Nervous System Review Draw, label, and know the functions of the following parts of a neuron: cell body (soma), dendrites, axon, Schwann cells, myelin sheath, nodes of Ranvier, nucleus, synapse. Cell body contains most of the organelles and the nucleus of the neuron – Dendrites receive stimuli from other cells – Axon transmits the action potential (impulse) through the neuron – Schwann cells surround the axon, produce myelin – Myelin sheath layer of lipids (fat) that insulates the axon and speeds up – transduction of the action potential Nodes of Ranvier spaces between Schwann cells, gaps in the myelin sheath – Nucleus contains DNA – Axon terminal end of the axon, contain vesicles of neurotransmitters to – communicate with surrounding cells Synapse space between two cells, where one cell communicates with the next – Describe the charges and sodium and potassium concentrations/movements in a polarized, depolarized, repolarizing, and hyperpolarized neuron and define the preceding Know which transport processes (active transport, facilitated diffusion) involved in each. Resting potential at this time the neuron is polarized (has more negative charge – inside the cell than outside) approximately -70mV, sodium and potassium channels are closed, sodium/potassium pump is pumping sodium OUT of the cell and potassium INTO the cell by active transport, making the outside of the cell relatively positive in comparison to the inside (giving it a negative charge) Threshold approximately -55mV, must be enough input to get the potential above – the threshold in order for an action potential to occur
Nervous System Review Draw, label, and know the functions of the following parts of a neuron: cell body (soma), dendrites, axon, Schwann cells, myelin sheath, nodes of Ranvier, nucleus, synapse. Cell body – contains most of the organelles and the nucleus of the neuron Dendrites – receive stimuli from other cells Axon – transmits the action potential (impulse) through the neuron Schwann cells – surround the axon, produce myelin Myelin sheath – layer of lipids (fat) that insulates the axon and speeds up transduction of the action potential Nodes of Ranvier – spaces between Schwann cells, gaps in the myelin sheath Nucleus – contains DNA Axon terminal – end of the axon, contain vesicles of neurotransmitters to communicate with surrounding cells Synapse – space between two cells, where one cell communicates with the next Describe the charges and sodium and potassium concentrations/movements in a polarized, depolarized, repolarizing, and hyperpolarized neuron and define the preceding Know which transport processes (active transport, facilitated diffusion) involved in each. Resting potential – at this time the neuron is polarized (has more negative charge inside the cell than outside) approximately -70mV, sodium and potassium channels are closed, sodium/potassium pump is pumping sodium OUT of the cell and potassium INTO the cell by active transport, making the outside of the cell relatively positive in comparison to the inside (giving it a negative charge) Threshold – approximately -55mV, must be enough input to get the potential above the threshold in order for an action potential to occur
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