Flashcards in Peripheral Nervous System Deck (226)
What are the two primary divisions of the peripheral nervous system?
somatic (sensory and motor) and autonomic (sympathetic and parasympathetic)
The somatic nervous system send motor or _______ impulses to skeletal muscle. Somatic sensory nerves carry impulses (or ________) that are perceived, such as touch, pressure, pain, and temperature.
What is the predominant neurotransmitter in the periphery?
What is the difference in preganglionic and post ganglionic nerves in the parasympathetic neurons vs the sympathetic neurons?
sympathetic preganglionic nerves tend to have short lengths and postganglionic tend to be longer; parasympathetic has the OPPOSITE--- long pre, short post
In regards to pre and post ganglionic nerves... what is different about the adrenal medulla?
the adrenal medulla does not have post ganglionic fibers... only PRE.... so there is a direct release of the hormones (EPI, NE)
What is the primary neurotransmitter found in the pre and post ganglionic neuron of the sympathetic nervous system?
What is the primary neurotransmitter in the pre and post ganglionic neuron of the parasympathetic nervous system?
Acetylcholine is the neurotransmitter released from somatic ______ nerves, ________ sympathetic nerves, ________ parasympathetic nerves, and _______ parasympathetic nerves.
Acetylcholine is the neurotransmitter released from somatic motor nerves, preganglionic sympathetic nerves, preganglionic parasympathetic nerves, and postganglionic parasympathetic nerves.
With one exception, norepinephrine is released from ALL sympathetic postganglionic nerves. The exception is _______.
sweat glands; AcH, not NE is released to sweat glands from sympathetic postganglionic nerves
What neurotransmitter released from the sympathetic neurons is responsible for triggering the release of hormones from the adrenal medulla?
acetylcholine..... BECAUSE the adrenal medulla is innervated by sympathetic PREGANGLIONIC neurons
What receptors are found on tissues innervated by the parasympathetic nervous system?
muscarinic receptors (cholinergic)
What receptors are found on tissue innervated by the sympathetic nervous system? The exception is the ______ ______.
adrenergic receptors; exception is the sweat glands.... where acetylcholine is released from the sympathetic postganglionic neuron to muscarinic receptors.
Where can nicotinic receptors be found?
found at the autonomic ganglia, on cells of the adrenal medulla, and at the motor-end plate of skeletal muscle
What receptor is responsible for possible bradycardia after the administration of succinylcholine?
muscarinic receptors on SA node
Alpha 1, alpha 2, and beta 1 are all examples of ______ receptors.
Does norepinephrine stimulate beta 2 receptors?
NO..... beta 2 is stimulated by epinephrine
Acetylcholine binds to nicotinic receptors except for the postganglionic neurons of the ________ nervous system.
parasympathetic; at the tissues of the PNS postganglionic.... but AcH still binds to nicotinic receptors in the PRE ganglionic parasympathetic neurons.
Where are nicotinic receptors found?
peripherally in the motor end plate of skeletal muscle and in cell bodies of both sympathetic and parasympathetic postganglionic neurons; nicotinic receptors respond to ACh or ACh agonists (sux) in a biphasic fashion
Nicotinic receptors respond to ACh or ACh agonists (sux) in a biphasic fashion. What does this mean in regards to dose?
in small doses, ACh stimulates nicotinic receptors of postganglionic sympathetic and parasympathetic neurons as well as nicotinic receptors of skeletal muscle end plate to cause depolarization; BUT IN HIGH DOSES or PROLONGED EXPOSURE, the nicotinic receptors become desensitized to succinylcholine and the postsynaptic membrane becomes inexcitable; this is called a PHASE II block
What are the 2 major subtypes of cholinergic receptors?
nicotinic and muscarinic
Cholinergic is the abbreviated term referring to __________.
acetylcholine; acetylcholine receptors are nicotinic and muscarinic
A substance (or ligand) is ________ if it is capable of producing, altering, or releasing acetylcholine ("indirect-acting") or mimicking its behaviour at one or more of the body's acetylcholine receptor types ("direct-acting").
List the "fiber types" in order from largest to smallest diameter.
A-alpha (largest and fastest), A-beta, A-gamma, A-delta, B, sC, dC (smallest and slowest)
What fiber types are myelinated?
ALL of the A fibers (alpha, beta, gamma, delta) & B; sC, dC are UNMYELINATED
Which fibers carry sensations of sharp, prickling pain and temperature?
Which fibers carry sensations of throbbing pain and temperature?
dC fibers (sensory afferent)..... they are smaller so you get a slow throbbing pain
What is the function of A-alpha fibers?
motor (efferent) and sensory (afferent) to skeletal muscle and joints; muscle length, muscle force, proprioception
What two fibers are responsible for proprioception?
A-alpha and A-beta sensory fibers
Sympathetic and parasympathetic (both autonomic) preganglionic neurons are _____ fibers.