pg 11 Flashcards
What are the two divisions of the Motor Division of the PNS?
Somatic and Autonomic
b. What body organs and/or structures do each of these divisions control?
Somatic: Controls skeletal muscle contractions only. Autonomic: Controls all
unconsciously controlled body functions, such as cardiac and smooth muscle
contractions, activities of all organs and glands
c. How does the nerve composition differ in these two divisions?
Somatic: One neuron that starts at brain or spinal cord and reaches organ.
Autonomic: Two neurons that synapse at a ganglia. The second neuron reaches organ.
(See images on page 6.)
How does the type of control differ in these two divisions?
Skeletal muscle control is consciously controlled by the somatic nervous system. In other
words, somatic nerves control the one thing we can think about & cause to happen—
skeletal muscle contraction.
All activities of the autonomic nervous system are involuntary, or unconsciously
controlled—the heartbeat (cardiac muscle), smooth muscle, organ activities, blood flow,
etc.
Norepinephrine (NE), or noradrenalin (NA), is another example of a NT
that can cause_____ or _____ effects
excitatory , Inhibitory
Give an example of how NA causes excitatory effects in some blood
vessels but inhibitory effects in other blood vessels.
The basic job of NA is to increase physical activity (contraction of skeletal muscle and
other processes that go along with exercising). NA is responsible for “Fight or Flight”
activities.
Therefore, NA has excitatory effects in skeletal muscle blood vessels because it
increases blood flow to skeletal muscles (vasodilation). However, NA has inhibitory
effects in skin and organ blood vessels because it reduces the blood flow to those
locations (vasoconstriction).
b. What is the general name for NA receptors?
Adrenergic receptors
c. How is it possible for NA to have excitatory effects in one location but
inhibitory effects in another location?
Because there are two specific types of adrenergic receptors, alpha and beta.
In general, the effect of NA is dependent upon which receptor type (alpha or beta) it binds
to. For example, when NA binds to alpha receptors in blood vessels, the effect is
inhibitory (decreased blood flow). When NA binds to beta receptors in blood vessels, the
effect is excitatory (increased blood flow).
What does NA cause to happen in the liver that goes along with
increased physical activity
NA causes the liver to release sugar (glucose) so that it can be used to make energy
(ATP) for skeletal muscle contraction.
How are the Sympathetic and Parasympathetic Nervous Systems different
in the locations that their nerves exit the spinal cord?
Sympathetic—Nerves exit at the thoracic and lumbar regions of the spinal cord.
Parasympathetic—Nerves exit at the brainstem and sacral regions of the spinal cord.
(See bottom diagram on the next page.)
What are ganglia?
Ganglia are synapses (connections) between neurons that occur outside of the brain or
spinal cord. They occur in both the Sympathetic and Parasympathetic Nervous Systems.
In other words, ganglia are where the first neuron that leaves the spinal cord connects
with a second neuron that is out in the body cavity. The first nerve that leaves the spinal
cord is called the preganglionic neuron (1) while the second is called the postganglionic
neuron (2).
(See top diagram on the next page.)
c. How are the Sympathetic and Parasympathetic Nervous Systems different
in the locations of their ganglia?
Sympathetic—Ganglia are near spinal cord.
Parasympathetic—Ganglia are near organs (far from the spinal cord).
How does the location of ganglia affect the length of the preganglionic and
postganglionic neurons of the Sympathetic and Parasympathetic Nervous
Systems? (See diagrams on page 13)
Sympathetic—Preganglionic neurons are short (since ganglia are close to spinal cord),
postganglionic neurons are long so that they can reach organs.
Parasympathetic—Preganglionic neurons are long (since ganglia are near organs),
postganglionic neurons are short.
