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Copyright 2003 by Mosby, Inc. All rights reserved.
CHAPTER 16
URINARY SYSTEM
Copyright 2003 by Mosby, Inc. All rights reserved.
Structure and Function
• The functions of the urinary system are to:– Filter about 180 liters of blood plasma
daily – Form and excrete urine daily to remove
waste products– Regulate the chemical composition of
body fluids– Remove body wastes by filtering blood
Copyright 2003 by Mosby, Inc. All rights reserved.
Kidneys
• Each kidney is about 4 inches long and 2 inches wide, and weighs about 150 g
• Each kidney contains about 1 to 2 million nephrons (tiny structures that filter the blood)
• The kidney has three layers – Cortex – Medulla – Renal pelvis
Copyright 2003 by Mosby, Inc. All rights reserved.
Figure 16-3 The Kidney
Copyright 2003 by Mosby, Inc. All rights reserved.
Additional Components of the Urinary System • Ureters
– Small tubes composed of smooth muscle tissue, move the urine from the kidney to the bladder with peristaltic motion
• Bladder– A smooth muscular sac that expands as it
fills with urine
• Urethra– Moves urine from the bladder to be
excreted from the body
Copyright 2003 by Mosby, Inc. All rights reserved.
Urine Formation
• Every minute blood plasma enters the nephrons of each kidney through the renal arteries
• In the nephron, particles are filtered from the blood to be eliminated by the body
• Water, glucose, vitamins, amino acids, and chloride salts are reabsorbed into the blood in the renal tubules
• Ammonia, potassium, hydrogen ions, and some drugs are secreted into the urine
• The blood leaves the kidneys in the renal veins
Copyright 2003 by Mosby, Inc. All rights reserved.
Table 16-2 Characteristics of Urine
Copyright 2003 by Mosby, Inc. All rights reserved.
Assessment Techniques
• Urinalysis • Radiological examination (KUB) • Intravenous pyelogram (IVP) • Cystoscopy • Urodynamic tests • Electromyography (EMG)
Copyright 2003 by Mosby, Inc. All rights reserved.
Disorders of the Urinary System • Cystitis
– Inflammation of the bladder caused by many different types of bacteria
• Edema – An abnormal accumulation of fluid in the
tissue intercellular space
• Nephritis– Inflammation of the kidneys
• Renal calculus – A kidney stone
Copyright 2003 by Mosby, Inc. All rights reserved.
Disorders of the Urinary System (continued)
• Renal failure – The absence of urine formation
• Uremia – A condition in which the kidneys do not filter
the blood
• Urethritis– Acute or chronic inflammation of the urethra
• Urinary incontinence – The inability to control urination
Copyright 2003 by Mosby, Inc. All rights reserved.
Disorders of the Urinary System (continued)
• Urinary retention– The inability to urinate when the urge is felt
or the bladder is full
• Urinary tract infection – Usually caused by bacteria, and may affect
the bladder, kidneys, or prostate
Copyright 2003 by Mosby, Inc. All rights reserved.
Issues and Innovations • Dialysis
– Filtration of body fluids through a machine instead of the kidneys
• Kidney transplant – Drawbacks include matching tissues, expense, and shortage of donors– High success rate
• Lithotripsy– Disintegrates kidney stones– Prevents need for surgery to remove stone
