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58 Cards in this Set
- Front
- Back
subdivisions of the ANS
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1) Sympathetic Nervous System
2) Parasympathetic Nervous System |
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What is the ANS?
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system of motor neurons that innervate the smooth muscle, cardiac muscle and glands of the body
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The ANS regulates
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visceral functions:
1) heart rate 2) Blood Pressure 3) digestion 4) urination |
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where does the brain stem become the spinal cord?
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at the foramen magnum
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the ANS can also be called the...
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general visceral motor division of the peripheral nervous system
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motor unit of the ANS
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A chain of TWO neurons:
1) preganglionic neuron 2) postganglionic neuron |
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preganglionic neuron
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- first neuron in the chain
- cell body of this neuron lies in the CNS -synapses with the 2nd neuron - Neuron 1 is ALWAYS MYELINATED |
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postganglionic neuron
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- extends to the visceral organs
- cell body in a peripheral ganglion - Neuron 2 is always NONMYELINATED -projects axon to an effector |
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autonomic ganglia
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motor ganglia containing motor neurons
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sympathetic division
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responsible for fight or flight
innervates smooth muscle in the walls of blood vessels |
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vasoconstriction
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narrowing of blood vessels, normally through the contraction of smooth muscle cells in the vessel walls
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sympathetic division is also known as
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thoracolumbar division
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Why can the Sympathetic division of the ANS be called the thoracolumbar division?
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the fibers emerge from the thoracic and superior lumbar parts of the spinal cord gray horns
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Why can the Parasympathetic division of the ANS be called the craniosacral division?
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its fibers emerge from the brain and the sacral spinal cord
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parasympathetic division is also called
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Craniosacral division
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Postganglionic (neuron 2) of the sympathetic division releases what neurotransmitter (usually)
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norepinephrine
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Postganglionic (neuron 2) of the parasympathetic division releases what neurotransmitter (usually)
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Acetylcholine (ACh)
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craniosacral outflow
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cell bodies of preganglionic (neuron 1) are in the brain stem or sacral region of the spinal cord gray horns
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Synapsing in the Parasympathetic Division occur
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IN or NEAR target organs
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General Functions of the Parasympathetic Division
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"Rest and Repose"
1) excitatory of digestive organs 2) depresses heart rate and blood pressure 3) constrict pupils of the eyes 4) sexual arousal 5) slows breathing 6) constricts urinary bladder |
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Both Neurons of the Parasympathetic Division release what neurotransmitter?
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Acetylcholine (Ach)
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receptor
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peripheral nerve ending that responds to particular types of stimuli
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Nicotinic Receptor
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excitatory effects
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muscarinic receptor
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either excitatory or inhibitory
longer lasting effects |
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Neuron 1 in Parasympathetic division
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- are long
- come from the brain stem or sacral spinal cord - produce ACh |
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Neuron 2 in Parasympathetic division
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- are short
- produce ACh - can be either excitatory or inhibitory |
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dual innervation
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each organ receives innervation from both sympathetic fibers and parasympathetic fibers,which modulate its activity
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visceral reflexes
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simplest functional units of the ANS, ALWAYS POLYSYNAPTIC
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polysynaptic
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one or more interneurons connect afferent (sensory) and efferent (motor) signals.
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monosynaptic
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consists of only two neurons
refers to the presence of a single chemical synapse |
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higher levels of autonomic control
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hypothalamus
medulla cerebral control |
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hypothalamus control
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tends to oversee and control certain ANS functions
main integration center |
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medulla control
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controls such things as respiratory breathing rhythms and timing, blood pressure and heart rate
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cerebral control
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allows us to consciously override some effects
ie: calming ourselves when fearful |
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chain ganglia (paravertebral chain)
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neuron 1 fibers are carried in the paravertebral chain which extends on either side of the vertebral column from C3-S4
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gray and white branches
(sympathetic chain) |
rami communicates
connect thoracic and lumbar spinal nerves to the chain |
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anatomy of the sympathetic chain
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1) gray and white branches
2) sympathetic neuron #1 3) gray ramus communicans |
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sympathetic neuron #1
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connects with the chain by the white ramus communicans.
WHITE MUST BE #1 GRAY MUST BE #2 |
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gray ramus communican
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carries neuron 2 out of the chain in a spinal nerve to its destination
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collateral ganglia (paravertebral)
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neuron #1 may pass through the chain without synapsing to one of the collateral ganglia
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collateral ganglia (paravertebral)
name the 3 |
1) celiac ganglion
2) superior mesenteric ganglion 3) inferior mesenteric ganglion |
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celiac ganglion
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innervates the stomach, liver, spleen, gallbladder
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superior mesenteric ganglion
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innervates small intestine and part of the colon
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inferior mesenteric ganglion
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innervates the kidneys, colon, sex organs
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adrenal medulla
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terminus for neuron 1
stimulates adrenal medulla to produce epinephrine, which are released into the blood stream |
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Neuron 1 of the Sympathetic division produces which neurotransmitter?
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acetylcholine (ACH)
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Neuron 2 of the Sympathetic division produces which neurotransmitter?
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norepinephrine (NE)
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membrane receptors of the sympathetic division
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1) andrenergic receptors
2) cholinergic receptors |
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andrenergic receptors
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responds to NE
broken down into Alpha and Beta Receptors |
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Alpha Receptors
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an andrengeric receptor
targets smooth muscle: constricts sphincters and blood vessels |
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beta receptors
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an andrengeric receptor
targets skeletal and smooth muscle: increases metabolic rate, usually excitatory |
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cholinergic receptors
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respond to ACh
affects sweat glands relaxes blood vessels in skeletal muscle |
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Neuron 1 in sympathetic division
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- releases ACh
- is short |
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Neuron 2 in sympathetic division
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- releases NE
- is long |
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Synapsing in Sympathetic Division
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occurs in prevertebral chain ganglia or paravertebral collateral ganglia
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Function of the Sympathetic Division
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prepares the body to cope with danger or excitement, the fight or flight division
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Neuron #1
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preganglionic or presynaptic
myelinated |
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Neuron #2
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postganglionic or postsynaptic
nonmyelinated |