Autonomic nervous System

Peripheral Nervous system

• Somatic Nervous System

VS

• Autonomic Nervous System

Both a part of the Peripheral Nervous system:

Somatic Nervous System:

Responsible for conscious perception and the resulting voluntary response via the skeletal system (movement).

• General sensory neurons Skeletomotor neurons

Autonomic Nervous System:

Receives sensation from the visceral sense, and provides the involuntary response.

• Para/sympathetic motor neurons, visceral general sensory neurons

• e.g heartbeats, digestion, pupil dilation, etc.

Autonomic Nervous System function

• Sympathetic vs Parasympathetic nervous system

Sympathetic nervous system:

• Fight, flight or freeze

  • Stimulatory (sometimes)

• e.g pupil dilation: allows more light to enter & more vision

Parasympathetic nervous system

• Rest & digest

  • Inhibitory (sometimes)

• e.g pupil constriction: lets less light to enter & less vision

Pathway through nervous systemn

• Sympathetic nervous system

  • Synapse at the same level

  • Synapse at a higher or lower level

  • Synapse in a distant collateral ganglion

Thoracomlumbar outflow:

• Neurons only exit from the lateral horn of spinal segments

1. Sympathetic motor neurons originate from the lateral horns of T1-L2 spinal segments

2. Information travels to the sympathetic chain via the pre-ganglionic neuron

3. Pre-ganglionic neuron synapses with the post-ganglionic neuron  in the sympathetic ganglion which makes up the sympathetic chain via the ingate

4.  post-ganglionic neuron goes out to innervate viscera via the out gate

Pathway through nervous systemn

• Parasympathetic nervous system

Cranial & sacral divisions/outflow:

• Neurons only exit from the grey matter of spinal segments

1. Sympathetic motor neurons originate from the grey matter of T1-L2 spinal segments (not enough grey matter in sacral spine segments to form lateral horns)

2. Synapsing of pre-ganglionic neuron and post-ganglionic neuron occurs CLOSE to the visceral structures

3. Innervates visceral organs

4. Cranial divisions have synapsing occur close to the organs

5. Sacral divisions have preganglionic neurons exit from grey matter, synapsing close to true pelvic organs