Flashcards in ANS and Homeostasis, Ch 14 Deck (33):
What do autonomic motor neurons innervate?
Smooth muscle cells, cardiac muscle cells, glands, and produce involuntary actions.
What two neurons are involved during ANS innervation?
Preganglionic neuron, the initial efferent neuron whose cell body resides in the CNS, synapses on the
Postganglionic neuron, the cell body of a second neuron which triggers a change by releasing neurotransmitters.
In the SNS the preganglionic axons are often what, while the pstganglionic are often what? The opposite is generally true in axons of the PNS.
Where do the cell bodies of the preganglionic sympathetic neurons originate? What is the sympathetic nervous system called for this reason?
Thoracic and upper lumbar spinal cord
The ganglia are typically located near the spinal cord, and innervate their target cells.
The division of the ANS responsible for preparing the body for emergency situations, maintaining homeostasis during physical work, and mediating the body's visceral response to emotion.
Sympathetic nervous system
Where are the cell bodies of the preganglionic parasympathetic neurons located?
What is the parasympathetic system called because of this?
Within the nuclei of several cranial nerves in the brainstem and in the sacral region of the spinal cord.
The ganglia are typically located near or within the target organs.
What do the cranial nerves of the parasympathetic innervate?
Structures of the head and neck, the thoracic viscera, and most of the abdominal viscera.
Structures within the pelvic cavity.
The division of the ANS responsible for digestion and maintaining the body's homeostasis when at rest
Parasympathetic nervous system
Most of the cell bodies of the postganglionic neurons, that are found along the vertebral column. Extends beyond the thoracic and lumbar spinal cord, from the superior cervical ganglion down to the inferior sacral ganglion.
Sympathetic chain ganglia
Preganglionic neurons of the sympathetic originate where? Where do their axons go?
In the lateral horns of the thoracic and lumbar spinal cord.
The axons exit the spinal cord with the axons of lower motor neurons via the anterior root.
After exiting the anterior root, axons of preganglionic sympathetic neurons travel with the spinal nerve and the anterior ramus before branching off to form small nerves called what?
White rami communicantes
White because they're myelinated
What do axons enter after going through the white rami communicantes? It houses the cell bodies of postganglionic sympathetic neurons
Sympathetic chain ganglia
Some preganglionic neurons pass through the symp. chain ganglia without synapsing. Instead they may synapse on cell bodies in different chain ganglia, which are located near the target organ.
Many are located near the aorta, and are called preaortic ganglia
The preganglionic axons that synapse on the collateral ganglia located near the organs of the abdominopelvic cavity are part of the nerves called what?
Examples of the ganglia?
Superior mesenteric ganglion
Inferior mesenteric ganglion
A preganglionic nerve may synapse with a postganglionic neuron in what three ways?
Axon synapses with postganglionic neuron in sympathetic chain ganglion- gray rami communicantes
Descends or ascends and synapses with a postganglionic neuron in a different chain ganglion- gray rami communicantes
Passes through the chain ganglion and synapses with a postganglionic neuron in a collateral ganglion- travel to target cells directly
Small postganglionic neurons that exit the ganglia, rejoining and traveling with spinal nerves to reach their target cells.
Gray rami communicantes
Interacts with a target cell by binding to a protein-based receptor specially for it, which is embedded in the plasma membrane of the target cell.
The sympathetic preganglionic axon communicates the postganglionic by way of an excitatory synapse using what neurotransmitter?
Those receptors that bind to it are called what?
At the synapses with their target cells, postganglionic axons release one of what three neurotransmitters?
About 80% release norepinephrine.
What neurotransmitter receptors bind to norepinephrine or epinephrine?
On cardiac cells, the sympathetic nervous system increases heart rate and blood pressure. How does this happen?
Norepinephrine binds to B1 receptors on the cells, opening ion channels that raise the rate and force of contractions. Heightens blood delivered to tissues.
What are the effects of the sympathetic nervous system's norepinephrine on smooth muscle cells?
Constriction of blood vessels serving the digestive, urinary, and integumentary systems, serving most exocrine glands
Dilation of bronchioles, blood vessels serving the skeletal and cardiac muscles, pupils
Contraction of urinary and digestive sphincters
Relaxation of smooth muscle of the digestive tract
Cranial and sacral nerves involved in the parasympathetic, carrying nerve fibers, are what?
Oculomotor, facial, glossopharyngeal, vagus
Sacral nerves make up the pelvic nerves
Ganglia of the parasympathetic, typically found near the postganglionic neuron's target cells.
The main parasympathetic nerves that innervate most thoracic and abdominal viscera, and together provide about 90% of the parasympathetic innervation of the body.
Two vagus nerves, CN X
Branches contribute to several groups of plexuses that innervate specific organs.
Synapse on terminal ganglia in the walls of the viscera being innervated.
The preganglionic parasympathetic neurons of the oculomotor nerves synapse on terminal ganglia called what?
Several terminal ganglia, including these, house the cell bodies of sensory neurons and are the sites where preganglionic parasympathetic of the facial synapse on the postganglionic.
The preganglionic parasympathetic neurons of the glossopharyngeal synapse on postganglionic in small terminal ganglia called?
Branches from the sacral spinal cord form this, which in turn form plexuses on the pelvic floor. Some preganglionic neurons synapse in terminal ganglia in the plexuses.
Pelvic sphlanchnic nerves
Both the preganglionic and postganglionic parasympathetic neurons release this neurotransmitter at their synapses, and the effect is generally what?
Two main types of cholinergic receptors. One type is found on sweat glands in the skin and the membranes of all parasympathetic target cells. The other is located in the membranes of all postganglionic neurons within the sympathetic and parasympathetic ganglia as well as the adrenal medulla.
The parasympathetic nervous system decreases heart rate and blood pressure how?
Preganglionic parasympathetic neurons travel to the heart via the vagus nerve and stimulate postganglionic neuron to reduce the heart's rate of contraction, lowering blood pressure