Page 1001 - Fundamentals of anatomy physiology

988 Unit 5 Environmental Exchange
25 Clinical Note
Alcohol Alcohol production and sales are big business
throughout the world. We see beer commercials on televi-
sion, billboards advertising various brands of liquor, and TV or
movie characters enjoying a drink. All demonstrate the promi-
nence of alcohol in many societies. Many people are unaware
of the medical consequences of this cultural fondness for
alcohol. Problems with alcohol are usually divided into those
stemming from alcohol abuse and those involving alcohol-
ism. The boundary between these conditions is hazy. Alcohol
abuse is the general term for overuse and its behavioral and
physical effects. Alcoholism is chronic alcohol abuse accompa-
nied by the physiological changes associated with addiction
to other CNS-active drugs. Alcoholism has received the most
attention in recent years, but alcohol abuse—especially when
combined with driving a car—is also in the spotlight.
Consider these statistics provided by the CDC and the
National Council on Alcoholism and Drug Dependence for
people living in the United States:
One in four children—over 7 million—grows up in a home
where somebody abuses alcohol.
17.6 million people—1 in every 12 adults—abuse alcohol.
79,000 deaths are attributed to alcohol use annually.
Alcoholism remains the third leading cause of lifestyle-
related deaths.
Some major clinical conditions are caused almost entirely
by alcohol consumption. For example, alcohol is responsible
for 60–90 percent of all liver disease in the United States.
Alcohol affects all physiological systems. Major clinical
symptoms of alcoholism include (1) disorientation and con-
fusion (nervous system); (2) ulcers, diarrhea, and cirrhosis
(digestive system); (3) cardiac arrhythmias, cardiomyopathy,
and anemia (cardiovascular system); (4) depressed sexual
drive and testosterone levels (reproductive system); and
(5) itching and angiomas (benign blood vessel or lymphatic
vessel tumors) (integumentary system).
The toll on newborn infants has risen steadily since the
1960s as the number of female drinkers has increased.
25-7 Metabolic rate is the
average caloric expenditure, and
thermoregulation involves balancing
heat-producing and heat-losing
mechanisms
Learning Outcome Define metabolic rate, discuss the factors involved and expenditure. Then we turn to the topic of thermoregulation.
in determining an individual’s BMR, and discuss the homeostatic
mechanisms that maintain a constant body temperature.
A person’s daily energy expenditures vary widely with activ-
ity. For example, a person leading a sedentary life may have
Women who consume 1 ounce of alcohol per day during
pregnancy have a higher rate of spontaneous abortion and
bear children with lower birth weights than do women who
consume no alcohol. Women who drink heavily may have
children with fetal alcohol syndrome (FAS). Facial abnormali-
ties, a small head, slow growth, and mental retardation
characterize this condition.
Alcohol abuse is considerably more widespread than alco-
holism. The medical effects are less well documented, but
they are clearly significant.
Several factors interact to produce alcoholism. The pri-
mary risk factors are sex (males are more likely to become
alcoholics than are females) and a family history of alcohol-
ism. There does appear to be a genetic component: A gene
on chromosome 11 has been implicated in some inherited
forms of alcoholism. The relative importance of genes versus
social environment has been difficult to assess. It is likely
that alcohol abuse and alcoholism result from a variety of
factors.
Treatment may consist of counseling and behavior
modification. To be successful, treatment must include total
avoidance of alcohol. Support groups, such as Alcoholics
Anonymous (AA), can be very helpful in providing a social
framework for abstinence. The drug disulfiram (Antabuse)
sensitizes an individual to alcohol such that a drink produces
intense nausea. Unfortunately, it has not proved to be as ef-
fective a deterrent as originally anticipated. Clinical tests indi-
cated that it could increase the time between drinks but could
not prevent drinking altogether.
Another drug, naltrexone (ReVia, Depade, and injectable
Vivitrol), has shown promise in reducing the frequency and
severity of drinking relapses in alcoholics. Naltrexone is an
opioid receptor antagonist. It blocks the part of the brain that
elicits pleasurable feelings after the consumption of alcohol.
The result is a decreased craving for alcohol, enabling indi-
viduals to stop drinking more readily. Unlike Antabuse, it does
not cause nausea.
minimal energy demands, but a single hour of swimming can
significantly increase daily energy use. If your daily energy in-
take exceeds your total energy demands, you store the excess
energy, primarily as triglycerides in adipose tissue. If your daily
energy expenditures exceed your intake, the result is a net reduc-
tion in your body’s energy reserves and a corresponding loss in
weight. In this section, first we consider aspects of energy intake
Energy Gains and Losses
When chemical bonds are broken, energy is released. Inside
cells, a significant amount of energy may be used to synthesize