The Urinary System Chapter 26(24) Urinary System Functions: Removing nitrogenous waste products Urea and uric acid Fluid and electrolyte balance Blood volume and blood pressure Regulating levels of sodium, potassium and chloride Acid – base balance Loss and conservation of H + and bicarbonate ions Urinary system includes: The kidneys - Produce urine The ureters The urinary bladder - Stores urine The urethra The kidneys Location and Support of kidneys Left kidney extends slightly more superiorly than right Both kidneys and adrenal glands are retroperitoneal Hilum o Entry for renal artery and renal nerves o Exit for renal veins and ureter Coronal Sectional anatomy of the kidneys Two regions: o Cortex – outer layer The cortex is composed of roughly 1.25 million nephrons Very vascular o Medulla - inner The medulla consists of 6-18 renal pyramids Renal papilla extends to calyx Renal columns – between pyramids Major and minor calyces along with the pelvis drain urine to the ureters Blood supply and innervation of the kidneys Renal arteries branch repeated o Renal artery o Segmental artery o Interlobar artery o Arcuate artery = arc o Interlobular artery o Afferent arterioles o NEPHRON Renal venous flow follow opposite pattern ending with renal veins Nephron Functional unit of the kidney BIO 1222 Ch 26 Page 1
Consists of o Blood vessels Afferent arteriole Glomerulus Efferent arteriole Peritubular capillary bed o Renal tubule Glomerular (Bowman’s) capsule Proximal convoluted tubule Nephron Loop (of Henle) Distal convoluted tubule Location of nephron blood vessels o Arcuate artery separates the cortex from the medulla o Branches à interlobular arteries à afferent arterioles à glomerulus à efferent arterioles o Glomerulus – ball of capillaries (part of the nephron) o Glomerulus only capillary bed in the body that is both fed and drained by arterioles Blood flow in Nephron Afferent arteriole Glomerulus Efferent arteriole Peritubular capillaries o Reabsorption (from tubule into blood) o Secretion (from blood into tubule) Renal venule Renal veins The renal corpuscle and renal tubule; parts of the Nephron The renal corpuscle is composed of o Glomerular(Bowman’s) capsule and the glomerulus The renal tubule consists of o Proximal convoluted tubule (PCT) o Loop of Henle o Distal convoluted tubule (DCT) Filtrate is produced at the renal corpuscle Tubes carry filtrate into collecting system à Collecting ducts and papillary ducts Two types of nephrons: Cortical nephrons o ~85% of all nephrons o Located in the cortex Juxtamedullary nephrons o Closer to renal medulla BIO 1222 Ch 26 Page 2
o Loops of Henle extend deep into renal pyramids Nephron functions include: GLOMERULUS: o Production of filtrate (160 L/day) TUBULES: o Reabsorption of organic nutrients o Reabsorption of water and ions o
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- Spring '16