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Neurons
Nerve cells. Specialized communication cells. Types include sensory (input), motor (movement), interneuron (connects sensory & motor)
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Glial Cells
Supports cells that assist neurons by providing structural support, nutrition, and removal of cells wastes.
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Information is transmitted in the nervous system by the 3 basic types of neurons
Sensory, motor, and interneuron
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The basic components of the neurons and their functions are
Cell body, which contains the nucleus and provides energy for the neuron to carry out its functions; the dendrites, which are short fibers that extend out from the cell body and receive messages from other neurons or specialized cells; and the axon, which is a long, fluid filled tube that carries information from the neuron to other cells in the body, including other neurons, gland, and muscles.
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Within the neuron, info is communicated
In the form of brief electrical impulses called action potentials, which are produced by movement of electrically charged particles, called ions across the membrane of the axon. The resting potential is the state in which a neuron is prepared to activate and communicate its message if it receives sufficient stimulation. For an action potential to occur and a neuron to be activated (depolarized), stimulation must be above the stimulus threshold. In addition, neurons either respond or they don’t, the all-or-non law.
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Communication between neurons may be electrical or chemical. When communication is electrical (in less than 1% of synapse)
The synaptic gap is extremely narrow and special ion channels serve as a bridge between neurons, resulting in almost instantaneous.
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Chemically, communication involves
Neurotransmitters from the synaptic vesicles of one neuron diffusing across the synaptic gap.
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Reuptake is the process in which
Neurotransmitter molecules detach from a postsynaptic neuron and are absorbed by a presynaptic neuron and are reabsorbed by a presynaptic neuron so they can be recycled and used again.
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An excitatory neurotransmitter message
Increases the likelihood that the postsynaptic neuron will activate and generate an action potential
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An inhibitory neurotransmitter message
Decreases the likelihood that the postsynaptic neuron will activate.
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Some important neurotransmitters (and their primary roles) are
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