BIO 241 1st Edition Lecture 11 Outline of Last Lecture I. Systemic vascular resistanceII. Routing of blood flowIII. Mechanisms of venous returnIV. Regulation of blood pressure and flowV. Neural controlVI. Hormonal control of blood pressureVII. Local control (autoregulation)Outline of Current Lecture II. Essential functionsIII. Formation and flow of lymphIV. Lymphatic trunksV. Lymphatic ductsVI. Lymphoid tissueVII. Lymph nodesVIII. Lymph node distributionCurrent LectureII. The lymphatic system drains interstitial fluid back to blood, protects against pathogens, and absorbs and transports dietary lipids. The lymphatic vessels are differentfrom the blood vessels in that they do not form a capillary bed where the vessels run together. It has a closed circulatory system. They are located everywhere except the blood, brain, and spleen. III. As noted before, Starling’s Law of the Capillaries is that 85% of blood is reabsorbed and the other 15% goes to the lymphatic system. Lymph is composed of interstitial fluid and escaped plasma proteins. The escaped and newly created amount of plasma proteins has a net equilibrium of 0. The flow of lymph has no official pump, but it has one-way valves that open/close because of pressure gradients, it has skeletal muscle pumps which is contraction andrelaxation, and it has respiratory pumps where the diaphragm aids in breathing. IV. Lymphatic trunks are similar to the cardiovascular trunks in that they are the larger vessels. The lumbar trunk is the pelvis and lower extremities. The intestinal trunk goes around organs. The bronchomediastinal trunk goes to the middle of your body. The subclavian trunk is the upper extremities. The jugular trunk goes to the head and neck.V. Lymphatic ducts are separated into right and left halves. The left lymphatic duct has the cisterna chyli which holds lymph and other important things. They are drainage fields. It consistsof the left jugular, left subclavian, and left brachiocephalic. The same goes for the right lymphatic duct. The uptake and secretion has a net equilibrium of 0.VI. Lymphoid tissues consist of lymphocytes and macrophages. It occurs in the body in the four ways: diffuse lymphatic tissue (MALT - mucous associated lymphoid tissue), lymphatic nodules (everywhere), primary lymphatic organs (bone marrow and thymus), and secondary lymphatic tissues (lymph nodes, spleen, tonsil). VII. Lymph nodes consist of a collagen capsule, trabeculae, stroma, parenchyma (lymphocytes and macrophages). Within these nodes, the blood travels in through the afferent lymphatics, enters the subcapsular sinus and heads toward hilus where it percolates through the node, and exits through the efferent lymphatics. VIII. The drainage of head and neck where it travels to the superficial cervical lymph nodes → deep cervical lymph nodes → right or left jugular lymph trunks → ducts → blood. The drainage of the upper extremity and thoracic wall, including breasts, travels to cubital lymph nodes → axillary lymph nodes → right or left subclavian lymph trunks → ducts → blood. The drainage of lower extremity and lumbar region which travels to popliteal lymph nodes → inguinal lymph nodes → right or left lumbar lymph trunks → thoracic duct → blood. The drainage of viscera which travels to thousands of lymph nodes located where blood supply enters organ → right or left bronchomediastinal or lumbar lymph trunks → ducts →
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