Chapter 15 Autonomic Nervous System
sympathetic (thoracolumbar)
"fight or flight" division. the part of the autonomic nervous system that contains chiefly adrenergic fibers and tends to depress secretion, decrease the tone and contractility of smooth muscle, and increase heart rate — compare
parasympathetic division (craniosacral)
"rest and digest" division. The part of the involuntary nervous system that serves to slow the heart rate, increase intestinal and glandular activity, and relax the sphincter muscles.
rami communicantes
A nerve which connects other nerves. Gray rami communicantes connect thoracic sympathetic ganglia to adjacent spinal nerves. White rami communicantes carry preganglionic sympathetic fibers from the spinal nerves to the sympathetic ganglia.
autonomic reflexes
All reflexes that involve a response of a visceral effector which are cardiac muscles, smooth muscles and glands. They involve preganglionic and postganglionic efferent neurons.
excitatory
An effect of a substance adding to an action.
inhibitory
An effect of a substance cancelling out, or partially cancelling out a action.
autonomic plexuses
Are formed from both sympathetic and parasympathetic fibers and innervate visceral organs to regulate overall activity.
involuntary
Meaning not mentally thought about, usually describing an immediate reaction.
visceral reflexes
Reflexes that are monitored and mediated by the autonomic nerves and begin in the viscera. They are muscular responses to stimulus in the organs.
terminal ganglia
a cluster of cell bodies of parasympathetic postganglionic neurons either lying very close to the visceral effectors or located within the walls of the visceral effectors supplied by the postganglionic neurons. Also called intramural ganglion.
autonomic ganglia
a cluster of cell bodies of sympathetic or parasympathetic neurons located outside the central nervous system.
sympathetic trunk ganglia
a cluster of cell bodies of sympathetic postganglionic neurons lateral to the vertebral column, close to the body of a vertebra. These ganglia extend inferiorly through the neck, thorax, and abdomen to the coccyx on both sides of the vertebral column and are connected to one another to form a chain on each side of the vertebral column. Also called vertebral chain ganglia or paravertebral ganglia.
acetylcholine
a compound that occurs throughout the nervous system, in which it functions as a neurotransmitter
adrenal medulla
adrenal medulla- Inner portion of adrenal gland. makes epinephrine and norepinephrine. Epinephrine is secreted in response to low blood levels of glucose,exercise and stress; it causes the breakdown of the storage product glycogen to the sugar glucose in the liver, facilitates the release of fatty acids from adipose tissue, causes dilation of the small arteries within muscle and increases the output of the heart. Norepinephrine secreted by the adrenal gland acts to narrow blood vessels and raise blood pressure.
baroreceptors
are receptors that monitor pressure, found in the carotid sinus it measures blood pressure.
autonomic tone
balance between sympathetic and parasympathetic activity which is regulated by the hypothalamus
beta (β) receptors
cell membrane receptors in the sympathetic nervous system, which dampen the response to catecholamines. They are divided into Beta-1, -2 and -3 receptors.
alpha (α) receptors
cell membrane receptors in the sympathetic nervous system, which evoke an excitatory response of smooth muscle cells to catecholamines.
cholinergic receptors
cell that responds to the neurotransmitter acetylcholine. These particular receptors are part of the autonomic nervous system.
nicotinic receptors
cells that respond to nicotine, a neurotransmitter. These cells function mainly in the autonomic nervous system of the body. Nicotinic receptors are a type of acetylcholine receptor (cholinergic receptor)
epinephrine
hormone secreted by the adrenal medulla that produces actions similar to those that result from sympathetic stimulation; aka "adrenaline"
norepinephrine
hormone secreted by the adrenal medulla that produces actions similar to those that result from sympathetic stimulation; aka "noradrenaline"
dual innervation
innervation from both sympathetic and parasympathetic neurons (dual=two), they inhibit and excite the same effector
interoceptors
interoceptors- sensory receptors located in blood vessels, visceral organs, muscles, and the nervous system that monitor internal environment conditions
splanchnic nerves
paired visceral nerves that carry fibers of the ANS as well as sensory fibers from organs.
chemoreceptors
sensory receptors that detect the presence of a specific chemical
muscarinic receptors
structures found in the membranes of some cells that are responsive to muscarine. Part of the parasympathetic nervous system. one of the main functions of Muscarinic receptors is in the regulation of heart rate These structures are part of the larger family cholinergic receptors.
preganglionic neurons
the first autonomic neuron in an autonomic pathway, with its cell body and dendrites in the brain or spinal cord and its myelinated axon ending at an autonomic ganglion, where it synapses with a postganglionic neuron.
autonomic nervous system
the part of the nervous system that controls the bodily functions not consciously directed. Breathing, the heartbeat, and digestive processes are all jobs of the autonomic nervous system.
postganglionic neurons
the second autonomic motor neuron in an autonomic pathway, having its cell body and dendrites located in an autonomic ganglion and its myelinated axon ending at cardiac muscle, smooth muscle, or gland.
adrenergic receptors
they are integral membrane proteins and can be found in plasma membrane in either postsynaptic neurons or effector cells.
