Download Nervous System Vocabulary KEY Afferent Neurons: (Sensory

Nervous System Vocabulary KEY
1. Afferent Neurons: (Sensory neurons) - carry impulses from sensory receptors in the
internal organs
or skin to the CNS. The cell bodies are always found in a ganglion outside the CNS. They keep
us informed about what is happening inside & outside of the body.
2. Association Neurons (interneurons): They connect the motor & sensory neurons in neural
pathways.
Their cell bodies are always located in the CNS.
3. Astrocytes: (support cells or neuroglia cells) star-shaped cells that make up almost ½ of all
of the
neural tissue. They form a living barrier b/w capillaries & neurons & form a barrier to help
protect the neurons from harmful substances that might be in the blood. They also help control
the chemical environment in the brain by picking up excess ions & recapturing released
neurotransmitters.
4. (Autonomic Nervous System: involuntary nervous system): - regulates events that are
automatic,
like the activities of smooth & cardiac muscle & visceral glands. It is subconscious & has 2
neurons b/w CNS & effector. It has 2 parts the sympathetic & parasympathetic systems.
5. Autonomic Reflexes: regulate the activity of smooth muscles, the heart, & glands. Ex.
Digestion, elimination, blood pressure, & sweating.
6.
7. Central Nervous System (CNS): consists of the brain & spinal cord & interpret incoming
sensory information & issue instructions based on past experience & current conditions.
8. Dendrites: the neuron processes that convey incoming messages (electrical signals) toward
the cell body.
9. Depolarization: the inward rush of sodium ions inside the cell membrane changes the
polarity of the neuron’s membrane to a positive & the outside is less positive. If the stimulus is
strong enough the depolarization activates the neuron to initiate & transmit an action potential or
nerve impulse in the neurons.
10. Efferent Neurons: (Motor neurons): - neurons carrying impulses from the CNS to the
viscera or muscles & glands. Their cell bodies are always located in the CNS.
11. Ependymal Cells: (support cell-glia cell): - line the cavities of the brain & spinal cord. The
beating of their cilia helps to circulate the cerebrospinal fluid that fills those cavities & forms a
protective cushion around the CNS.
12. Ganglia: small collections of cells bodies.
13. Glia: (neuroglia): - support cells in the CNS that support, insulate & protect the delicate
neurons of the CNS. “nerve glue”
14. Grey Matter: contains mostly unmyelinated fiber & cell bodies with in the CNS.
15. Microglia: glia cell that’s spider-like phagocytes that dispose of debris, including dead brain
cells & bacteria.
16. Myelin: most long nerve fibers are covered with a whitish, fatty material called myelin
which has a waxy appearance. I t protects & insulates the fibers & increases the transmission
rate of nerve impulses.
17. Nerves: bundles of neurons, can carry afferent, efferent, or both types of neurons at the
same time.
18. Neurilemma: Part of a Schwann cell, external to the myelin sheath.
19. Neuroglia: (nerve glue) support cells in the CNS are lumped together as neuroglia. It’s the
glue that holds the nervouse system together. It provides the neurons of the nervous system
w/support, protection, access to nutrients, & numerous other valuable services.
20. Nissl Substance: the rough ER of a neuron’s cell body.
21. Nodes of Ranvier: Gaps or indentions at regular intervals alone the myelin sheath b/w each
Schwann cell.
22. Oligodendrocytes: glia that wrap their flat extensions tightly around the nerve fibers
producing myelin sheaths (fatty insulating coverings).
23. Parasympathetic Autonomic NS: responsible for bringing all of the physiological changes
that occur w/in the body during the fight-or-flight (sympathetic NS) back to normal.
24. Peripheral Nervous System (PNS): The part of the nervous system outside the CNS,
consist mainly of the nerves that extend from the brain & spinal cord. Spinal nerves carry
impulses to & from the spinal cord. Cranial nerves carry impulses to & from the brain.
25. Polarized: The plasma membrane of a resting, or inactive neuron has fewer positive ions
sitting on the inner face of the neuron’s plasma membrane than there are on its outer face in the
tissue fluid that surrounds it.
26. Proprioceptors: sensory receptors found in the muscles & tendons that detect the amount of
stretch, or tension,is in skeletal muscles, tendons, & joints. They send this information to the
brain to make the proper adjustments & maintain balance & normal posture.
27. Reflex Arc: neural pathway where reflexes occur.
28. Repolarization: when the plasma membrane becomes impermeable to sodium ions, but
permeable to potassium ions. The potassium ions are allowed to diffuse out of the neuron into
the tissue fluid & they do so very rapidly. This outflow of positive ions from the cell restores the
electrical conditions at the membrane to the polarized or resting state, an event called
repolarization. Until repolarization occurs, a neuron cannot conduct another impulse.
29. Saltatory Conduction: a nerve impulse leaps from node to node. It is faster than
continuous conduction & nerve impulses traveling on myelinated fibers are faster than those
traveling on unmyelinated fibers.
30. Satellite cells: supporting cells in the PNS that act as protective, cushioning cells for the
ganglia. .
31. Schwann Cells: support cell in the PNS that form the myelin sheaths around nerve fibers.
32. Somatic Nervous System: (voluntary nervous system) allows us to consciously control our
skeletal muscles. Can be conscious or subconscious. Has a single neuron b/w CNS & effector.
33. Somatic Reflexes: include all reflexes that stimulate the skeletal muscles. Ex. When you
move your hand off of a hot plate.
34. Sympathetic NS. Division of the autonomic NS associated w/ the fight or flight response.
We are in this mode most of the time in our daily lives.
35.Types of sensory receptors: Motor or efferent receptors; Sensory or afferent sensors; &
association or interneuron` sensors.
36.White Matter: Consists of dense collections of myelinated fibers (tracts) within the CNS.