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45 Cards in this Set

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Neuron
A nerve cell. The structural and functional unit of the Nervous System.
Afferent Neurons
Sensory. Nerve cells that send impulses from receptors to the central nervous system.
Efferent Neurons
Motor. Nerve cells that send impulses from the Central Nervous System to skeletal muscles, cardiac muscles, smooth muscles or glands.
What are the Functional types of Neurons of the Periferal Nervous System?
Afferent and Efferent
What are the types of Neurons of the Central Nervous System?
Interneurons, Internuncial Neurons, Association Neurons, and Commissural Neurons.
Interneurons
Nerve cells that are located in the spinal cord and are involved in a reflex arc. These nerve cells act as a bridge within the spinal cord to carry impulses from sensory neurons directly to motor neurons within the PNS.
Internuncial Neurons
Nerve cells that communicate between two other neurons conducting impulses that are ascending or descending in the spinal cord.
Association Neurons
Nerve cells that carry impulses between the Gyri (ridges) within the same cerebral hemisphere (same side of the cerebrum of the brain).
Commissural Neurons
Nerve cells that carry impulses from the Gyri in one cerebral hemisphere to the corresponding gyri in the opposite cerebral hemisphere.
Multipolar Neuron
Several dendrites and one axon.
Bipolar Neuron
One dendrite and one axon
Unipolar Neuron
Axon and dendrite fuse into a single process in the cell body then divides into two branches, one functioning as a dendrite and one functioning as an axon.
What are the anatomical components of a neuron?
Cell body, Dendrite, Axon.
Neuron Cell Body
Contains a nucleus, nucleolus, and other typical organelles. Inloved in metabolism, growth and repair of Neuron.
Dendrite
Cytoplasmic extension which is highly branched. Conducts impulses toward the cell body. Peripheral sensory neurons have receptors at the tips of the dendrites. May be myelinated or unmyelinated.
Axon
Cytoplasmic extension which may be as long as a meter in length or as small as a few millimeters. Conducts impulses away from cell body. Surrounded by a selectively semi-permeable membrane (axolemma). May be myelinated or unmyelinated. Branches, called axon collaterals are found near the end of the axon. Terminates into axon terminals.
Axon Terminals
Contains synaptic vesicles that store chemicals called neurotransmitters. Neurotransmitters are released from the axon terminal and migrate to the neiboring cells (muscle, fiber, gland, or another neuron, altering its activity.
What cells produce Myelin?
Produced by Neuroglia Cells. Schwann Cells in the PNS and Oligodendrocytes in the CNS.
Myelin Sheath
Wraps directly around the neural process. The outer portion is termed the Neurilemmal Sheath (only in PNS). Plays a role in nutrition of the axon and regeneration of an injured axon. Allows nerve impulses to conduct down the process faster.
White Matter
Myelinated processes of many neurons which run together and give a white appearance upon dissection.
Grey Matter
Non-myelinated neuron cell bodies which "clump" together and give a gray appearance upon dissection.
Nodes of Ranvier
Gap where the myelin sheath is interrupted. The axon/dendrite is exposed in this nodal region.
Salutatory Conduction
Impulses utilizing Nodes of Ranvier to speed the transmission. The impulse "hops" from node to node which is quicker than transmitting down the entire length of the axion.
Synapse
The junction between an axon terminal of one neuron with a muscle fiber, gland, or dendrite, axon or cell body of another neuron. The site where transmission of an impulse (action potential) occurs.
What are the components of a Synapse?
Presynaptic Terminal, Postsynaptic Terminal, Synaptic Cleft, Synaptic Vesicles, and Mitochondria.
Presynaptic Terminal
Distal end of the axon terminal, characterized by a bulb-like structure, of the neuron conducting the impulse to the next cell. Neurotransmitters are released from this location to activate the next cell.
Postsynaptic Terminal
The location on the cell receiving the impulse. This can be on the dendrites, cell body, or axon of a neuron, or a gland or muscle fiber. Receptors for the neurotransmitters are located on the membrane surface.
Synaptic Cleft
Region between the presynaptic terminal and the postsynaptic terminal. The neurotransmitters must cross this region in order to transfer the impulse (action potential) to the postsynaptic terminal.
Synaptic Vesicles
Vesicles (containers) containing neurotransmitters which are located in the presynaptic terminal.
Mitochondria
Supplies the necessary energy for migration of the synaptic veicles to the edge of the presynaptic terminal's axolemma and release the neurotransmitter from the synaptic vesicles into the synaptic cleft.
What are the types of Synapses?
Axodendritic, Axosomatic, Axoaxonic, Neuromuscular, Neuroglandular
Axodendritic Synapses
Junction between an axon terminal of one neuron with a dendrite of another neuron
Axosomatic Synapses
Junction between an axon terminal of one neuron and a cell body (soma) of another neuron.
Axoaxonic Synapses
Junction between an axon terminal of one neuron and an axon of another terminal.
Neuromuscular Synapses
Junction between an axon terminal of one neuron (efferent neuron) and a muscle fiber.
Neuroglandular Synapses
Junction between an axon terminal of a neuron and a gland.
Sensory Receptors
Distal end of a dendrite of a peripheral afferent neuron.
What are the functions of Sensory Receptors?
Structures located in various parts of the body that send information from the external and internal enviroment to the spinal cord and brain for processing. The sensory receptors convert a stimulus into an electrical impulse or action potential.
What are the types of Somatic Sensory Receptors?
Free Nerve Ending, Merkel's Tactile Disks, Meissner's Corpuscle, Pacinian Corpuscle, Golgi Tendon Organ, and Muscle Spindle.
Free Nerve Ending
Pain, temperature and crude touch. Epidermis/Dermis line
Merkel's Tactile Disks
Discrimitive touch. Epidermis
Meissner's Corpuscle
Simple touch. Epidermis/Dermis line
Pacinian Corpuscle
Pressure. Dermis (subpapillary plexus)
Golgi Tendon Organ
(Neuromuscular Spindle) responds to tension of the skeletal muscle fibers.
Muscle Spindle
(Neuromuscular Spindle) Responds to stretching of a muscle