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function of lymphatic system
- production, maintainance and distribution of lymphocytes
- retruen fluid and solutes leaked from blood in peripheral bakc to bloodstream
- distribute hormones, nutrients and waste products into general circulation
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what is the lymph propelled by?
- milking action of skeletal muscle
- pressure changes in thorax during breathing
- valves to prevent backflow
- pulsations of nearby arteries
- contractions of smooth muscles in walls of lymphatics
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what does the right lymphatic duct drain?
right upper arm and right side of head and thorax
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what does thoracic duct arises as?
cisterna chyli which drains the rest of the body
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where does the duct empty lymph into?
venous circulation at junction of internal jugular and subclvian veins on its own side of the body
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where is the T cells in transit in the lymph node?
deep cortex
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where in the lymph node is the follicles and germinal centers?
outer cortex
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what is the role of trabecula in the lymph node?
extend inwards and divide it into compartments
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what does the medullary cords contain?
B cells, T cells, and plasma cells
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what does the lymph sinus contain?
macrophages attached to reticular framework
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what does the cortex of the thymus contain?
young T cells from bone marrow and thymosins
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what does the medulla contain in the thymus?
regulates T cell development
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what does the spleen consist of?
- white pulp around central arteries: mostly lymphocytes on reticular fibers; involvedin immune functions
- red pulp in venous sinuses and splenic cords: rich in RBC and macrophages for pathogens and worn out RBC
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what are the spleen functions?
- site of lymphocyte proliferation and immune surveillance and response
- cleanses blood fo aged cells and platelets, macrophages remove debris
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what are nodules?
- tightly packed lymphoid cells and retivular fibers; each nodule has a germinal center of proliferating B cells
- protect epithelia in body systems open to external environment
- MALT (mucous membranes t/o body)
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what is venous sinuses?
flattened veins with extremely thin walls?
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how is bp regulated in the short term?
increased blood pressure or changes in blood composition stimulate receptors which sends signals to the cardiovascular center in medulla
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how does kidneys regulate arterial blood pressure?
- direct renal mechanism (independent of hormones) increase or descrese urine, decreased or increased blood volume causes kidney to conserve water and BP rises
- indirect mechanism (angiotensin-aldosterone pathway)
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indirect long term mechanism
decrease in arterial blood pressure releases renin, converts angiotensinogen form liver to angiotensin I to angiotensin II by ACE. Angiotensin II acts in four ways to stablize arterial blood pressure and extracellular fluid volume
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what is ADH?
- stimulated by Angiotensin II, secreted by posterior pituitarty
- ADH enhances water reabsorption by kidneys and stimulates vasoconstriction
- also released following decrease in blood volume or increased osmolarty
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what is aldosterone
enhances renal absorption of sodium
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functions of angiotensinII
- secrete aldosterone
- secretes ADH
- triggers thirst
- increases BP by arteriolar constriction
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