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Nervous System Def.
| Question | Answer |
|---|---|
| Central Nervous System | contains the brain and spinal cord |
| Peripheral Nervous System | connects the CNS to the other body parts. |
| Neuron | a specialized cell that responds to physical and chemical changes inside or outside of the body. |
| Nervous Tissue | masses of neurons and neuroglial cells. |
| Myelin sheath | a fatty lipoprotein surrounding the axon of a neuron. |
| Nerve impulse | information transmitted in the form of electrochemical changes. |
| CNS | brain and spinal cord |
| PNS | nerves connecting the brain and spinal cord to the peripheral body parts. |
| Sensory receptors | detects changes or stimuli inside or outside of the body. |
| Effectors | muscles and glands |
| Neuroglial cells | fills spaces, provides structure, produces myelin, and can carry our phagocytosis. |
| Microglial cells | scattered throughout the CNS to provide support and phagocytize bacterial cells and cellular debris. |
| Oligodendrocytes | align along nerve fibers, produce myelin on the axons of the CNS |
| Astrocytes | found between neurons and blood vessels, hook extensions on to the CNS to provide structure, join parts, regulate concentrations of nutrients and ions, and form scar tissue. |
| Ependymal cells | form epithelia like membranes around the outside of or the inside lining of the brain and spinal cord. |
| Dendrite | processes that recieve messages, can be numerous |
| Schwann cells | form a myelin sheath around the axons of the PNS |
| Axon | process that sends messages, usually only one per neuron |
| Nerve | bundles of axons |
| Polarized | when the surface of a resting neuron cell membrane is charged. |
| Summation | additive effect of several sub threshold stimuli. |
| Synapse | junction between two communicating neurons. |
| Synaptic cleft | gap between the presynaptic and postsynaptic neuron. |
| Neurofibril | network or threads that are found in the cell body and can extend into the axon; provide structure. |
| Nerve pathway | path of a nerve impulse. |
| Depolarization | decrease in resting potential. |
| Cell Body | portion of a nerve cell that includes a cytoplasmic mass and a nucleus from which nerve fibers extend. |
| Somatic Nervous System | motor pathways of the peripheral nervous system that lead to the skin and skeletal muscles. |
| Autonomic Nervous System | portion of the nervous system that controls the viscera. |
| Chromatophilic substance | membranous sacs within cytoplasm of nerve cells that have ribosomes attached to their surfaces. |
| Neurilemma | sheath formed from Schwann cells on the outside of some axons. |
| Nodes of Ranvier: | narrow gaps between Schwann cells. |
| Trigger zone | a sensitive part of an axonwhere a nerve impulse originates. |
| Unipolar neurons | neurons with a single process extending from the cell body that branches into two, one side acting as an ion and the other as a dendrite. |
| Bipolar neurons | neurons with many processes, one of which is an axon and the other is a dendrite. |
| Multipolar neurons | neurons with many processes, one of which is an axon and the others are dendrites. |
| Ganglia | masses of neuron cell bodies, usually outside of the CNS. |
| Sensory neurons | carry nerve impulses from peripheral body parts into the brain or spinal cord. |
| Interneurons | lie entirely in the brain or spinal cord and direct incoming sensory impulses to the appropriate parts for processing and interpreting. |
| Motor neurons | multipolar neurons that carry nerve impulses out of the brain or spinal cord to the effectors. |
| Potential difference | difference in electric charge between two regions. |
| Resting potential | the potential difference between the region inside the membrane and the region outside the membrane. |
| Threshold stimulus | stimulation level that must be exceeded to elicit a nerve impulse. |
| All-or-none response | if a neuron responds, it responds completely or not at all. |
| Presynaptic neuron | the neuron carrying the impulse or the sender. |
| Postsynaptic neuron | the neuron that recieves the input or the reciever. |
| Synaptic transmission | the process of crossing the synaptic cleft with a message. |
| Neurotransmitters | chemical that an axon end secretes on an effector or another neuron. |
| Synaptic knob | tiny enlargement at the end of an axon that secretes a neurotransmitter. |
| Excitatory | neurotransmitters that increase the postsynaptic membrane permeability to sodium ions and bring it closer to threshold. |
| Inhibitory | neurotransmitters that decrease the postsynaptic membrane permeability to sodium ions and make it less likely that threshold will be reached. |
| Neuronal pools | groups of neurons that make hundreds of synaptic connections with each other and work together to perform a common function. |
| Facilitation | subthreshold stimulation of a neuron that increases responsiveness to further stimulation. |
| Convergence | nerve impulses arriving at the same neuron. |
| Divergence | impulses passing into several output neurons. |
| Sensory fibers | afferent fibers; bring sensory information to the CNS. |
| Motor fibers | efferent fibers; carry impulsesfrom the CNS to the effectors. |
| Sensory nerves | nerves that conduct impulses to the brain or spinal cord. |
| Motor nerves | nerves that conduct impulses to muscles or glands. |
| Mixed nerves | nerves that include both sensory fibers and motor fibers. |
| Reflex arc | the simplest nerve pathway that includes only a few neurons and is the structural and functional basis for the reflexes. |
| Reflex | an automatic, subconscious response to stimuli. |
| Meninges | layered membranes that serve to protect the brain and spinal cord. |
| Dura mater | the outermost layer of the meninges. |
| Arachnoid mater | a thin, weblike membrane without blood vessels that lies between the dura and pia maters. |
| Pia mater | a thin membrane that contains many nerves and blood vessels that nourishes the underlying cells of the brain and spinal cord. |
| Cerebrospinal fluid | a clear watery fluid that is found in the ventricles of the brain, subarachnoid space of the meninges, and the central canal of the spinal cord. |
| Spinal cord | a slender nerve column tha passes downward from the brain into the vertebral column. |
| Spinal nerves | nerves that branch to the various body parts and connect them with the central nervous system. |
| Ascending tracts | tracts in the spinal cord that carry sensory information to the brain. |
| Descending tracts | tracts in the spinal cord that conduct motor impulses from the brain to the musles and glands. |
| Cerebrum | portion of the brain that occupies the upper part of the cranial cavity and provides higher mental functions. |
| Brainstem | portion of the brain that contains the midbrain, pons, and medullar oblongata. |
| Cerebellum | portion of the brain that coordinates skeletal muscle movement. |
| Cerbral cortex | the outer layer of the cerebrum. |
| Diencephalon | portion of the brain in the region of the third ventricle that includes the thalamus and hypothalamus. |
| Cerebral hemispheres | the large paired structures that constitute the cerebrum. |
| Motor areas | the region of the brain from which impulses to muscles or glnads originate. |
| Sensory areas | a portion of the cerebral cortex that recieves and interprets sensory nerve impulses. |
| Association areas | region of the cerebral cortex controlling memory, reasoning, judgement, and emotions. |
Created by:
flick224
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