Introduction by Period 6, 2014

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Vessels andFluid

• Vessels- A network of lymphatic vessels, often called lymphatics, begins in peripheral tissues and ends at connections to the venous system.

• Fluid- A fluid called lymph flows through the lymphatic vessels. Lymph resembles plasma but contains a much lower concentration of suspended proteins.

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The Lymphs

• Lymphocytes- Specialized cells that preform an array of specific functions in defending the body.

• Lymphoid Tissue and Organs- Tissues are collections of loose connective tissue and lymphocytes. Organs are more complex structures that contain large number of lymphocytes and are connected to lymphatic vessels.

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Functions: Part 1

• The production, maintenance, and distribution of lymphocytes

• The return of fluid and solids from peripheral tissues to blood

• The distribution of hormones, nutrients, and waste products from their tissues of origin to general circulation

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Functions: Part 2

• Lymphocytes are produced and stored within lymphoid organs, such as spleen, thymus, and bone marrow.

• Lymphocytes mount a defense against invading bacteria with a immune response.

• Immunity is the body’s ability to resist infection and disease.

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Lymphatic Capillaries

• Smallest lymphatic vessel• They don’t have basement

membranes, so viruses, fluid, and bacteria can flow in to the lymph. capillaries

• From lymph capillaries, lymph flows into larger vessels, then to the trunk of the body.

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Lymphatic Ducts

Two main Lymphatic Ducts Thoracic Duct- collects lymph

from the lower abdomen. Right Lymphatic Duct-

Delivers lymph from the right side of the body above the diaphragm and empties into right subclavian vein.

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What are lymphocytes?• Lymphocytes are specialized cells that perform specific functions in defending the body

• They account for roughly 25% of the circulating white blood cell population

• The blood contains three classes of lymphocytes: T cells, B cells, and NK cells

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T Cells (thymus-dependant cells)- they attack foreign cells and body cells infected by viruses. 80% of circulating

B Cells (Bone Marrow Derived Cells)- They produce and secrete antibodies and these bind specific chemical targets called antigens, which are usually pathogens. 10-15% of circulating lymphocytes

NK Cells (Natural Killer Cells)- these lymphocytes attack foreign cells, normal cells with viruses, and cancer cells in tissues. 5-10% of circulating lymphocytes

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• Lymphoid nodules are masses of lymphoid tissue that are not surrounded by a fibrous capsule.

• Their size can increase or decrease, depending on the number of lymphocytes present at any given moment.

• Lymphoid nodules are located beneath the epithelia lining various organs of the respiratory , digestive, and urinary systems.

• We have lymphoid nodules because our food usually contain foreign proteins that often contain bacteria. Therefore, our lymphoid nodules play apart in our digestive tract as an important role as the defense in our body.

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Common Lymphoid Nodules

• The tonsils, large lymphoid nodule in the walls of the pharynx, guard the entrance to the digestive and respiratory tracts.

• Fused lymphoid nodules dominate the walls of the appendix, a blind pouch located near the junction of the small in large intestine.

o When the nodules become inflamed, an infection develops such as tonsillitis or appendicitis

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Lymph OrgansLymph Nodes- small, oval shaped organs covered by a fibrous capsule. They filter lymph fluid before it reach the veins. Located in regions where they can find and get rid of pathogens. Thymus- pink gland, site of where T cells are made. Gradually decreases in size with age. Divided into two parts called lobules and septae. Each one contains a central medulla. Secrete hormones called thymosins.

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• The Spleen- filters blood and removes abnormal blood cells. Tells B cells and T cells to circulate through blood. Located between the stomach and the left kidney. Divided into areas of white pulp and red pulp.

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Autoimmune Disorders-develop when the immune response mistakenly targets normal body cells and tissues. -autoantibodies target self-antigens that are usually ignored-examples include Rheumatoid Arthritis and Insulin-Dependent Diabetes Mellitus

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Immunodeficiency Diseases-either the immune system fails to develop normally or the immune response is blocked in some way-severe combined immunodeficiency disease: fail to develop either cellular or antibody-mediated immunity-Because the immune response doesn’t work correctly, any mild infections can be fatal.-Examples= AIDS, HIV, etc…

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Allergies• Type I-Immediate

hypersensitivity reactions- is a rapid and epically severe response to the presence of an antigen

• The severity of this reaction depends on the persons location and severity

• Type II-cytotoxic hypersensitivity- 

• the antibodies produced by the  immune response bind to antigens on the patient's own cell surfaces.

• The cross reactions that occur following the transfusion of an incompatible blood type

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Allergies

• Type III-immune complex disorders

• Result if phagocytes are not able to rapidly remove circulating antigen-antibody complexes.

• The presence of these complexes leads to inflammation and tissue damage.

• Type IV- delayed hypersensitivity

• Inflammatory response that occurs two to three days after exposure to an antigen (i.e. poison ivy or poison oak)

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