Urinary System

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Anatomy and Cell Biology
ACB 221
Keith Russell

Urinary System The digestive tract absorbs nutrients from food and the liver adjusts the nutrient concentration of the circulating blood The cardiovascular system delivers these nutrients along with oxygen from the respiratory system to peripheral tissues As blood leaves these tissues it carries the CO and other waste 2products generated by active cells to the sites of excretion The COis eliminated at the lungs Most of the 2 organic waste products along with excess water and electrolytes are removed and excreted by the urinary system Primary functions of the urinary system o Regulating plasma concentrations of sodium potassium chloride calcium and other ions by controlling the quantities lost in the urine o Regulating blood volume and blood pressure by a adjusting the volume of water lost in the urine by adjusting the amount of sodium retained by the body or lost in the tubules b releasing erythropoietin hormone that produces new RBCs and c releasing reninIn times of O deficit the kidneys will secrete erythropoietin to produce more RBCs which 2will increase the efficacy of O transport to cells in need 2 Low blood pressure stimulates renin secretionrenin will convert into angiotensin II which is a potent vasoconstrictor Renin is an enzymatic hormone that triggers a chain reaction which is important in salt conservation as well as arterial pressure and volume control Renin will also cause the release of aldosterone which will increase the uptake of sodium o Contributing to the stabilization of blood pH o Conserving valuable nutrients by preventing their excretion in the urine o Eliminating organic waste products especially nitrogenous wastes such as urea and uric acid toxic substances and drugs o Synthesizing calcitriol a hormone derivative of vitamin D that stimulates calcium ion absorption by 3the intestinal epithelium o Assisting the liver in detoxifying poisons and during starvation deaminating amino acids so that other tissues can break them down Kidneys o The renal cortex is the outer layer of the kidney while the renal medulla is the inner layer of the kidney The renal medulla consists of 618 distinct conical or triangular structures called renal pyramids The base of each pyramid faces the cortex and the tip or renal papilla projects into the renal sinus Each pyramid has a series of fine grooves that converge at the papilla Adjacent renal pyramids are separated by bands of cortical tissue called renal columns o The renal lobe contains a renal pyramid the overlying area of renal cortex and adjacent tissues of the renal columns Urine production occurs in the renal lobes Ducts within each renal papilla discharge urine into a cupshaped drain called the minor calyx For or five minor calyces merge to form a major calyx and the major calyces combine to form a large funnel shaped chamberthe renal pelvis The renal pelvis is connected to the ureter at the hilum of each kidney Urinary SystemRenal Lobe o Urine production begins inmicroscopic tubular structurescalled nephrons in the cortex of each renal lobe Renal o Nephrons are considered the basic cortex functional unit of the kidneyso There are 2 main components in thenephronVascular component For nourishing the kidneyTaking part in thebloodfiltration process within Renal Renal pyramidmedulla the glomerulusTubular component Begins at the renalcorpuscle glomerulus an Bowmans capsule
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