VETS2011 Lecture Notes - Lecture 15: Adrenal Medulla, Autonomic Nervous System, Sympathetic Nervous System
The Autonomic Nervous System
What is the ANS?
- Collection of peripheral afferent efferent neurones which link CNS with
visceral effector organs (not conscious control)
- Smooth muscle, cardiac muscle, mostly exocrine and some glands.
- Primary function: Internal Homeostasis
- Involuntary either using sympathetic or parasympathetic, very rapid.
Picture
Organisation of the efferent ANS
- Fight or flight, sympathetic:
- Preganglionic > Paravertebral ganglion > Postganglionic nerve > Target
organ
- 2 neuron efferent motor system connecting CNS to viscera
- Rest or digest, parasympathetic:
- Long preganglionic> Parasympathetic ganglia > Target organ
- 1 neuron efferent system connecting viscera to CNS.
Comparative anatomy of somatic and autonomic nervous system:
- Somatic only got one synapse.
- Autonomic got two: Pre to post ganglionic, and post ganglionic to target
organ.
- Autonomic: Post ganglionic nerves are unmyelinated.
Innervation of the adrenal medulla??
Dog park syndrome:
- Sympathetic nerves to organs
- But also adrenaline from adrenal medula.
Function of the adrenal medulla
- Release cocktail of adrenaline and noradrenaie into blood.
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Document Summary
Collection of peripheral afferent efferent neurones which link cns with visceral effector organs (not conscious control) Smooth muscle, cardiac muscle, mostly exocrine and some glands. Involuntary either using sympathetic or parasympathetic, very rapid. Preganglionic > paravertebral ganglion > postganglionic nerve > target organ. 2 neuron efferent motor system connecting cns to viscera. Long preganglionic> parasympathetic ganglia > target organ. 1 neuron efferent system connecting viscera to cns. Comparative anatomy of somatic and autonomic nervous system: Autonomic got two: pre to post ganglionic, and post ganglionic to target organ. Release cocktail of adrenaline and noradrenaie into blood. Adrenaline: increase in heart rate and metabolism. Noradrenaline: increase heart rate but less than adrenaline, inhibit git, causes pupil dilation and arterial pressure (by constricting, increases blood pressure. Secretes mixture into blood stream to adernegic receptors. Need acethycholine to get signal from pre to post ganglionic, then need adrenaline to bind to adnergenic receptors. Some postganglionic nerves (plexus) are sitting right inside the organ.
