Autonomic Nervous System Flashcards
(36 cards)
Efferent signals of the ANS can originate from four places. What are they?
- Spinal level - exits the ventral side
- Medulla oblongata - BP control
- Hypothalamus - integration center for entire ANS
- Thalamus and cortex - higher centers
The parasympathetic nervous system is also called the _____________________.
craniosacral division
Where are the cell bodies of the PNS preganglionic neurons located?
- Midbrain - cranial nerve 3
- Medulla oblongata - cranial nerves 7, 9, 10
- Sacral region of spinal cord
Are preganglionic neurons of the PNS long, or short?
Long
Are preganglionic neurons of the SNS long, or short?
Short
Where are the cell bodies of the SNS preganglionic neurons located? Where do they exit?
In the interomediolateral columns of the spinal cord. Exit at T1 through L3
The sympathetic nervous system is also called the __________________.
thoracolumbar system
Where are sympathetic ganglia located and what are the names for these ganglia?
Located near each side of the spinal cord and run the entire length of the spine from c-spine to the sacral level. Called the sympathetic trunks, or chain ganglia.
What enables the widespread effects of sympathetic pre-ganglionic signals?
Preganglionic sympathetic fibers synapse with several hundred post-ganglionic fibers in the sympathetic trunk/chain ganglia.
What are the collateral ganglia?
Sympathetic ganglia located in the abdominal cavity that controls the GI and urinary systems.
_________ cells in the adrenal medulla have phenylethanolamine N-methyl transferase acivity and therefore release 80% epinephrine and 20% norepinephrine.
Chromaffin
Which neurotransmitter is used by preganglionic neurons of both the SNS and PNS? What receptor type is found at the ganglionic synapse?
Ach - nicotinic receptor
Are nicotinic Ach receptors ionotropic or metabotropic? What subtype is found at neuromuscular junctions? What subtype is found at autonomic nervous system ganglia?
Nicotonic receptors are ionotropic and muscarinic are metabotropic.
N1 found at neuromuscular junctions.
N2 found at ANS ganglia (both PNS and SNS).
What receptor type is found at postganglionic parasympathetic nerves (at the end organ)? Are these ionotropic or metabotropic?
Ach - muscarinic. They are metabotropic.
Name the five subtypes of the adrendergic receptors and where they are found.
- B1 - heart
- B2 - lungs
- B3 - fat cells
- a1 - smooth muscle and blood vessels
- a2 - brain
Are adrenergic receptors ionotropic or metabotropic?
Metabotropic
What is responsible for a biphasic excitatory postsynaptic potential?
Post-ganglionic neuron expression of both muscarinic and N2 receptors. N2 binding –> fast response, muscarinic binding –> slow response.
What is co-transmission?
When non-cholinergic, non-adrenergic neurotransmitters are co-released with NE/Epi/Ach. Examples include ATP, neuropeptide Y.
Describe the triphasic contractile response of smooth muscle in response to co-transmission.
Phase 1: ATP - purinergic receptor binding is ionotropic –> rapid Ca2+ influx and depolarization.
Phase 2: NE - a1 binding causes G-protein and phospholipase C activation –> IP3 release –> Ca2+ release from the ER.
Phase 3: Neuropeptide Y - Y1 receptor binding –> prolonged increase in [Ca2+].
How is Ach inactivated? How are catecholamines inactivated?
Ach degraded by Achesterase.
Catecholamines are taken back by preganglionic neuron (reuptake - active transport) and broken down by MAO or COMT (catechol-O-methyl transferase).
What are the two mechanisms for the complimentary actions of the PNS and SNS?
- Opposing smooth muscles innervated separately by the PNS or SNS.
- Cells that have receptors for both PNS and SNS neurotransmitters.
visceral afferents
blood pressure, distension of the bladder
somatic afferents
surface sensations; pressure and pain
neural system within the GI
enteric
