copyright © 2009 pearson education, inc. the urinary system regulates many aspects of homeostasis...
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Copyright © 2009 Pearson Education, Inc.
The urinary system regulates many aspects of homeostasis including the volume, pH, pressure, and composition of the blood
The urinary system eliminates nitrogenous wastes, water, salts and excess ions in the urine
The kidneys are the primary organs of the urinary system
Copyright © 2009 Pearson Education, Inc.
Organs Eliminate Waste
Kidneys are responsible for excreting urine Nitrogen-containing wastes Water Carbon dioxide (as HCO3-)
Inorganic salts and hydrogen ions
Urine travels from the kidneys down the ureters to the urinary bladder, where it is temporarily stored until it is excreted through the urethra
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By Producing Urine, the KidneysMaintain Homeostasis
Each kidney has three regions1. Renal cortex
2. Renal medulla
3. Renal pelvis (where urine collects before leaving the kidney)
The nephron is the functional unit of the kidney responsible for the formation of urine
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The Nephron
The nephron performs three functions1. Glomerular filtration
2. Tubular reabsorption
3. Tubular secretion
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The Kidneys
The kidneys help regulate the pH of the blood by Reabsorbing bicarbonate ions and returning
them to the blood Removing excess hydrogen ions from the
blood
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The Kidneys
The nephrons that extend into the renal medulla are responsible for conserving water They regulate the concentration of the filtrate
as it passes through the tubules
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Kidney Function and Hormones
Antidiuretic hormone (ADH) Regulates the amount of water reabsorbed
by the distal convoluted tubules and collecting ducts of the nephrons
Aldosterone Increases reabsorption of sodium by the
distal convoluted tubules and collecting ducts in response to blood pressure
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Kidney Function and Hormones
Atrial natriuretic peptide (ANP) Released from the heart in response to
increased blood volume and pressure Relieves both of these conditions with
increased urine output and by inhibiting ADH and rennin
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Kidney Function and Hormones
The kidneys have two homeostatic functions not related to the urinary system They release erythropoietin
A hormone that stimulates the production of red blood cells
They transform vitamin D into its active form Promotes the absorption and use of
calcium and phosphorus by the body
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Dialysis and Transplant Surgery Help When Kidneys Fail
Renal failure Can be acute or chronic Results in irreversible decline in the rate of
glomerular filtration
Kidney transplants provide the recipient with a healthy kidney
Hemodialysis Use of artificial devices to cleanse the blood
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Bacteria Can Cause Urinary Tract Infections
Microorganisms can enter the urethra from the rectum or as STDs and cause urinary tract infections (UTIs)
The most common cause of UTIs in women is E. coli
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Bacteria Can Cause Urinary Tract Infections
UTIs include Urethritis
Infection of the urethra Cystitis
Infection of the bladder Pyelonephritis
Infection of the kidneys Each is serious and should be treated
immediately