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The Urinary System. Function. Remove nitrogenous wastes Maintain electrolyte, acid-base, and fluid balance of blood Homeostatic organ Acts as blood filter Release hormones: calcitriol & erythropoietin. Kidneys as Filters. Diuretic- loose water; coffee, alcohol
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Function • Remove nitrogenous wastes • Maintain electrolyte, acid-base, and fluid balance of blood • Homeostatic organ • Acts as blood filter • Release hormones: calcitriol & erythropoietin
Kidneys as Filters • Diuretic- loose water; coffee, alcohol • Antidiuretic- retain water; ADH • Aldosterone- sodium & water reabsorption, and K+ excretion • GFR= 180 liters (50 gal) of blood/day • 178-179 liters are reabsorbed back into blood • Excrete a protein free filtrate
The Urinary System Maintaining Chemical Homeostasis
blood filtration tubular reabsorption and secretion General Functioning of the Kidney “refreshed” blood urine
Nitrogenous Wastes urea uric acid ammonia
kidneys ureters urinary bladder urethra Organs of the Urinary System
renal pyramids renal pelvis renal cortex renal capsule ureter renal medulla Kidney Anatomy
nephron renal artery renal vein Kidney Anatomy
blood filtration tubular reabsorption and secretion Nephron Functioning “refreshed” blood urine
glomerulus efferent arteriole Bowman’s capsule afferent arteriole proximal convoluted tubule artery distal convoluted tubule peritubular capillaries vein collecting duct loop of Henle
Each kidney contains over 1 million nephrons and thousands of collecting ducts renal cortex renal medulla DCT Glomerulus PCT Collecting duct Loop of Henle
efferent arteriole afferent arteriole Bowman’s capsule glomerulus Glomerular Filtration Filters blood; proteins can’t pass through
Composition of Glomerular Filtrate • Water • Small Soluble Organic Molecules • Mineral Ions
Proximal Convoluted Tubule Reabsorbs: water, glucose, amino acids, and sodium. • 65% of Na+ is reabsorbed • 65% of H2O is reabsorbed • 90% of filtered bicarbonate (HCO3-) • 50% of Cl- and K+
Loop of Henle Creates a gradient of increasing sodium ion concentration towards the end of the loop within the interstitial fluid of the renal pyramid. • 25% Na+ is reabsorbed in the loop • 15% water is reabsorbed in the loop • 40% K is reabsorbed in the loop
Distal Convoluted Tubule Under the influence of the hormone aldosterone, reabsorbs sodium and secretes potassium. Also regulates pH by secreting hydrogen ion when pH of the plasma is low. • only 10% of the filtered NaCl and 20% of water remains
Collecting Duct Allows for the osmotic reabsorption of water. ADH (antidiuretic hormone)- makes collecting ducts more permeable to water-- produce concentrated urine
Urine • Water- 95% • Nitrogenous waste: • urea • uric acid • creatinine • Ions: • sodium • potassium • sulfate • phosphate From the original 1800 g NaCl, only 10 g appears in the urine
heart receptors hypothalamus Hormonal Control of Kidney Function high plasma solute concentration low blood volume
posterior pituitary antidiuretic hormone collecting ducts Hormonal Control of Kidney Function hypothalamus
INQUIRY • List several functions of the kidneys. • What does the glomerulus do? • What are several constitutes you should not find in urine? • What is specific gravity? • What two hormones effect fluid volume and sodium concentration in the urine? • Where are the pyramids located in the kidney? • What vessel directs blood into the glomerulus? • Where does most selective reabsorption occur in the nephron?