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Nervous system part 2
Terms in this set (11)
What are the main functions of the spinal cord and spinal nerves?
1. Pathway for sensory and motor impulses
2. Responsible for reflexes
What are some facts about the spinal cord?
31 pairs of spinal nerves, spinal cord meninges that encapsulate and protect the spinal cord, central canal has CSF within, anterior(ventral) roots contain motor axons, posterior(dorsal) roots contain sensory axons ((Dorsal root ganglion)), anterior and posterior root unite within the intervertebral foramen to become a spinal nerve
What do the lateral and anterior horns contain?
In the lateral horn there are cell bodies of automatic motor neurons, In the anterior horn there are cell bodies of somatic motor neurons(talks to skeletal muscle)
What is in the posterior horn?
axons of sensory neurons and cell bodies of interneurons
What is the gray commissure?
unmmyelinated axons that communicate between the right and left side
Define a reflex and reflex arc
A reflex is a rapid, involuntary automatic reaction of muscles or glands to a stimulus
A reflex arc is the neural wiring of a single reflex (Receptor in the PNS, communicates with the CNS and ends at a peripheral effector
What are some general characteristics of nervous system pathways?
Ascending- sensory information from PNS to CNS
Descending- Motor, initiated in the brain transmitted down the spinal cord
Deccussation-over 90% of pathways cross over eachother
Contralateral-Ends up on opposite side of where it started
Ipsilateral- same side
What's important about the pyramids?
Fibers descending from the cerebral cortex form a thick pair of thick anterior bulges in the medulla oblongata
Describe the difference between sympathetic and parasympathetic systems
Sympathetic- "Fight or flight" Arousal. Thoracic. Short pre-ganglionic neuron, long post-ganglionic neuron
Parasympathetic- "Rest and digest" Refueling the body. Ganglion usually near or in the wall of effector organ. When close to target--terminal ganglia, when in the wall of ogran--Intramural ganglia
Describe 3 possible ways a sympathetic fiber can travel
1. Paravertebral ganglia- Houses sympathetic ganglionic neuron cell bodies down spinal cord
2. Collateral ganglia a.Celiac b.Superior mesenteric c. inferior mesenteric
3. Adrenal medulla- no synapse only one neuron, releases adrenaline
What three things lead to mass activation of the two neuron chain in the sympathetic ANS?
1.Neural convergence- Axons from many preganglionic cells synapse on a single ganglionic cell
2.Neural divergence- Axons from one preganglionic cell synapse on numerous ganglionic cells
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