Ch 13: Physiology of the Peripheral Nervous System Flashcards
What are the two major subdivisions of the peripheral nervous system?
Somatic motor system
Autonomic nervous system
(p. 102)
The autonomic nervous system is further subdivided into the…
parasympathetic and sympathetic nervous systems.
p. 102
What are the 3 principal functions of the autonomic nervous system?
- regulation of the heart
- regulation of secretory glands (B-G-S-S) (bronchial, gastric, salivary, and sweat glands)
- regulation of smooth muscles (in blood vessels, bronchi, GI tract, and, urogenital system)
(p. 102)
What are 7 regulatory functions performed by the parasympathetic nervous system which have particular relevance to drugs?
- slowing of heart rate
- contracting bronchial smooth muscle
- increased gastric secretion
- emptying of the bowel
- emptying of the bladder
- focusing the eye for near vision
- constricting the pupil
(p. 102)
The sympathetic nervous system has 3 main functions:
- regulating the cardiovascular system
- regulating body temperature
- implementing the acute stress (“fight-or-flight”) response
(p. 103)
In what 3 ways do the sympathetic nervous system help regulate body temperature?
- by regulating blood flow to the skin, sympathetic nerves can increase or decrease heat loss
- sympathetic nerves to sweat glands promote secretion of sweat, thereby helping the body cool
- by inducing piloerection, sympathetic nerves can promote heat conservation
(p. 103)
What are the 5 events which make up the fight-or-flight response?
- increasing HR and BP
- shunting blood away from the skin and viscera and into skeletal muscles
- dilating the bronchi to improve oxygenation
- dilating the pupils (perhaps to enhance visual acuity)
- mobilizing stored energy, thereby providing glucose for the brain and fatty acids for muscles
(p. 103)
What is feedback regulation?
The process that allows a system to adjust itself by responding to incoming information.
(p. 103)
From a pharmacologic perspective, the most important feedback loop of the autonomic nervous system is…
…the baroreceptor reflex
p. 104
The branch of the autonomic nervous system that controls organ function most of the time is said to provide the ___________ ____ to that organ.
predominant tone
p. 104
There are 2 neurons in the pathway leading from the spinal cord to organs innervated by parasympathetic nerves. The junction, or synapse, between these 2 neurons occurs within a structure called a…
…ganglion.
p. 104
What is a ganglion?
a mass of nerve cell bodies
p. 104
What are the nerves cells that go from the spinal cord to the parasympathetic ganglia?
What are the nerves cells that go from the ganglia to effector organs?
preganglionic neurons
postganglionic neurons
(p. 104)
The anatomy of the parasympathetic nervous system offers two general sites at which drugs can act:
(1) The synapses between preganglionic neurons and postganglionic neurons, and (2) the junctions between postganglionic neurons and their effector organs.
(p. 104)
Although the adrenal medulla is not a neuron per se, it can be looked on as the functional equivalent of…
…a postganglionic neuron of the sympathetic nervous system.
(p. 104)
Because the adrenal medulla is similar in function to a postganglionic neuron, the nerve leading from the spinal cord to the adrenal gland is commonly referred to as a…
…preganglionic neuron, even though there is no ganglion in this pathway.
(p. 104)
How many neurons are in the pathway from the spinal cord to the muscles innervated by somatic motor nerves?
What is the implication of this?
only one
Peripherally acting drugs that affect somatic motor system function have only one site of action: the neuromuscular junction.
(p. 105)
The PNS uses 3 primary neurotransmitters, (and a 4th whose role has not been demonstrated conclusively). What are these 4?
Any given junction in the PNS uses only ___ of these transmitters.
acetylcholine
norepinephrine
epinephrine
dopamine
one
(p. 105)
At which specific junctions is acetylcholine used?
- all preganglionic neurons of the parasympathetic nervous system (PNS) and sympathetic nervous system (SNS)
- all postganglionic neurons of the PNS
- most postganglionic neurons of the SNS that innervate sweat glands
- all motor neurons to skeletal muscles (somatic motor system)
(p. 106)
At which specific junctions is norepinephrine used?
- almost all postganglionic neurons of the sympathetic nervous system (the exception is postganglionic neurons of the SNS that innervate sweat glands)
- the adrenal medulla releases some norepinephrine
(p. 106)
At which specific junction is epinephrine used?
the adrenal medulla
p. 105
What are cholinergic receptors?
Receptors that mediate responses to acetylcholine
p. 105
What are adrenergic receptors?
Receptors that mediate responses to epinephrine (adrenaline) and norepinephrine
(Dopamine receptors are also classified as adrenergic receptors, but they respond only to dopamine, not to epi and norepi)
(p. 105)
What are the 3 major subtypes of cholinergic receptors?
nicotinic N
nicotinic M
muscarinic
(p. 106)
What are the 4 major subtypes of adrenergic receptors?
In addition to these 4, what adrenergic receptor type is found primarily in the CNS?
alpha 1
alpha 2
beta 1
beta 2
dopamine
(p. 106)
Drugs achieve their selectivity for receptor subtypes by having structures that are…
…different from those of natural transmitters.
p. 107