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Excretory and Urinary System Notes Chapter 15
Functions of the Urinary SystemFunctions of the Urinary System
Slide 15.1aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Elimination of waste products Nitrogenous wastes
Toxins
Drugs
Functions of the Urinary SystemFunctions of the Urinary System
Slide 15.1bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Regulate aspects of homeostasis Water balance
Electrolytes
Acid-base balance in the blood
Blood pressure
Red blood cell production
Activation of vitamin D
Organs of the Urinary systemOrgans of the Urinary system
Slide 15.2Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Kidneys
Ureters
Urinary bladder
Urethra
Figure 15.1a
Location of the Kidneys p 481Location of the Kidneys p 481
Slide 15.3Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Against the dorsal body wall
At the level of T12 to L3
The right kidney is slightly lower than the left
Attached to ureters, renal blood vessels, and nerves at renal hilus
Atop each kidney is an adrenal gland
Coverings of the KidneysCoverings of the Kidneys
Slide 15.4Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Renal capsule Surrounds each kidney
Adipose capsule Surrounds the kidney
Provides protection to the kidney
Helps keep the kidney in its correct location
Regions of the Kidney p 482Regions of the Kidney p 482
Slide 15.5Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Renal cortex – outer region
Renal medulla – inside the cortex
Renal pelvis – inner collecting tube
Figure 15.2b
UretersUreters
Slide 15.20Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slender tubes attaching the kidney to the bladder
Continuous with the renal pelvis
Enter the posterior aspect of the bladder
Runs behind the peritoneum
Peristalsis aids gravity in urine transport
Urinary BladderUrinary Bladder
Slide 15.21aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Smooth, collapsible, muscular sac
Temporarily stores urine
Figure 15.6
Urinary Bladder WallUrinary Bladder Wall
Slide 15.22Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Three layers of smooth muscle (detrusor muscle)
Mucosa made of transitional epithelium
Walls are thick and folded in an empty bladder
Bladder can expand significantly without increasing internal pressure
UrethraUrethra
Slide 15.23Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis
Release of urine is controlled by two sphincters
Internal urethral sphincter (involuntary)
External urethral sphincter (voluntary)
Nephron Function – “functional unit of the kidney”
Three Processes – Page 4861. Filtration
(blood to capsule)2. Reabsorption
(return to blood)3. Excreted products
(added to urine)
Filtration p 487 Urine formation occurs in millions of units called
nephrons.1. Unfiltered blood enters the renal artery into smaller
arterioles.2. Blood then enters the glomerulus – mass of
capillaries where blood is filtered.3. Large molecules – red and white blood cells,
platelets, plasma proteins, and fats stay in the glomerulus and return through smaller venules into the renal vein
4. Smaller molecules – water, amino acids, salt, glucose, and urea get filtered into the Bowman’s Capsule and travels into the tubules, eventually into the collecting duct
Reabsorption
1. Too much is filtered so amino acids, sugars, and water are reabsorbed depending on what is needed by the body
2. Urine- what’s left over – urea, uric acid, excess water and salt
Excreted Products
Through the process of excretion, almost 100% of nutrients are reabsorbed and essentially all wastes are excreted. Ammonia is extremely toxic to the body and must be constantly flushed from the system
Other excretory organs
Skin – (Perspiration) – get rid of water, salts, and urea.
Lungs – Respiration – excrete CO2 Liver – forms urea when producing bile