Chapter 16 - Chapter 16 1) Functions A. Prevents Edema an...

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Chapter 16 1) Functions A. Prevents Edema – an accumulation of fluid within the interstitial (tissue) space leading to an increase in hydrostatic pressure B. Defense against infection (immunity) via 2 mechanisms: 1. filtering of particles from the lymph 2. supporting lymphocyte activity 2) Formation of tissue fluid and lymph A. Fluid that contains water and dissolved substances (including some small protein molecules) leaves the bloodstream in the capillary bed via diffusion and filtration B. Proteins cause the osmotic pressure in the interstitial space to increase, resulting in flow from the bloodstream to the interstitial space C. Results in an increase in hydrostatic pressure in the interstitial space 1. water always moves to an area of greater osmotic pressure D. Increasing interstitial (hydrostatic) pressure forces fluid into the lymphatic capillaries 3) Typical Lymphatic Pathway A. Lymphatic capillaries – microscopic, closed-ended tubes 1. extend into interstitial spaces 2. parallel to networks of blood capillaries 3. similar to blood capillaries B. Lymphatic vessels 1. walls similar to veins, thinner a. 3 layers: i. endothelial lining ii. iii. outer layer of connective tissue 2. have semilunar valves C. Lymph nodes – mass of lymphoid tissue located along the course of a lymphatic vessel D. Lymphatic trunks – drain lymph from lymphatic vessels 1. named for regions they serve E. Collecting ducts – ducts into which lymphatic trunks drain 1. only 2 a. Thoracic duct i. ii. originated in the abdomen iii. empties into the left subclavian vein near the junction of the left jugular vein b. Right lymphatic duct i. originated in the right thorax at the union of the right jugular, right subclavian and right bronchomediastinal trunks ii. empties into the right subclavian vein near the junction of the right jugular vein iii. only empties right upper limb right thorax
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Chapter 16 4) Factors promoting lymph flow through the lymphatic system A. Contraction of skeletal muscles (skeletal pump) B. Pressure changed due to action of breathing muscles (respiratory pump) C. Contraction of smooth muscle in walls of the larger lymphatic vessels D. Valves preventing backflow 5) Obstruction of Lymphatic Flow A. Condition termed Edema – accumulation of fluid in the interstitial space B. Causes – may be caused by any condition that interferes with lymph movement 1. surgical removal of portions of the lymphatic system 2. blockage by parasites 6) Structure of Lymph Node A. Two major regions 1. Cortex – superficial region that is located deep to the capsule and consists of compartments containing germinal centers and sinuses a. Nodules (Germinal Centers) – dense masses of lymphocytes and macrophages in the compartments of a lymph node that constitute the functional units of the node i. Lymphocytes act against foreign particles, such as bacterial cells and viruses that are carried
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Chapter 16 - Chapter 16 1) Functions A. Prevents Edema an...

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