Chr. 15 - The Autonomic Nervous System Flashcards
[15.1] What is the somatic nervous system?
The nervous system innervating skeletal muscles.
[15.1] What is the autonomic nervous system?
The part of the nervous system regulating cardiac muscle, smooth muscle, and glands.
[15.1] What is a visceral effector?
Any tissue of cardiac muscle, smooth muscle, or glands innervated by the ANS
[15.1] What is biofeedback?
Information of a body function displayed by monitoring devices.
[15.1] What are interoceptors?
Sensory receptors located in blood vessels, visceral organs, muscles, and the nervous system that monitor the internal environment.
[15.1] What are the branches of the autonomic nervous system?
The sympathetic, parasympathetic, and enteric.
[15.1] What is dual innervation?
An arrangement of innervation of organs by both sympathetic and parasympathetic branches of the autonomic nervous system.
[15.1] What is an autonomic ganglion?
A cluster of nerve bodies in the autonomic nervous system.
[15.1] Describe an autonomic nerve pathway.
Comprised of two neurons:
The first, known as the preganglionic neuron, originates in the CNS where the cell body is found, with a myelinated axon running down into an autonomic ganglion found in the PNS. Certain motor neurons can run to a chromaffin cell instead of a ganglion.
The second, known as the postganglionic neuron, originates in the ganglion and has an unmyelinated axon running from the ganglion to the effector.
[15.1] What is a chromaffin cell?
A specialized cell in the adrenal medullae innervated by a preganglionic nerve. Secrete epinephrine and norepinephrine.
[15.2] What is a preganglionic neuron?
A neuron with the cell body originating in the CNS and extending a myelinated axon to either an autonomic ganglion or a chromaffin cell.
[15.2] What is a postganglionic neuron?
A neuron with the cell body originating in the autonomic ganglion synapsing with one or more preganglionic neurons, and extending its unmyelinated axon to a visceral effector.
[15.2] What is the thoracolumbar division?
The preganglionic neurons of the sympathetic division with cell bodies originating in the lateral horns of the grey matter of T1-12 and L1/2.
[15.2] What is the thoracolumbar outflow?
Specifically the axons of the thoracolumbar division.
[15.2] What is the craniosacral division?
The preganglionic neurons of the parasympathetic division with cell bodies originating in cranial nerves III, VII, IX, X, as well as lateral grey matter of S2-4.
[15.2] What is the craniosacral outflow?
Axons of the craniosacral division.
[15.2] What are the groups of autonomic ganglia?
Sympathetic ganglia and parasympathetic ganglia.
[15.2] List and describe the types of sympathetic ganglia.
Sympathetic trunk ganglia, either side of the vertebral column that innervate organs above the diaphragm.
Prevertebral ganglia, found anterior to the vertebral column close to abdominal arteries and innervate organs below the diaphragm.
[15.2] What are terminal ganglia?
Ganglia of the parasympethic (or craniosacral) division. Located close to or within visceral organs.
[15.2] What are autonomic plexuses?
Sympathetic and parasympathetic neurons forming tangled networks typically lying along major arteries.
[15.2] List major plexuses and their location.
Cardiac plexus, thorax.
Pulmonary plexus, thorax.
Celiac plexus, abdomen.
Superior mesenteric plexus, abdomen.
Inferior mesenteric plexus, abdomen.
Hypogastric plexus, abdomen.
Renal plexus, abdomen.
[15.2] What is a white ramus?
A short pathway through which a myelinated preganglionic neuron of the sympathetic division passes through.
[15.2] What are the white rami communicantes?
The collective term for all white rami.
[15.2] How many sympathetic trunk ganglia are there in each section of the vertebral column?
3 cervical
11 or 12 thoracic
4 or 5 lumbar
4 or 5 sacral
1 coccygeal.
[15.2] What are the divisions of cervical ganglia and which regions do they innervate?
Superior cervical ganglia, innervate visceral effectors of the head and heart.
Middle cervical ganglion, innervate the heart and blood vessels of: the neck, shoulder, and upper limb.
Inferior cervical ganglion, innervate the heart and blood vessels of: the neck, shoulder, and upper limb.
[15.2] How do axons leave the sympathetic trunk?
Entering spinal nerves,
Form cephalic periarterial nerves,
Form sympathetic nerves,
Form splanchnic nerves.
[15.2] Describe how sympathetic postganglionic neurons enter spinal nerves.
Axons enter a pathway known as the grey ramus and merge with the anterior ramus of a spinal nerve.
[15.2] Describe how cephalic periarterial nerves are formed.
Postganglionic neurons leave the sympathetic ganglion of the trunk and extend into the head, following arteries and innervating visceral effectors.
[15.2] Describe how sympathetic nerves are formed.
By postganglionic axons leaving the sympathetic trunk and extending to their destination of innervation.
[15.2] Describe how splanchnic nerves are formed.
Sympathetic preganglionic axons pass through the sympathetic trunk without terminating within it. Once beyond, they are known as splanchnic nerves and synapse with sympathetic postganglionic neurons.
[15.2] What are the types of splanchnic nerves?
Splanchnic nerves that run to the abdominopelvic organs, and splanchnic nerves to run to the adrenal medulla.
[15.2] What is the difference between the types of splanchnic nerves?
Splanchnic nerves to the abdominopelvic organs synapse with postganglionic neurons before reaching the viscera.
Splanchnic nerves to the adrenal medulla do not synapse with postganglionic neurons; instead they run directly to chromaffin cells.
[15.2] Describe the structure of the parasympathetic division.
Cell bodies of parasympathetic neurons originate in two places: the brainstem, and exit as part of a cranial nerve; and in the grey matter of S2-4 of the spinal cord, exiting as part of the anterior root.
[15.2] What is the cranial parasympathetic outflow?
The axons of preganglionic neurons extending from the cranial nerves.
[15.2] What is the sacral parasympathetic outflow?
The axons of the preganglionic neurons extending from the grey matter of S2-4
[15.2] What are the ganglia within the cranial outflow?
Ciliary, pterygopalatine, submandibular, otic, and “ganglia associated with vagus X nerve.”
[15.2] Describe the ciliary ganglia.
Lie lateral to the optic III nerve, postganglionic axons innervate smooth muscle of the eye.
[15.2] Describe the pterygopalatine ganglia.
Located lateral to sphenopalatine foramen. Receive axons from facial VII nerve. Postganglionic axons innervate nasal mucosa, palate, pharynx, and lacrimal glands.
[15.2] Describe submandibular ganglia.
Located near ducts of submandibular salivary glands. Innervate submandibular and sublingual salivary glands.
[15.2] Describe the otic ganglia.
Located inferior to foramen ovale, receive from glossopharyngeal IX nerves and innervate parotid salivary glands.
[15.2] Describe ganglia associated with vagus X nerve.
Contain 80% of cranial outflow, extend to many terminal ganglia in thorax and abdomen. Innervates heart, airway, liver, gallbladder, stomach, pancreas, small intense, and a portion of large intestine.
[15.2] What are pelvic splanchnic nerves?
Preganglionic axons originating in the sacral spinal column and extending to form terminal ganglia. Postganglionic neurons innervate smooth muscle and glands of the colon, ureters, urinary bladder, and reproductive organs.
[15.3] What are the classifications of autonomic neurons based on neurotransmitters?
Cholinergic and adrenergic.
[15.3] What is a cholinergic neuron?
Neurons that release acetylcholine as a neurotransmitter.
[15.3] Which neurons within the ANS are cholinergic?
All preganglionic neurons, all parasympathetic postganglionic neurons, and most sympathetic postganglionic neurons innervating sweat glands.
[15.3] Which types of cholinergic receptors exist?
Nicotinic and muscarinic.
[15.3] Describe nicotinic receptors.
Receptors that bind acetylcholine but can be activated by nicotine. Present in plasma membranes of dendrites of both types of postganglionic neurons. Also found in chromaffin cells, and motor end plates of NMJs.
[15.3] Describe muscarinic receptors.
Receptors that bind acetylcholine as well as a poison known as muscarine. Present in plasma membranes of effectors and innervated by parasympathetic postganglionic axons.
[15.3] What is an adrenergic neuron?
Autonomic neurons that release norepinephrine.
[15.3] Describe adrenergic receptors.
Receptors that bind both norepinephrine and epinephrine.
[15.3] Which types of adrenergic receptors exist?
Alpha and beta receptors.
[15.3] Which enzymes inactivate norepinephrine?
Monoamine oxidase and catechol-0-methyltransferase.
[15.3] What is an agonist?
A substance that binds to and activates a receptor.
[15.3] What is an antagonist?
A substance that binds to and blocks a receptor.
[15.4] What is autonomic tone?
The balance between sympathetic and parasympathetic activity.
[15.4] Describe the fight-or-flight response.
A stimulation of the sympathetic division and inhibition of the parasympathetic division.
[15.4] Describe the rest-and-digest response.
An activation of the parasympathetic division and inhibition of the sympathetic division.
[15.5] What is an autonomic reflex?
Responses that occur when a nerve impulse passes through an autonomic reflex arc.
[15.5] What region of the brain primarily directs the ANS?
The hypothalamus.
