Unit 7: Urinary System - Anatomy of the Urinary System Kidneys ● The kidneys are located against the dorsal body wall in a retroperitoneal position

Unit 7: Urinary System - Anatomy of the Urinary System...

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Anatomy of the Urinary System Kidneys The kidneys are located against the dorsal body wall in a retroperitoneal position It we take a closer look inside the kidney you can see that it is divided into a few regions. The outer region of the kidney is called the renal cortex, the inside region of the kidney is the renal medulla and the inner collecting tube is the renal pelvis. Aorta renal artery segmental artery interlobar artery arcuate artery cortical radiate artery afferent arteriole glomerulus (capillaries) efferent arteriole peritubular capillaries cortical radiate vein arcuate vein interlobar vein renal vein inferior vena cava Ureters, Urinary Bladder and Urethra Attached to each kidney is a ureter, which connects the kidneys to the bladder Ureters use peristalsis to move the urine down the tube and into the bladder Smooth muscle in the bladder wall is able to stretch without being triggered to contract - so the bladder fills without the sensation of needing to urinate (until stretch sensors are activated) The internal and external urethral sphincters make sure urine isn't lost. The internal sphincter is relaxed by reflex impulses from the spinal cord while the external sphincter is under voluntary control. Control of the external sphincter is actually what is learned during “potty training” of children Microanatomy of the Kidney Nephrons Each kidney contains approx. one million nephrons, which are the basic structural and functional units of the urinary system. A nephron is a microscopic convoluted blind ended tube that drains through a renal pyramid. They are responsible for forming urine The components of a single nephron include the glomerular or Bowman’s capsule, proximal convoluted tubule (PCT), loop of Henle and distal convoluted tubule (DCT) There are two types of nephrons based on their location in the regions of the kidney: cortical nephrons and juxtamedullary nephrons. Cortical nephrons are located entirely in the cortex and account for the majority of nephrons, approximately 85% Juxtamedullary nephrons are found at the boundary of the cortex and medulla and are responsible for producing concentrated urine Nephron: Bowman’s Capsule → Proximal Convoluted Tubule → Loop of Henle → Distal Convoluted Tubule The first component of the nephron is the Bowman’s capsule, which is the blind end of each nephron - Bowman’s capsule is wrapped around a small capillary bed called the glomerulus (bowman’s capsule is in renal cortex) first step in the formation of urine is the passage of fluid from the glomerulus into
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the cavity of the Bowman’s capsule. The Bowman’s capsule then leads to the first tubule section of the nephron, the proximal convoluted tubule ( PCT ) PCT is also located in renal cortex. The PCT leads to a hairpin-looped section of the nephron called the loop of Henle The loop of Henle consists of both descending and ascending limbs. This is the
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  • Spring '14
  • Kidney anatomy, Nephron, loop of Henle

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