Chapter 48 Notes (Nervous System)

Chapter 48 Notes (Nervous System) - Chapter 48 Notes...

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Chapter 48 Notes (Nervous System) 1. Nervous System a. Nervous System = A system which responds to external/internal stimuli through chemical signaling. b. The development (survey) of nervous system i. Radial Symmetry – Nerve Nets Electrical impulse = two directions Cnidarians = Nerve nets Sea stars = Nerve Nets ii. Bilateral Symmetry – Cephalization (Central Nervous System exists) Electrical impulse = one direction Above the level of flatworm (Plathyminthes) 2. Introduction to the neuron a. Neuron = the most basic, functional unit of a nervous system. b. Axon = the part that sends the signal. c. Dendrites = the part that receives the signal. d. Synapses = the distance between the axon and the dendrites. e. Myelin sheath = the fatty layer that covers the dendrites i. Produced from Oligodendrocytes (in the CNS) and Schwann cells (in the PNS). ii. Saltatory conduction = conduction of impulses along myelinated nerve fibers. 3. The Control of Electrical Potential in the Neurons a. Controlled by ion channels – especially the concentration of positive ions under the circumstance at which negative ions do not move. b. In the normal state… i. The inside of a normal cell = negative (-) than the outside. ii. The concentration of Na + : Inside > outside iii. The concentration of K + : Inside < outside c. To balance this potential, the cell should pump Na + ions out of the cell while pump K + into the cell. d.
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Chapter 48 Notes (Nervous System) - Chapter 48 Notes...

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