184 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”has to be an intervening brain mechanism, of whose workings the agent
may or may not be aware, that evaluates the survival value of the object
perceived with respect to self, the outcome of which evaluation results
in the intensity of the physiological reactions; the intensity being propor-
tional to the degree of positivity or negativity of the valuation.
9.4 Autonomic Nervous System and the Hypothalamus
Some important events took place in the ensuing fifty years following
the formulation of the James-Lange theory. One was the discovery of
the autonomic nervous system and its relation to the hypothalamus. The
other was the discovery of the “emotional centers” in the brain.
It has been known for a long time that not all activities of the ani-
mal body are under volitional control. For example, your heart beats
75 times a minute, your breathing goes on whether you are awake or
asleep, and you sweat profusely when the weather gets hot, all without
your conscious effort. Such involuntary, relatively stereotyped activi-
ties are under the control of two opposing forces, together called the
autonomic nervous system (Fig. 9.1). One part, called the sympathetic
nervous system, is responsible for the expenditure of energy in times
of heightened awareness or emergency; the other, called the parasym-
pathetic nervous system, is responsible for restoration and conservation
of energy in restful times. The sympathetic responses include: widening
of the pupils, thirst, acceleration of the heart, rise in blood pressure,
rapid shallow respiration, dilatation of the bronchioles, constriction of
the arterioles (except those in skeletal muscles), sweating in the palms,
increased level of blood sugar, inhibition of gastrointestinal and urinary
functions, and increased skeletal muscle tone. All these changes enable
the subject to escape danger, to overpower an opponent, or to procure
a delicious meal. The parasympathetic responses are the opposite of the
above. The autonomic nervous system not only expresses its responses
on the end organs, but also reports back from the end organs to the brain
via sensory fibers on a conscious level, thus producing the sensation of
palpitation, sweating, abdominal cramps, etc., during stress.