SOLUTIONS TO EXERCISES, LESSON 8
1.
The urinary system is a collection of organs to rid the body of nitrogenous
wastes, created by the metabolism of proteins. These organs remove the nitrogenous
wastes from the circulating blood, concentrate them into a fluid known as urine, and
2.
A nephron begins with a renal corpuscle. The renal corpuscle is made up of a
double-walled capsule and an arterial capillary network known as the glomerulus.
Supplying blood to the glomerulus is an afferent arteriole. Draining blood from the
glomerulus is an efferent arteriole. Fluid from the blood in the glomerular capillary
passes into the space between the inner and outer walls of the capsule. (para 8-3)
3.
The fluid, called filtrate, passes through the tubular system of the nephron. As
this fluid passes through the tubular system, substances such as water and glucose are
reabsorbed and returned to the cardiovascular system. The resulting concentrated fluid
4.
At the papilla, the urine empties into the calices. The urine then flows into the
renal pelvis in the sinus of the kidney. The urine then moves along the ureters drop by
5.
The urinary bladder is highly specialized to store urine until it is eliminated from
the body. Thus, except for the trigone, the wall of the urinary bladder is very
stretchable.
When the transitional epithelium reaches the limit of its stretchability, a message
is sent to initiate the voiding reflex. There can be several increments of stretching until
the limit of the urinary bladder is reached. (para 8-6)
6.
The urethra is the single tubular structure that connects the urinary bladder to the
outside. The female urethra is relatively short and straight. The male urethra has two
more-or-less right-angle turns.
Two muscular structures preventing urine from leaving the urinary bladder are
the urethral sphincters. Urine is forced through them when the sphincters relax.
End of Lesson 8
MD0007
8-8