Unit 8 Review

Unit 8 Review: 1. List the major structures involved in the lymphatic system and describe their function(s). ● Lymphoid cells ○ Lymphocytes ■ T-cells: made in thymus, cell-mediated immunity ■ B-cells: made in red bone marrow, antibody-mediated immunity ■ NK cells: made in red bone marrow, non-specific immunity ○ Phagocytes (macrophages) ■ Digests foreign particles, pathogens, and abnormal cells like cancer cells, also activates T-cells ● Lymph ○ The fluid contents of lymphatic vessels ○ Lymph is interstitial fluid that enters lymphatic vessels ● Lymphatic vessels ○ A network of vessels that begin at the peripheral tissues and extend to the veins ○ Close-ended ● Red bone marrow ○ A primary lymphatic organ that creates B-cells and NK cells ○ Hemocytoblasts differentiate into lymphoid stem cells. When presented with interleukin-7 the stem cells differentiate into NK cells and B-cells. If not presented with interleukin-7 then the stem cells migrate to the thymus to create T-cells there ● Thymus ○ Produces thymosin hormone which stimulates development of T-cells ○ It is a primary lymphatic organ so it creates T-cells from stem cells ● Tonsils ○ Used to fight infections in your mouth ○ You have 5 tonsils (1 pharyngeal, 2 palatine, and 2 lingual tonsils) ● Spleen ○ Removes abnormal blood cells and other blood components by phagocytosis ○ Stores iron recycled by blood cells ○ Initiates immune cells in response to antigens circulating in the blood ○ Flow of blood through the spleen gives phagocytes time to recognize and engulf damaged or infected cells in the blood, and trigger and immune response ● MALT ○ Lymphatic nodules associated with mucous membranes ○ Protects the epithelia of the respiratory, digestive, reproductive, and urinary systems ○ Eg. Peyer's patches in small intestine ● Lymph nodes ○ Many found in the body, but primarily in the neck, axillae, and groin ○ Filters and purifies lymph ○ Lymphocytes and lymph node attacks and destroys pathogens ○ Protects entrances and monitors lymph 2. State the purpose of the lymphatic system. ● Production, maintenance and distribution of lymphocytes ● Ensuring stable blood volume and comparable interstitial fluid composition throughout the body ● Assists in transport of hormones, nutrients, and waste products 3. Describe the major pattern of lymphatic drainage and its relationship with blood. ● Lymphatic vessels lie along arteries and veins. Anywhere in the peripheral tissues the interstitial fluid from the blood vessels will move into the lymphatic capillaries and become lymph. In lymphatic vessels there are moving and fixed macrophages that look through the lymph and engulf the bad things in the lymphatic fluid. Lymph vessels are close ended, so the bad cells cannot leave and must get destroyed. The lymphatic fluid moves along the lymphatic vessels toward the heart, where they collect and form lymphatic trunks. These trunks then dump their interstitial fluid into lymphatic ducts (thoracic or right lymphatic ducts depending on where in the body it came from). From the ducts they merge into the subclavian veins and the interstitial fluid is put back into circulation. 4. Discuss the role of immune cells and types of immunity. ● NK cells: nonspecific killer cells, attacks foreign cells, abnormal cells, pathogens or anything typically bad with no specificity ● T-cells: cell-mediated immunity ○ T-cytotoxic cells: attacks foreign cells or body cells infected by viruses ○ Helper T-cells: stimulate the activation of T-cells and B-cells ○ Regulatory T-cells: moderates the activity of other T-cells and B-cells ○ Memory T-cells: respond to previously encountered antigens ● B-cells: antibody-mediated immunity ○ Differentiates into plasma cells to create antibodies against encountered pathogens ○ Naturally acquired active immunity ■ Develops after exposure to antigens in the environment ○ Naturally acquired passive immunity ■ Antibodies are passed from mother to fetus via the placenta and breast milk ○ Artificially acquired active immunity ■ Antibodies are made due to exposure to a vaccine ○ Artificially acquired passive immunity ■ Antibodies are gathered from a human or animal and injected into an individual (ie. antiserum from a snake bite)