Divisions of ANS, somatic vs autonomic NS LO1-3

Question 1

Dual innervation

Answer 1

• ANS divisions can work independently or together
• Divisions generally have opposing effects
• One division dominates in specific circumstances
• Divisions counterbalance to control organ function
  and maintain homeostasis

Question 2

Sympathetic
function

Answer 2

Prepares the body for
heightened activity FFF
- heart (increase rate, BP)
- BV (dilate in cardiac and skeletal muscle)
- lung (dilate)
- liver (glucose release)
- sweat glands (sweat)
- stomach (decrease)
- intensive (decrease)
- adrenal gland (adrenaline, noradrenaline)
- kidney (reduce BF)
- eye (dilate)

Question 3

Parasympathetic function

Answer 3

rest and digest
- heart (decrease rate, BP)
- lung (constrict)
- stomach (increase)
- intensive (increase)
- kidney (increase BF)
- eye (constrict)

Question 4

Somatic vs autonomic nervous systems

Answer 4

Both are efferent divisions that distribute motor commands
* Differ in:
1. Neural (efferent) pathways (i.e. from CNS to effector)
2. Effectors (target organs)
3. Organ response
4. Neurotransmitters (NT)

Question 5

Somatic NS system overview

Answer 5

Control centre: Primary motor cortex (input from cerebellum and basal nuclei
Central neurons: Upper motor neurons
Peripheral motor neurons: Lower motor neuron
Target: skeletal muscle
Function: voluntary movement, somatic reflex

Question 6

Autonomic nervous system overview

Answer 6

Control centre: Hypothalamus (input from limbic system and cerebrum)
Central neurons: CNS interneurons
Peripheral motor neurons: Preganglionic, postganglionic neurons
Target: Cardiac muscle, Smooth muscle, Glands
Function: involuntary control of visceral organ function, glandular activity, visceral reflexes

Question 7

Peripheral motor neurons somatic

Answer 7

Somatic NS: Lower motor neuron cell body in either:
1. spinal cord motor nucleus (anterior grey horn), axon
exits CNS via ventral root of spinal nerve, OR
2. brainstem nucleus, axons exit CNS via cranial nerve

Question 8

Peripheral motor neurons autonomic

Answer 8

Autonomic NS: Preganglionic neuron cell body in either:
1. motor nucleus (lateral grey horn/matter), axon exits CNS via ventral
root of spinal nerve OR
2. brainstem nucleus, axons
exits CNS via cranial nerve

Question 9

Peripheral motor neurons neurotransmitters

Answer 9

First: always ACh released by preganglionic neuron
(excitatory)
Somatic: ACh released by
LMN (excitatory)
Autonomic: ACh OR NA
released by postganglionic
neuron (excitatory/inhibitory)

Question 10

Parasympathetic division pathway

Answer 10

Aka craniosacral
- Ganglia located close to,
or within, the target organ
- Preganglionic axon = long
- Postganglionic axon = short
- innervate: Pelvic organs, Distal portion of large intestine

Question 11

Sympathetic division pathway

Answer 11

aka thoracolumbar
- Ganglia located close to
spinal cord
- Preganglionic axon = short
- Postganglionic axon = long