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Date Submitted: 04/27/2016 06:04 PM
The Nervous System
Neuron to Reflex Arc:
1. Identify and give functions for the following: dendrite, cell body, and axon
a. Dendrite: part of a nerve cell which conducts signals toward the cell body
b. Cell body: part of a nerve cell which contains the nucleus
c. Axon: part of a nerve cell which conducts impulses away from the cell body
2. Distinguish between sensory, motor, and interneuron with respect to structure and function
d. Sensory neuron (afferent neuron): type of neuron which takes a message from a sense organ to the CNS.
e. Motor neuron (efferent neuron): type of neuron which takes a message away from the CNS to an effector (muscle or gland), it has short dendrites and a long axon
f. Interneuron (association): type of neuron found completely within CNS which conveys messages between parts of the system; has short dendrites and long/short axon
3. Explain transmission of a nerve impulse through a neuron, using the following terms:
g. Resting and action potential: resting potential is the polarity across the plasma membrane of a resting neuron due to an unequal distribution of ions (-65mV), action potential is polarity changes due to the movement of ions across the plasma membrane of an active neuron. Action potential can be caused by stimulation by an electric shock, a sudden difference in pH, or a pinch.
h. Depolarization and repolarization: depolarization occurs when stimulation of an axon causes the gates of sodium channels to open temporarily (becomes permeable), allowing Na+ ions to flow into the axon; this causes the action potential to swing up to +40mV. Repolarization occurs when the potassium gates open and K+ leaves the inside of the axon, causing the action potential swing to drop from +40mV to –65mV.
i. Sodium and potassium gates (refer to above)
j. Sodium-potassium pump: a protein carrier which pumps Na+ out and K+ across the axon membrane. It is...