Essentials of Anatomy and Physiology

CHARACTERISTICS OF URINE

The characteristics of urine include the physical and
chemical aspects that are often evaluated as part of a
urinalysis. Some of these are described in this section,

and others are included in Appendix D: Normal

Values for Some Commonly Used Urine Tests.

Amount—normal urinary output per 24 hours is 1

to 2 liters. Many factors can significantly change

output. Excessive sweating or loss of fluid through

432 The Urinary System

Internal

urethral sphincter

External

urethral sphincter

Urethra

Urethral orifice

Trigone

Ureter

Trigone

Rugae

Openings of

ureters

Detrusor muscle

Parietal peritoneum Ureter

Prostate gland

Prostatic urethra

Membranous

urethra

Cavernous (spongy)

urethra

Cavernous (erectile)

tissue of penis

A

B

Figure 18–7. (A) Frontal section of female urinary bladder and urethra. (B) Frontal sec-

tion of male urinary bladder and urethra.

QUESTION:Name the sphincters of the urinary system and state whether each is volun-

tary or involuntary.