10 - Autonomic Nervous System

Question 1

What does the ANS do

Answer 1

• Innervate smooth muscle, cardiac muscle & glands
• Make adjustments to ensure optimal support for body activities
• Operate via subconscious control

Question 2

PSNS role

Answer 2

• Promotes maintenance activities & conserves body energy
• Blood pressure, heart rate & respiratory rates are low
• GI tract activity is heavy
• Pupils are constricted & lenses are accommodated for close vision
• D Division - digestion, defecation & diuresis

Question 3

SNS role

Answer 3

• fight or flight
• Promotes adjustments during exercise or when threatened
• Blood flow is shunted to skeletal muscles & heart
• Bronchioles dilate
• Liver release glucose - energy
• Pupils dilate
• E division - exercise, excitement, emergency, embarrassment

Question 4

Where are preganglionic neurons for SNS?

Answer 4

• Preganglionic neurons in spinal cord segments T1-L2
• Sympathetic neurons produce spinal cord lateral horns

Question 5

Sympathetic trunk ganglia

Answer 5

• 23 sympathetic trunk ganglia
• NOTE: extend beyond level of T1-L2 -> sympathetic trunk is longer, allows innervation to head & pelvis

Question 6

Upon entering sympathetic trunk ganglion, a preganglionic fiber may do 1 of 3 things:

Answer 6

• Synapse at same level
• Synapse at a higher or lower level
• Synapse in a distant collateral ganglion anterior to vertebral column