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Anatomy & Physiology Exam 3
Efferent Division of the Peripheral Nervous System
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Anatomy
04/13/2010

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Term
what does the efferent division of the peripheral nervous system consist of?
Definition
-a system motor neurons that is further divided into somatic & autonomic parts
Term
what are the effectors of the somatic part of the efferent division?
Definition
-skeletal muscle
Term
what are the effectors of the autonomic part of the efferent division?
Definition
-smooth & cardiac muscle, glands
Term
-what is the pathway for the somatic part of the efferent division?
-autonomic?
Definition
-somatic pathway: single neuron
-autonomic pathway: 2 neuron chain with a synapse in between
Term
what are the neurotransmitters for the somatic parts of the efferent division? autonomic?
Definition
-somatic neurotransmitters: acetylcholine only
-autonomic: acetylcholine, norepinephrine, epinephrine
Term
what is the neurotransmitter effect on target cell for the somatic/autonomic parts of the efferent division?
Definition
-somatic: acetylcholine is always excitatory
-autonomic: excitatory or inhibitory
Term
what is a target cell?
Definition
-similar to effector
Term
what is cholinergic?
Definition
refers to something that is associated with acetylcholine (in efferent division of peripheral nervous system)
Term
what is adrenergic?
Definition
-refers to something that is associated with epinephrine and norephinephrine (in efferent division of peripheral nervous system)
Term
what are cholinergic fibers?
Definition
-neurons that RELEASE acetylcholine (in efferent division of peripheral nervous system)
Term
what are adrenergic fibers?
Definition
-neurons that RELEASE epinephrine & norephinephrine (in efferent division of peripheral nervous system)
Term
what is a cholinergic receptor?
Definition
-binds and responds to acetylcholine
-5 subclasses of cholinergic receptors exist
(in efferent division of peripheral nervous system)
Term
what are the 5 subclasses of cholinergic receptors?
Definition
-2 are nicotinic (N1 & N2)
-3 are muscarinic (M1, M2, M3)
Term
what is an adrenergic receptor?
Definition
-binds and responds to epinephrine and norepinephrine
-4 subclasses exist
Term
what are the 4 subclasses of an adrenergic receptor?
Definition
-2 are alpha1 & alpha2
-2 are beta1 & beta2
Term
what is represented by beta/alpha? M/N?
Definition

-beta/alpha = subclasses of cholinergic receptors

-M/N = subclasses of adrenergic receptors

Term
what is a preganglionic fiber?
Definition
-neuron whose cell body (soma) lies in the central nervous system (either in the brain or spinal cord)
-these fibers (neurons) release a neurotransmitter that travels across the neuro-neuronal synapse & binds to a second neuron
Term
what cell body (soma) lies in the central nervous system? what part of the central nervous system?
Definition
-preganglionic fiber
-either the spinal cord or brain
Term
what do preganglionic fibers release? where do they go?
Definition
-neurotransmitter
-they travels across the neuro-neuronal synapse
Term
what is the neuro-neronal synapse concerning the preganglionic fiber?
Definition
-preganglionic fibers release a neurotransmitter that travels across this and binds to a second neuron (postganglionic fibers)
Term
what is a postganglionic fiber?
Definition
-neuron whose cell body lies in the peripheral nervous system
-fiber binds to neurotransmitter that is released from preganglionic fiber
-axon extends to the effector organ & the released neurotransmitter binds to receptors on the effector organ
Term
what are the further divisions of the autonomic nervous system?
Definition
-sympathetic & parasympathetic
Term
where do the axons extend in the postganglionic fiber?
Definition
-effector organ (and released neurotransmitter binds to receptors on the effector organ)
Term
are viscera innervated by parasympathetic or sympathetic divisions? what is this referred to as?
Definition
-mostly both
-dual innervation
Term
what is dual innervation?
Definition
-when viscera is innervated by both parasympathetic/sympathetic divisions
Term
what is autonomic tone?
Definition
-the parasympathetic and sympathetic divisions oppose each other in action, and both are active all the time
-one division is usually exhibiting more tone than the other, depending on what the body needs
Term
what does the sympathetic division prepare the body for?
Definition
-"fight or flight"
-prepares body to cope with energetic or stressful situations
-uses ATP
ex: increases heart rate, increases blood pressure, decreases digestive functions
Term
what does the parasympathetic division govern?
Definition
-"rest and digest"
-controls vegetative or maintanence activities
-conserves ATP
-ex: decreases heart rate, decreases blood pressure, increases digestive functions
Term
where does the preganglionic neuron have an origin?
Definition
-in different sites in the sympathetic and parasympathetic division
Term
where is the origin site for the preganglionic neuron in the sympathetic division?
Definition
-thoracic lumbar region of the spinal cord (T1-L2)
-these are spinal nerves
Term
what is important about the thoracic lumbar spinal nerves? (T1-L2)
Definition
-it is the origin site of the preganglionic neuron in the sympathetic division
Term
where is the origin site for preganglionic neuron in the parasympathetic division?
Definition
-the brain and sacral region of the spinal cord
-these are cranial nerves and spinal nerves
Term
what nerves house the preganglionic neuron in the parasympathetic division?
Definition
-cranial nerves and spinal nerves (brain and sacral region of spinal cord)
Term
what are examples of cranial nerves?
Definition
-oculomotor nerve (III)
-facial nerve (VII)
-glossopharyngeal nerve (IX)
-vagus nerve (X)
Term
what is the cranial nerve #3 & what does it innervate?
Definition
-oculomotor nerve
- innervates (supplies) the smooth muscle of the eye that influences pupil
Term
what is cranial nerve VII? what does it innervate?
Definition
-facial nerve
innervates:
-nasal glands
-lacrimal glands of the eyes
-sublingual and submandibular salivary glands
Term
what is cranial nerve IX? what does it innervate?
Definition
-glossopharyngeal nerve
innervates:
-paratoid salivary glands
Term
what is cranial nerve X? what does it innervate?
Definition
-vagus nerve
-branches into 4 plexuses:
1) cardiac plexus: innervates heart
2) pulmonary plexus: innervates the lungs and the bronchi
3) esophageal plexus: innervates the esophagus
4) descending aortic plexus: innervates most of the abdominal viscera
Term
what percent of the parasympathetic supply is controlled by the vagus cranial nerve?
Definition
-90%
Term
what does the sacral region of the spinal cord innervate?
Definition
-the distal half of the large intestine
-the urinary bladder
-the reproductive organs
Term
what origin is different in the sympathetic and parasympathetic divisions?
Definition
-the origin of the ganglia (cell body of the postganglionic fiber
Term
where is the origins of the ganglia in the sympathetic division? what is it called?
Definition
-close to the spinal cord
-"sympathetic ganglion chain"
Term
what is the collateral ganglion?
Definition
-between the spinal cord and effector organ
-in the sympathetic division
Term
where do some preganglionic fibers synapse? what do these fibers release? what does this release cause? what does this initiate?
Definition
-synapses on adrenal medulla
-release acetylcholine (which binds to N1 receptors on the adrenal medulla)
-causes release of epinephrine and norepinephrine from the medullary tissue into the blood stream
-initiates a "system wide sympathetic response"
Term
what is system wide sympathetic response?
Definition
-initiated by the release of epinephrine and norepinephrine from the medullary tissue into the blood stream
Term
where is the origin of the ganglia in the parasympathetic division? what is another name for this?
Definition
-close to or in the effector organ
-"terminal ganglion"
Term
what is the terminal ganglion?
Definition
-origin of the ganglia is close to or in the effector organ in the parasympathetic division
Term
what are the 2 types of cholinergic receptors?
Definition
- nicotinic and muscarinic
Term
what happens in nicotinic cholinergic receptors?
Definition
-receptor stimulation by Ach ALWAYS results in an excitatory response of the effector cell
-the N2 receptor is on the sarcolemma of skeletal muscle cells and is used during depolarization
-the N2 recepor is ALL postganglionic cell bodies (all ganglia) on the adrenal medulla and is used for neurotransmitter release
Term
when does receptor stimulation always result in an excitatory response of the effector cell?
Definition
-in nicotinic cholinergic receptors
Term
where is the N2 receptor in nicotinic cholinergic receptors? when is it used?
Definition
-on the sarcolemma of skeletal muscle cells
-used during depolarization
-the N2 receptor is on all postganglionic cell bodies on the adrenal medulla
Term
what is used for neurotransmitter release in nicotinic cholinergic receptors?
Definition
-N2 receptor
Term
what happens in muscarinic cholinergic receptors?
Definition
-receptor stimulation by Ach CAN result in an excitatory or inhibitory response (response depends on the receptor type)
-M1 receptor is located on neural tissue & is excitatory
-M2 receptor is located on the heart & is inhibitory
-it decreases cardiac contractility & also decreases heart rate
-M3 is located on smooth muscle & glands & is excitatory
-increases muscle contraction & increases glandular secretions
Term
where is the M1 receptor in muscarinic cholinergic receptors? is it excitatory or inhibitory?
Definition
-on neural tissue (excitatory)
Term
where is the M2 receptor located in muscarinic cholinergic receptors?
Definition
-on the heart & is inhibitory
Term
what does the M2 decrease?
Definition
-cardiac contractility & heart rate
Term
where is the M3 receptor is located in muscarinic cholinergic receptors? excitatory or inhibitory?
Definition
-smooth muscle and glands (excitatory)
Term
what does M3 increase?
Definition
-muscle contraction & increases glandular secretions
Term
-what are the 2 types adrenergic receptors?
Definition
-alpha and beta
Term
what are the alpha receptors?
Definition
-stimulation by epinephrine and/or norepinephrine generally results in excitatory response like muscle contraction & increase glandular secretions
-exception: the alpha2 receptors on the gut muscles are INHIBITORY
Term
-what is the exception alpha2 receptors (from adrenergic receptors) ?
Definition
-the aplha2 receptors on the gut muscles are in inhibitory
Term
what are the beta receptors? what is the response? exception?
Definition
-beta1 & beta2
-stimulation by epinephrine and/or norepinephrine generally results in an inhibitory response
-exception: beta1 receptors on the heart are excitatory