Autonomic Nervous System

Question 1

Efferent signals of the ANS can originate from four places. What are they?

Answer 1

1. Spinal level - exits the ventral side
2. Medulla oblongata - BP control
3. Hypothalamus - integration center for entire ANS
4. Thalamus and cortex - higher centers

Question 2

The parasympathetic nervous system is also called the _____________________.

Answer 2

craniosacral division

Question 3

Where are the cell bodies of the PNS preganglionic neurons located?

Answer 3

1. Midbrain - cranial nerve 3
2. Medulla oblongata - cranial nerves 7, 9, 10
3. Sacral region of spinal cord

Question 4

Are preganglionic neurons of the PNS long, or short?

Answer 4

Long

Question 5

Are preganglionic neurons of the SNS long, or short?

Answer 5

Short

Question 6

Where are the cell bodies of the SNS preganglionic neurons located? Where do they exit?

Answer 6

In the interomediolateral columns of the spinal cord. Exit at T1 through L3

Question 7

The sympathetic nervous system is also called the __________________.

Answer 7

thoracolumbar system

Question 8

Where are sympathetic ganglia located and what are the names for these ganglia?

Answer 8

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.

Question 9

What enables the widespread effects of sympathetic pre-ganglionic signals?

Answer 9

Preganglionic sympathetic fibers synapse with several hundred post-ganglionic fibers in the sympathetic trunk/chain ganglia.

Question 10

What are the collateral ganglia?

Answer 10

Sympathetic ganglia located in the abdominal cavity that controls the GI and urinary systems.

Question 11

_________ cells in the adrenal medulla have phenylethanolamine N-methyl transferase acivity and therefore release 80% epinephrine and 20% norepinephrine.

Answer 11

Chromaffin

Question 12

Which neurotransmitter is used by preganglionic neurons of both the SNS and PNS? What receptor type is found at the ganglionic synapse?

Answer 12

Ach - nicotinic receptor

Question 13

Are nicotinic Ach receptors ionotropic or metabotropic? What subtype is found at neuromuscular junctions? What subtype is found at autonomic nervous system ganglia?

Answer 13

Nicotonic receptors are ionotropic and muscarinic are metabotropic.

N1 found at neuromuscular junctions.

N2 found at ANS ganglia (both PNS and SNS).

Question 14

What receptor type is found at postganglionic parasympathetic nerves (at the end organ)? Are these ionotropic or metabotropic?

Answer 14

Ach - muscarinic. They are metabotropic.

Question 15

Name the five subtypes of the adrendergic receptors and where they are found.

Answer 15

1. B1 - heart
2. B2 - lungs
3. B3 - fat cells
4. a1 - smooth muscle and blood vessels
5. a2 - brain

Question 16

Are adrenergic receptors ionotropic or metabotropic?

Answer 16

Metabotropic

Question 17

What is responsible for a biphasic excitatory postsynaptic potential?

Answer 17

Post-ganglionic neuron expression of both muscarinic and N2 receptors. N2 binding –> fast response, muscarinic binding –> slow response.

Question 18

What is co-transmission?

Answer 18

When non-cholinergic, non-adrenergic neurotransmitters are co-released with NE/Epi/Ach. Examples include ATP, neuropeptide Y.

Question 19

Describe the triphasic contractile response of smooth muscle in response to co-transmission.

Answer 19

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+].

Question 20

How is Ach inactivated? How are catecholamines inactivated?

Answer 20

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).

Question 21

What are the two mechanisms for the complimentary actions of the PNS and SNS?

Answer 21

1. Opposing smooth muscles innervated separately by the PNS or SNS.
2. Cells that have receptors for both PNS and SNS neurotransmitters.