1. PNS and the autonomic nervous system - differences between the somatic and the autonomic nervous system - differences between the Sympathicus and the Parasympathicus 2. Integration and control of the autonomic nervous system: Hypothalamus 3. Drive states Visceral reflexes and “drive states”: Autonomic nervous system
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Visceral reflexes and “drive states”: Autonomic nervous system · Nervus Vagus N. vagus (X. brain nerve) is the only brain nerve of the 12 cranial nerves that does not only innervate
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1. PNS and the autonomic nervous system
- differences between the somatic
and the autonomic nervous system
- differences between the Sympathicus
and the Parasympathicus
2. Integration and control of the autonomic nervous system:
Hypothalamus
3. Drive states
Visceral reflexes and “drive states”: Autonomic
nervous system
Regulation of energy consumption and homeostasis,
largely involuntary „visceral reflexes“
- Sympathicus: often increasing energy consumption,
preparation for action, „fight and flight“
- Parasympathicus: often decreasing energy consumption,
regeneration, „rest and digest“
Sometimes antagonistic action in the same organ (heart,
lung), sometimes only one system (bladder)
Differences between the
autonomic and the somatic
system
I. Different anatomy of the
autonomic nervous system:
Production of a fine network in the
target organs („Plexus“)
II. Different target innervation:
No specialized pre- or
postsynaptic region but
swellings (varicosities) where
neurotransmitters are
released and diffuse over
some distances
No point-to-point contacts
but more diffuse control
Differences between the autonomic and the somatic
system
III. Presence of axo-axonic synapses between sympathic,
parasympathic and sympathic-parasympathic fibers
Differences between the autonomic and the somatic
system
IV. Different position of the neurons:
Cell bodies of the motoneurons are located outside of the spinal
cord in the autonomous ganglia
Differences between the autonomic and the somatic
system
Preganglionic neuron in
the spinal cord (lateral
horn of the thoracic and
lumbar region),
postganglionic neuron in
the autonomous ganglia
Anatomical distinction
according to the origin of the
neurons
- Sympathicus: Mostly middle
portion of the spinal cord
(thoracic and lumbar region)
- Parasympathicus: Medulla
(brain stem) and sacral spinal
cord
Differences between the
Sympathicus and the
Parasympathicus
Main nerve of the parasympathicus:
Nervus Vagus
N. vagus (X. brain nerve) is the only
brain nerve of the 12 cranial
nerves that does not only
innervate parts of the head
region
Distinction according to the neurotransmitter of the
neurons; in both systems usually chain of 2 neurons