Lecture 3 - Peripheral Nervous System Flashcards
What are the 2 types of sensory information? How to differentiate them?
- Somatic = Conscious: pain, proprioception, etc => can be pinpointed to an exact location
- Visceral = Unconscious: coming from viscera/glands => cannot be pinpointed
Which innervates more tissues: sympathetic or parasympathetic?
Sympathetic
List the 5 segments of the spinal cord from superior to inferior.
- Cervical
- Thoracic
- Lumbar
- Sacral
- Coccigeal
Describe the organization of the spinal nerves.
Rootlets => dorsal/ventral roots => spinal nerves => dorsal/ventral rami
What is a ganglia?
Collection of cell bodies in the PNS
What kind of neurons are sensory neurons?
Pseudounipolar
What kind of information does a spinal nerve carry? What do we call this?
Both motor and sensory = mixed nerve
What do the posterior rami supply?
Back intrinsic muscles and skin covering them
What do the anterior rami supply?
Limbs and ventral portion of the body
How many neurons from spinal cord involved in somatic motor innervation?
Single one connecting spinal cord to skeletal muscle
How many neurons from spinal cord involved in visceral motor innervation? What is the exception?
2: preganglionic and postganglionic neurons which synapse at ganglia
Exception: adrenal medulla composed of modified postganglionic neurons and innervated by preganglionic thoracic splanchnic sympathetic neurons
What are the 3 autonomic ganglia of the PNS?
- Paravertebral (chain) ganglia
- Prevertebral ganglia
- Intramural ganglia
Parasympathetic NS: how does the length of the preganglionic neuron compare to the postganglionic neuron? Why?
Longer preganglionic neuron because intramural ganglia are in the walls of the target organs
Sympathetic NS: how does the length of the preganglionic neuron compare to the postganglionic neuron? Why?
Longer postganglionic neuron because paravertebral and prevertebral ganglia are close to spinal cord
Where do the sympathetic preganglionic neurons synapse along the spinal cord? What do we call this?
T1 to L2 spinal segments = thoracolumbar outflow
Where do the parasympathetic preganglionic neurons synapse along the spinal cord? What do we call this?
- Brainstem cranial nerve nuclei (III, VII, IX, X)
- S2 to S4 spinal segments (sacral spinal cord)
Craniosacral outflow
Sympathetic outflow: if neurons only exit at T1-L2, how do we get
sympathetic signals to the top and the bottom of the body?
Along the length of sympathetic outflow (and through the WHOLE spinal column) we have sympathetic chain ganglia (paravertebral ganglia) where many of the sympathetic preganglionic fibers can move (up or down) to various sympathetic chain ganglia all along the length of the spinal cord and will form synapses with postganglionic fibers
How will the regions that can’t be innervated by the Vagus nerve be parasympathetically innervated? What are these 2 regions?
Parasympathetic splanchnic nerves in the sacral spinal cord (S2-S4)
Hindgut and pelvis
Sympathetic stimulation on heart?
- Increased heart rate
2. Increase in force of contraction
Sympathetic stimulation on blood vessels?
Constriction
Sympathetic stimulation on lungs?
Bronchodilation
Sympathetic stimulation on GIT?
- Decreased motility
- Sphincter contraction
- Decreased secretions
Sympathetic stimulation on bladder?
Inhibits urination
Sympathetic stimulation on penis?
Ejaculation