After their manufacture, sperm cells are stored in a much-coiled tube on the surface of each testis, the epi-didymis (see Figs. 14-1 and 14-2). Here they remain until ejaculation propels them into a series of ducts that lead out of the body. The first of these is the vas (ductus) deferens. This duct ascends through the inguinal canal into the abdominal cavity and travels behind the bladder. A short continuation, the ejaculatory duct, delivers the spermatozoa to the urethra as it passes through the prostate gland below the bladder. Finally, the cells, now mixed with other secretions, travel in the urethra through the penis to be released. The penis is the male organ that transports both urine and semen. It enlarges at the tip to form the glans penis, which is covered by loose skin, the prepuce or foreskin. Surgery to remove the foreskin is circumcision. This may be performed for medical reasons, but is most often performed electively in male infants for reasons of hygiene, cultural preferences, or religion.
BOX 14-1 Which Is It?
Some of the work of learning medical terminology is made more difficult by the fact that many structures and processes are known by two or even more names. This duplication may occur because different names have been assigned at different times or places or because the name is in a state of transition to another name and the new one has not been universally accepted.
The tube that leads from the testis to the urethra in males was originally called the vas defer-ens, vas being a general term for vessel. To distinguish this tube from a blood vessel, efforts have been made to change the name to ductus deferens. The original name has lingered, however, because the surgical procedure used to sterilize a man is still called a vasectomy and not a "ductusectomy."
Similar inconsistencies appear in other systems. Dorsal is also posterior; ventral could be anterior. Human growth hormone is also called somatotropin. LH (luteinizing hormone) is called ICSH (interstitial cell-stimulating hormone) in the male.
In the nervous system, the little swellings at the ends of axons that contain neurotransmit-ters are variously called end-feet, end-bulbs, terminal knobs, terminal feet, and even more. In the woman, the tube that carries the ovum from the ovary to the uterus is referred to as the oviduct, or maybe the Fallopian tube. . . or the uterine tube. . . or. . . .
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.