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Chapter 2

PSY333H1 Chapter Notes - Chapter 2: Parasympathetic Nervous System, Sympathetic Nervous System, Autonomic Nervous System

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Nevena Simic

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PSY333 Health Psychology
Chapter 2 The Systems of the Body
The nervous system is a complex network of interconnected nerve fibers
that functions to regulate many important bodily functions
o Made up of the central nervous system and peripheral nervous system
o CNS consists of the brain and spinal cord
o The rest of the nerves in the body, including those that connect to the
brain and spinal cord, constitute the PNS
o The PNS is made up of the somatic nervous system and autonomic
nervous system
o Somatic nervous system is the voluntary nervous system that connect
nerve fibers to voluntary muscles and provides the brain with
feedback in the form of sensory information about voluntary
o Autonomic, or involuntary, connects the CNS with all internal organs
over which people do not customarily have control
Regulation of the autonomic nervous system occurs via the sympathetic
nervous system and the parasympathetic nervous system
Sympathetic nervous system prepares the body to respond to emergencies;
strong emotions; and strenuous activity (especially stress)
o Because it’s concerned with the mobilization and exertion of energy,
it’s called a catabolic system
Parasympathetic nervous system controls activities of organs under
normal circumstances and acts incompatible to the sympathetic nervous
system when emergency passes, it restores the body to a normal state
o Common during digestion; can lead to relaxation and drowsiness
o Because it’s concerned with conservation of body energy, it’s called an
anabolic system
Brain receives afferent (sensory) impulses from the peripheral nerve endings
and sends efferent (motor) impulses to the extremities and to internal organs
to carry out necessary movement
Brain consists of 3 sections: hindbrain, midbrain, forebrain
o Hindbrain has 3 parts: medulla, pons, and cerebellum
o The medulla receives information about the rate at which the heart is
contracting, and speeds up or slows down the heart rate as required;
also receives information about blood pressure, CO2 in the blood and
oxygen in the body to regulate blood vessels and breathing rate
o The pons serve as a link between the hindbrain and the midbrain;
also helps control respiration
o The cerebellum coordinates voluntary muscle movement, the
maintenance of balance and equilibrium, and the maintenance of
muscle tone and posture
o Midbrain is the major pathway for sensory and motor impulses
moving between forebrain and hindbrain, also responsible for the
coordination of visual and auditory reflexes
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