This chapter is about the urinary system, which
plays a vital role in maintaining the internal environment by excreting nitrogenous
waste products and by selectively excreting or retaining water and electrolytes.
It identifies, locates, and describes the functions of the organs of the urinary
system (objectives 1-3). It explains the structure and function of the nephron--the
basic unit of function of the kidney (objective 5). It traces the pathway of
blood through the blood vessels of the kidney, explains how glomerular filtrate
is produced, and discusses the role of tubular reabsorption in urine production
and the cause of change in the osmotic concentration of the glomerular filtrate
of the renal tubule (objectives 4 and 6-10). It also describes the role of tubular
secretion in urine formation (objective 11). It discusses the structure of the
ureters, urinary bladder, and urethra, and how they function in micturition
(objectives 12 and 13).
A study of the urinary system is basic to understanding
how the body maintains its chemistry within very narrow limits.