BIOL 336 Lecture Notes - Lecture 22: Parasympathetic Nervous System, Somatic Nervous System, Sympathetic Nervous System
14 Aug 2016
School
Department
Course
Professor
Lecture 22: Neurobiology VIII - Neurotransmitters and Receptors of the PNS
Be able to:
1.) Identify the neurotransmitters used in PNS synapses.
2.) Identify the receptors used in PNS synapses.
3.) Describe how a given neurotransmitter can have opposing effects in different
tissues.
Recall that there are three efferent pathways in the peripheral nervous system. The first
one is the somatic nervous system. The somatic nervous system includes motor
neurons which innervate skeletal muscles. The remaining two pathways of the PNS are
the parasympathetic and sympathetic divisions of the autonomic nervous system. The
parasympathetic division is responsible for inducing the rest and digest state while the
sympathetic division is responsible for the fight-or-flight response.
Neurotransmitters in the PNS
In the Somatic branch of the PNS, the neurotransmitter released between the
somatic motor neurons and effects if Acetylcholine (ACh).
ACh is also used between pre-ganglionic and post-ganglionic neurons in
both the parasympathetic and the sympathetic branches of the
autonomic nervous system.
In the paraympathetic branch of the PNS,
the neurotransmitter released between postganglionic neurons and
effectors is ACh (like that in the Somatic NS).
In the sympathetic brach of the PNS,
the neurotransmitter released between postganglionic neurons and
effects is either epinephrine or norepinephrine.
Receptors in the PNS
The ACh rceptors (AChR) found in the Somatic and Parasympathetic NS are
distinct and differ in responsiveness to two different compounds that are
chemically similar to ACh and act as receptor agonists.
Agonists are molecules that bind to a receptor and trigger signaling
pathways. Antagonists are molecules that bind to a receptor but do not
trigger signaling pathways.
The nicotininc AChR (N-AChR) is found in the Somatic NS and responds to
nicotine found in tobacco products. They are also expressed by post-ganglionic
neurons of the autonomic nervous system.
The muscarinic AChR (M-AChR) is found in the Autonomic NS, expressed by
targets of post-ganglionic neurons. In addition to being activated by ACh, these
receptors also respond to the mushroom poison, muscarine. Atropine is an
antagonist of M-AChR).
Adrenergic receptors are activated the catecholamines epinephrine and
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture 22: neurobiology viii - neurotransmitters and receptors of the pns. Describe how a given neurotransmitter can have opposing effects in different tissues. Ach is also used between pre-ganglionic and post-ganglionic neurons in both the parasympathetic and the sympathetic branches of the autonomic nervous system. In the somatic branch of the pns, the neurotransmitter released between the somatic motor neurons and effects if acetylcholine (ach). In the sympathetic brach of the pns, the neurotransmitter released between postganglionic neurons and effectors is ach (like that in the somatic ns). Recall that there are three efferent pathways in the peripheral nervous system. The first one is the somatic nervous system. The somatic nervous system includes motor neurons which innervate skeletal muscles. The remaining two pathways of the pns are the parasympathetic and sympathetic divisions of the autonomic nervous system. The parasympathetic division is responsible for inducing the rest and digest state while the sympathetic division is responsible for the fight-or-flight response.
