human anatomy the autonomic nervous system ans. regulates various physiological processes...
TRANSCRIPT
Human Anatomy
The Autonomic Nervous System
ANS
ANS
• Regulates various physiological processes unconsciously, for instance:
1. Cardiovascular
2. Respiration
3. Digestion
4. Body temperature
5. Excretion
2 Subdivisions of the ANS
1. Sympathetic NS
• “fight or flight”
2. Parasympathetic NS
• “rest and repose”
Anatomy of ANS
• Consists of only 2 neurons1. Preganglionic neuron (#1)2. Ganglionic neuron (#2)• The ganglion is a structure where • the axon of the preganglionic neuron synapses
(release of neurotransmitter) with • the ganglionic neuron (dendrite or cell body)• The axon of the ganglion synapses with the
target cell or organ.
Anatomy of the ANS
• Differences between sympathetic and parasympathetic are:
1. Location of preganglionic (#1) cell body
2. Location of the ganglia
3. Neurotransmitters released at synapses
4. Effects on target organs
Sympathetic Anatomy
• Once again, just 2 cells
• Preganglion (#1) cell body in gray matter of spinal cord ---- levels T1 – L2
• Thoracolumbar system
Sympathetic AnatomyThoraco-lumbar
Sympathetic Anatomy
• Synapse of preganglionic (#1) with ganglionic (#2) neurons happens in the ganglion
• 3 cervical ganglia
• 3 abdominal ganglia
• Neurotransmitter is acetylcholine (ACh)
Sympathetic AnatomyThoraco-lumbar
Sympathetic Ganglia
• Paravertebral ganglia1. Cervical• Superior• Middle• Inferior2. Abdominal• Celiac• Superior mesenteric• Inferior mesenteric
Sympathetic AnatomyThoraco-lumbar
Sympathetic Anatomy
• Ganglionic (#2) axons are relatively long
• Synapse at target cell or organ
• Neurotransmitter is norepinephrine (NE)
Sympathetic AnatomyThoraco-lumbar
Parasympathetic Anatomy
• Once again, just 2 cells
• Preganglionic (#1) cell body in either:
1. Brainstem
2. Spinal cord ---- S2 – S4
• Craniosacral system
Parasympathetic Anatomy
Cranio-sacral
Parasympathetic Anatomy
• Synapse of preganglionic with ganglionic neurons happens in the ganglion
• Ganglia are located on the target organs
Parasympathetic Anatomy
Cranio-sacral
Parasympathetic Anatomy
• Ganglionic axons are relatively short
• Synapse at target cell or organ
• Neurotransmitter is acetylcholine (ACh)
Parasympathetic Anatomy
Cranio-sacral
Summary
FIGURE 17-2p. 445
Summary
• Sympathetic
1. Thoracolumbar
2. Paravertebral ganglia
3. ACh then NE
• Parasympathetic
1. Craniosacral
2. Ganglia at target
3. ACh and ACh
Biological Effects
• Most organs have dual innervation
1. CV
• S – increase heart rate, force of ventricle contraction, increase blood pressure by constricting smooth muscles of arteries
• P -- opposite
Biological Effects
2. Respiration• S – dilation of bronchiole smooth muscle
which increases diameter• P – opposite3. Digestion• S – decreases activity of organs and
glands• P -- opposite
Biological Effects
4. Vision
• S – dilation of pupil
• P – constriction of pupil
5. Reprodction
• S – causes ejaculation in males
• P – sexual arousal (erection) in both sexes