777
CHAPTER TWENTY
Urinary System
substances that would normally be excreted in the urine. A
patient usually must use this artif
cial kidney three times a
week, For several hours each time. Clinical Application 20.1
Further discusses hemodialysis.
PRACTICE
1
Where are the kidneys located?
2
Describe the structure of a kidney.
3
What are the general functions of the kidneys?
them to the outside. These wastes include nitrogenous and
sulFur-containing products oF protein metabolism. The kid-
neys also help control the rate oF red blood cell Formation
by secreting the hormone
erythropoietin
(see chapter 14,
p. 527), regulate blood pressure by secreting the enzyme
renin
(see chapter 13, p. 506), and regulate absorption oF cal-
cium ions by activating
vitamin D
(see chapter 18, p. 717).
Medical technology can take over some oF the roles oF
a kidney. In
hemodialysis,
a person’s blood is rerouted
across an artif cial membrane that “cleanses” it, removing
Parietal
peritoneum
Inferior vena cava
Pancreas
(a)
(b)
Adrenal gland
Twelfth rib
Kidney
Adipose tissue
Kidney
Spleen
Large intestine
Small intestine
Aorta
Stomach
Liver
Parietal peritoneum
Renal fascia
Renal fascia
Large intestine
Hip bone (cut)
FIGURE 20.3
The kidneys are located retroperitoneally. (
a
) Transverse section through the posterior abdominal cavity including the kidneys,
behind the parietal peritoneum. Adipose and other connective tissues surround and support the kidneys. (
b
) Sagittal section through the posterior
abdominal cavity showing the kidney.
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