nervous system
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36 terms
Terms | Definitions |
|---|---|
 nervous system | chief coordinator, acts by chemical changes and electrical impulses |
| central nervous system | brain and spinal cord |
| peripheral nervous system | cranial nerves and spinal nerves |
| cranial nerves | carry impulses to and from the brain |
| spinal nerves | carry impulses to and from the spinal cord |
| somatic nervous system | controlled voluntarily, affects skeletal muscle |
| autonomic nervous system | involuntary, controls smooth muscle, cardiac muscle, and glands, has 2 subdivisions sympathetic and parasympathetic |
| sympathetic nervous system | prepares body for energy expending stressful or emergency situations |
| parasympathetic nervous system | maintains homeostasis, conserves body energy, more active under ordinary, restful situations |
| neuroglia or glial cells | fill spaces, support neurons, and insulate neurons, can reproduce, and act as phagocytes |
| nerve cell or neuron | functional unit of the nervous system, specialized to react to physical and chemical changes, functions to conduct nerve impulses to other neurons and to cells outside the nervous system |
| dendrites | fibers that conduct impulses to the cell body, receive stimuli, receive changes |
| axons | fibers (one per neuron) that carry impulses away from the cell body |
| myelin sheath | fatty material that insulates fiber, covers some axons |
| schwann cells | located in the myelin sheath, produces myelin, wraps around the axon |
| nodes | gaps between the schwann cells, important in speeding the conduction of nerve impulses |
| neurolemma | outermost membrane of schwann cells, thin coating, helps some peripheral nerves repair themselves after injury |
| white fibers | myelinated fibers found in the white matter of the brain and spinal cord |
| gray matter | has no myelin |
| sensory or afferent neurons | neurons that conduct impulses to the spinal cord and brain |
| motor or efferent neurons | carry impulses away from the CNS to muscles and glands |
| polarized | inside of neuron is negative, the oustide is positive (when neuron is at rest) |
| Na+ and K+ | needed for nerve impulses, at rest Na are more concentrated on the outside of the membrane and K is more concentrated on the inside |
| action potential | the inside negative ions rush outside, and the outside positive ions rush inside |
| depolarization | as the Na flow into the cell, they raise the charge on the inside of the membrane |
| repolarization | K leaves the cell, electrical charge returns to its resting state, and Na and K return to original postitions on either side of the membrane |
| synapse | the junction between 2 neurons, or from a neuron to an effector cell |
| neurotransmitters | carry impulses across the gap (synapse) to the next cell |
| 4 neurotransmitters | epinephrine, norepinephrine, dopamine, acetylcholine |
| neurotransmitters are turned off by? | enzymes, diffusion, recycled |
| spinal cord | long, thin nerve column, extends from foramen magnum to level of first lumbar vertebrae |
| how is spinal cord protected? | by vertebral column, meninges, and cerebral spinal fluid |
| reflex arc | afferent, efferent, RSCNE |
| RSCNE | receptor, sensory, CNS, motor neuron, effector |
| reflex | rapid, simple, automatic response, specific- a given stimulus always produces the same response |
| spinal nerves | 31 pair, numbered according to the level of spinal cord where they originate, exit through vertebral column, branch out to body parts to connect them with CNS |
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