked up by very permeable lymphatic vessels (lymphatics), and is carried toward the heart.

8. Overview: Vessels and Nodes • Proteins, debris, bacteria, and viruses may enter the lymphatic system easily. Harmful cells may use the lymphatic system to travel throughout the body, but may be resolved when the lymph travels through lymph nodes to become cleaned. • Lymph is transported from the capillaries to collecting vessels and is returned to the venous system through either the right lymphatic duct or the thoracic duct. Which empties lymph into the subclavian vein on either side of the body.

9. Internal jugular vein Entrance of right lymphatic duct into right subclavian vein Thoracic duct entry into left subclavian Vein Thoracic Duct Cisterna chyli (receives lymph drainage from digestive organs

10. Part II: Body Defenses

11. Overview: Body Defenses • The body is constantly being attacked by bacteria, viruses, and fungi swarms • The body’s immune system is comprised of two systems • Innate defense system (nonspecific defense system)- responds immediately to protect the body from any foreign materials • Adaptive defense system (specific defense system)- attack particular foreign substances

12. Overview: Innate Body Defenses • Some innate resistance to disease is inherited • EX: some humans never get some forms of tuberculosis, and more commonly barriers that cover the body’s surface which protect against harmful microorganisms known as pathogens • The body’s first line of defense is the skin and mucous membranes. As long as the skin is not damaged it is resilient to most microorganisms • After the skin the body uses large amounts of cells and chemicals • Natural Killer (NK) cells- roams the body, and kills cancer and virus-infected body cells • Inflammatory response- release of chemicals to alert the body and kill any pathogens

13. The four most common identifiers for inflammation

14. Overview: Phagocytes • If a pathogen makes it through the mechanical barrier it is confronted with a phagocyte (such as: a macrophage or a neutrophil), where it will be surrounded and enclosed in a vacuole and is then broken down by Lysosomes

15. Overview: Adaptive Body Defenses • The immune system’s response to a threat involves an increase internal nonspecific defense and provides protection to the body • Two arms of adaptive defense system • Humoral immunity (antibody-mediated immunity)- provided by antibodies present in the body’s humors • Cellular immunity (cell-mediated immunity)- lymphocytes defend the body

16. Overview: Antigens • Antigen- any substance capable of mobilizing our immune system • Self-antigen- do not trigger an immune response in us, they are strongly antigenic to other people • Hapten- (incomplete antigen)- small molecules that can link together to form a protein that is recognized as an antigen which causes the body to attack itself

17. Overview: Cells of the Adaptive Defense System • Lymphocytes • Types: • B Lymphocytes (B Cells)- produce antibodies • T Lymphocytes (T Cells)- cell mediated arm of the adaptive defense system • Originate from hemocytoblasts. When it leaves the marrow the lymphocytes are identical and later become B and T cells based off of where in the body it becomes immunocompetent • Lymphocytes that bind strongly with self-antigens are destroyed creating a process called self-tolerance • Antigen-presenting cells(APCs)- assist lymphocytes that respond to antigens • Engulf antigens and then present fragments of them on their own surfaces where they can be recognized by T cells

18. Overview: Antibody Structure, Class, and Function • Structure • All consist of four amino acid chains linked together by disulfide bonds • Usually T- or Y-shaped • Antibodies have differing V regions depending on the antigen it attacks • The C region stays constant for all antibodies • Class • IgM, IgA, IgD, IgG, and IgE • Function • Neutralization- occurs when antibodies bind to specific sites on bacteria or virus • Agglutination- clumping of foreign cells • Precipitation- cross-linking reaction

20. Overview: Organ Transplant and Rejection • Four major types of graphs: • Autografts- transplant of tissue from one site to another in the same person (Ideal) • Isografts- tissue graphs donated by a genetically identical person (Ideal) • Allografts- tissue graphs take from a person other than a twin • Xenografts- tissue grafts harvested from a different animal species • After surgery to prevent rejection the patient receives immunosuppressive therapy, which includes one or more of the following: • corticosteroids-suppress inflammation • Antiproliferative drugs • Radiation therapy • Immunosuppressor drugs

21. Overview: Immune Disorders • Autoimmune disease- the immune system loses the ability to distinguish between self-antigens and foreign antigens • Common autoimmune diseases • Rheumatoid arthritis (RA)- destroys joints • Myasthenia Gravis- impairs communication between nerves and skeletal muscle • Graves’ disease- thyroid gland produces excessive amounts of thyroxine • Type 1 diabetes mellitus- destroys pancreatic beta cells • Systemic Lupus Erythematosus (SLE)- affects the kidneys, heart, lungs, and skin • Glomerulonephritis- impairs kidney function

22. Overview: Allergy and Immunodeficiency • Allergies (hypersensitivities)- abnormally vigorous immune response in which the immune system causes tissue damage as it fights of “threats” • Immunodeficiency- the production or function of immune cells is abnormal