The Nervous System: The Brain, Cranial Nerves, Autonomic Nervous System, and the Special Senses 267
As the body Ages
The nervous system forms very quickly in the developing embryo. By the first
month, a brain and spinal cord can be seen with the beginnings of sense or-gans.
When a child is born, the head is much larger in proportion to the rest of the body
due to the developed nervous system and its neurons.^
As we grow, the brain develops very rapidly during the first years of life as
the neurons increase in size. The supporting cells or neuroglia grow and increase
in numbers, and certain neurons develop myelinated sheaths while their dendrite
branches develop and increase in number resulting in more syn-apse contacts.
At maturity, the nervous system begins to undergo numerous changes. The brain actu-ally
begins to decrease in size and mass due to a loss of neurons that constitute the outer part of the
cerebrum. Individuals in their mid-70s lose 7% of the weight of their brain. Accompa-nying this is
a loss in synaptic contacts and neurotransmitters. This results in a diminished capacity to send
impulses to and from the brain. Information processing is more difficult and muscular movement
and responses slow down. These are all symptoms observed in older adults. A reduction in the
size of the arteries supplying the brain results in less oxygen carry-ing blood supplying these
cells, increasing the possibilities of strokes in older adults supply-ing these cells increasing the
possibilities of strokes in older adults.Career
Focus
These are careers that are available to individuals who are interested in working with
nervous system.^
● Anesthesiologists are physicians who administer anesthesia directly to patients during
surgery or supervise nurse anesthetists in the delivery of anesthesia.^
● Anesthesiologist assistants are allied health professionals who acquire preopera-tive
information such as a history of health-related problems and perform physical
examinations such as insertion of intravenous injections and catheters as well as being
involved in recovery room care.^
● Neurosurgeons are physicians specializing in surgery of the brain, spinal cord, and
the peripheral nerves.^
● Nurse anesthetists are registered nurses who have advanced training in anesthe-sia
and who manage the care of patients during the administration of anesthesia in certain
surgical situations.^
● Acupuncturists are individuals trained in the traditional Chinese method of dull-ing
pain by inserting fine wire needles into the skin at specific sites to produce an
anesthetic effect on certain parts of the body.^
● Psychiatrists are physicians with advanced training in the diagnosis, prevention, and
treatment of mental disorders.^
● Psychologists are individuals who specialize in the study of the function of the brain.
Clinical psychologists provide testing and counseling for patients with emo-tional and
mental disorders and have graduate training.