Fundamentals of Nervous System Flashcards
Consists of nerve fibers that conduct impulses from the CNS to muscles and glands.
Motor (efferent) division
Consists of motor nerve fibers to smooth and cardiac muscle and glands; it is involuntary; equivalent to the autonomic nervous system
Visceral motor
Consists of the brain and spinal cord; functions for integration and as the control center.
Central nervous system
Consists of the cranial nerves, spinal nerves, and ganglia; provides communication lines between the CNS and the rest of the body.
Peripheral nervous system
Consists of nerve fibers that conduct impulses from the CNS to skeletal muscles; under voluntary control.
Somatic motor
Consists of somatic and visceral nerve fibers that conduct impulses from receptors to the CNS.
Sensory (afferent) division
The single, long extension from a nerve cell that conducts impulses away from the cell body.
Axon
The whitish, fatty covering around some nerve fibers that allows them to conduct impulses faster.
Myelin sheath
A type of neuroglia cell that produces the myelin sheath around nerve fibers in the PNS.
Schwann cell
Diffusely branching extensions from the cell body that are the main receptive or input regions.
Dendrite
Supporting cells of the nervous system.
Neuroglia
The portion of a nerve cell where the nucleus is located and most metabolic processes occur.
Cell body
The site at which neurons communicate across a narrow gap between the cells.
Synapse
Regions in the nervous system that are composed primarily of myelinated nerve fibers.
White matter
A highly specialized cell that conducts nerve impulses from one part of the body to another.
Neuron
The gap that exists in the myelin sheath between adjacent Schwann cells on myelinated fibers.
Node of Ranvier
The cell whose axon terminal releases neurotransmitter into the synapse.
Presynaptic neuron
Regions composed primarily of unmyelinated nerve fibers and cell bodies.
Gray matter
The cell which receives information across a synapse.
Postsynaptic neuron
A cable-like organ in the PNS that consists of many axons bundled together.
Nerve
Any long axon.
Nerve fiber
Has one axon and one dendrite.
Bipolar
Has many dendrites and one axon.
Multipolar
Appears to have only one process.
Unipolar
Forms most sensory neurons.
Unipolar
Found in retina and cochea.
Bipolar
Includes most of the motor neurons.
Multipolar
Located entirely in CNS.
Interneurons
Carry impulses away from CNS.
Motor
Carry impulses towards CNS.
Sensory
Have cell body in PNS.
Sensory
Have cell body in CNS.
Motor and Interneurons
Also called association neurons.
Interneurons
Also called efferent neurons.
Motor
Also called afferent neurons.
Sensory
Phagocytic cells
Microglia
Surround neuron cell bodies in ganglia
Satellite cells
Line the ventricles; help form CSF
Ependymal cells
Make myelin in PNS
Schwann cells
Make myelin in CNS
Oligodendrocytes
Control concentration of ions and neurotransmitters; form blood-brain barrier
Astrocytes
The outer covering around an entire nerve.
Epineurium
The lipoprotein covering around an axon that is made by a Schwann cell.
Myelin sheath
The most external layer of a Schwann cell as it wraps around a neuron.
Neurilemma
A group of axons bundled together.
Fascicle
The connective tissue around the myelin sheath of an axon.
Endoneurium
A nerve fiber.
Axon
The connective tissue layer that surrounds a fascicle.
Perineurium
Site where the stimulus acts and initiates the steps of the reflex arc.
Step 1: Receptor
Carries information from the body to the integration center.
Step 2: Sensory neuron
Usually an interneuron that serves as a link between afferent and efferent neurons.
Step 3: Integration center
Carries impulse from integration center to a muscle or gland.
Step 4: Motor neuron
Responds to impulses by contracting or secreting.
Step 5: Effector
True or False: In general, neurons do not divide after the fetal period.
True
Which has the best chance of healing?
a PNS nerve fiber
Regrowth of regenerating nerve fibers is guided by the:
neurilemma
What happens to the portion of a nerve fiber distal to the site of injury?
it degenerates and is engulfed by macrophages
How quickly does the regenerating end of an axon grow?
1.5 mm/day
Why don’t neurons in the CNS regenerate when damaged?
both a and b are true
a) The neuroglia don’t form bands to guide the regrowing axons.
b) The neuroglia secrete growth inhibiting chemicals.
An autoimmune disease in which the immune system attacks the myelin around axons in the CNS, leading to sensory disorders and weakened musculature.
Multiple sclerosis
Extremely painful disorder caused by compression of the trigeminal nerve of the face.
Tic douloureux
Responsible for 60% of tumors that originate in the brain.
Gliomas
