L6 Autonomic nervous system

Question 1

Speed of ANS circuits

Answer 1

Slow

Question 2

Speed of somatic motor system

Answer 2

Rapid

Question 3

ANS circuits targets?

Answer 3

Widespread actions.
Wide coordinated and graded control i.e. when GIT is active, other visceral structures will cease to allow for this activity.
All tissue and organs except skeletal muscles.

Question 4

Describe targeting system of somatic motor system

Answer 4

Accurate.

Peripheral targets.

Question 5

Somatic motor system is?

Answer 5

Monosynaptic

Question 6

Describe list of effects of sympathetic nervous system

Answer 6

• Increased heart rate and blood pressure
• Depressed digestive function
• Mobilized glucose reserves
• Orgasm
• Micturition i.e. relaxation of the detrusor

Question 7

Describe list of effects of parasympathetic nervous system (i.e. vagus)

Answer 7

• Slower heart rate, fall in pressure
• Increased digestive functions
• Glucose storage in the liver
• Erection and lubrication
• Inhibition of micturition
• Stop sweating

Question 8

Describe sympathetic ganglia

Answer 8

• Short preganglionic fibres: found close to NS (brainsteam and spinal cord)
• Long postganglionic fibres

Question 9

Describe ganglia of parasympathetic nervous system

Answer 9

Long preganglionic fibres with ganglia at a distance to CNS often found flat to the organ being regulated.

Question 10

Sympathetic preganglionic nerves is located where?

Answer 10

Located on a restricted region of spinal cord between 1st thoracic spinal segment and 2/3 lumbar segment within the lateral horn of the spinal cord (between the dorsal and ventral horns)

Question 11

Where do motor sympathetic preganglionic fibres leave?

Answer 11

They leave through the ventral root to join the spinal nerve.

Question 12

What is the sympathetic trunk/chain?

Answer 12

Preganglionic nerves give rise to preganglionic fibres which travel in the ventral route, join the spinal nerve, and then as the spinal nerve passes by, they jump out to join the parallel system running adjacent to the spinal cord.

Question 13

Where does the sympathetic trunk run?

Answer 13

They run the entire length of vertebral column.

Question 14

Ganglia (paravertebral) are associated with all vertebral levels except for?

Answer 14

Cervical region (superior, middle, and inferior cervical ganglia)

Question 15

Ganglion impar?

Answer 15

These are terminal ganglia which joins the sympathetic chain together.

Question 16

T1-L2/3 local structure leaves the?

Answer 16

Leaves the intermediolateral nucleus (IML).

Question 17

T1-L2/3 local structure travels in?

Answer 17

Travels in ventral roots

Question 18

T1-L2/3 local structure joins the?

Answer 18

joins the spinal nerve

Question 19

T1-L2/3 local structure enters the?

Answer 19

Enters the sympathetic ganglion that is associated with that vertebral level.

Question 20

T1-L2/3 local structure synapses on?

Answer 20

Synapses on the sympathetic post-ganglionic neuron.

Question 21

After synapsing on sympathetic post-ganglionic neuron, T1-L2/3 local structure jumps back?

Answer 21

Jumps back into the spinal nerve.

Question 22

Where does T1-L2/3 local structure enter?

Answer 22

Enters dorsal or ventral primary rami.

Question 23

Describe pathway of above T1 and below L2/3 distant structure

Answer 23

• Leaves IML and travel in ventral roots.
• Joins spinal nerve
• Exits spinal nerve and enter sympathetic ganglion.
• Ascend or descend sympathetic chain then synapse on ganglion cell.
• Enters dorsal and ventral primary rami.

Question 24

Describe the first pathway of medial visceral nerves

Answer 24

• Leaves IML
• Travels in ventral roots
• Joins spinal nerve
• Enters sympathetic ganglion
• Doesn’t rejoin the spinal nerve after innervating sympathetic post-ganglionic ganglion.
• Instead it coalesces to form own nerve which penetrates towards heart.

Question 25

Which nerve innervates the heart?

Answer 25

Stellate and T2/T3

Question 26

Describe second pathway of medial visceral nerves

Answer 26

• Leaves IML
• Travels in ventral roots
• Joins spinal nerve
• Enter sympathetic ganglion
• Once in sympathetic chain, descend in chain
• Fuse with other postganglionic fibres
• Leave the chain and head towards prevertebral nuclei
• The preganglionic that leave the chain are called splanchnic nerves
• Post ganglionic fibres follow the blood vessels until it gets smaller to supply discrete region.
• Sympathetic fibres can regulate blood supply and organ itself so that if it’s active, you can control both at once.

Question 27

Medial visceral nerves include?

Answer 27

Greater, lesser and least splenetic thoracic nerves.

Question 28

Lumbar splenetic nerves emerge where?

Answer 28

Emerges medially to supply inferior and superior mesenteric ganglion.

Question 29

Parasympathetic nervous system originates from?

Answer 29

2 nuclei: 1st is dorsal motor nucleus of vagus in the medulla: regulates GIT

2nd is a nucleus called nucleus ambiguous: contains parasympathetic preganglionic fibres; travels to splenic flexure.

Question 30

Parasympathetic nervous system is regulated by which structures?

Answer 30

Medullary regions, midbrain structures, hypothalamus, amygdala, medial frontal cortex (where emotional regulation of behaviour happens)

Question 31

Which neurons are found in cardiopulmonary plexus?

Answer 31

Parasympathetic postganglionic neurons