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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
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
what does the right lymphatic duct drain?
right upper arm and right side of head and thorax
what does thoracic duct arises as?
cisterna chyli which drains the rest of the body
where does the duct empty lymph into?
venous circulation at junction of internal jugular and subclvian veins on its own side of the body
where is the T cells in transit in the lymph node?
where in the lymph node is the follicles and germinal centers?
what is the role of trabecula in the lymph node?
extend inwards and divide it into compartments
what does the medullary cords contain?
B cells, T cells, and plasma cells
what does the lymph sinus contain?
macrophages attached to reticular framework
what does the cortex of the thymus contain?
young T cells from bone marrow and thymosins
what does the medulla contain in the thymus?
regulates T cell development
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
what are the spleen functions?
- site of lymphocyte proliferation and immune surveillance and response
- cleanses blood fo aged cells and platelets, macrophages remove debris
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)
what is venous sinuses?
flattened veins with extremely thin walls?
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
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)
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
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
what is aldosterone
enhances renal absorption of sodium
functions of angiotensinII
- secrete aldosterone
- secretes ADH
- triggers thirst
- increases BP by arteriolar constriction