Chapter 29 By: Joe Sinicropi
The parasympathetic nervous system is one of three divisions of the autonomic nervous system. Sometimes called the rest and digest system, the parasympathetic system conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.
Sensory neurons are nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses. For example, some sensory neurons respond to tactile stimuli and can activate motor neurons in order to achieve muscle contraction.
Sensory neurons are nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses. For example, some sensory neurons respond to tactile stimuli and can activate motor neurons in order to achieve muscle contraction.
Acetylcholine is an organic chemical that functions in the brain and body of many types of animals, including humans, as a neurotransmitter—a chemical released by nerve cells to send signals to other cells.
Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively. They are the flight/fight hormones that are released when the body is under extreme stress. During stress, much of the body's energy is used to combat imminent danger.
a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
White matter: White matter is composed of bundles of myelinated nerve cell projections (or axons), which connect various gray matter areas (the locations of nerve cell bodies) of the brain to each other, and carry nerve impulses between neurons. Gray matter: the darker tissue of the brain and spinal cord, consisting mainly of nerve cell bodies and branching dendrites.
