System

LECTURE NOTES I. The Nervous System: On Being Wired A. Phineas Gage story: The brain’s influence on personality; the nervous system serves as the base for behaviors, emotions, and cognitions. B. Neurons: Into the Fabulous Forest 1. Neurons: the nerve cells of the body; the metaphoric tree. a. Cell Body: contains the nucleus which generates energy b. Dendrites: receive incoming messages from adjourning cells (roots). c. Axon: carry messages away from the cell body (trunk). d. Terminals (terminal buttons): bulb shaped structure at the end of the axon. e. Myelin: fatty substance around axons that facilitate conduction. f. Glial cells: remove dead neurons and waste products from the nervous system. g. Afferent neurons: sensory input. h. Efferent neurons: motor output. i. SAME: Sensory = Afferent, and Motor = Efferent. C. The Neural Impulse: “The Body Electric” 1. Neural Impulse: message traveling along the neuron; between 2 and 225 miles an hour. 2. An Electrochemical Voyage. a. Neuron resting potential: -70 millivolts (negative charge). b. Depolarized: action of the cell while it becomes positively charged. c. Action potential: positively charged neuron returning to the resting state of being negatively charged. The “message” is sent 3. Firing: How Messages Voyage from Neuron to Neuron a. Neuron Firing: neurons attempt to transmit messages to other neurons, muscles or glands. b. Threshold: Each neuron has a threshold; the cell will not fire until the threshold is reached. c. All or None Principle: When the threshold is reached, the neuron fires an impulse of the same strength. d. Refractory Period: a period of time when the neuron will not fire; period of recovery during which positive sodium is not allowed to pass through the neural membrane. 4. The Synapse: On Being Well Connected a. Synapse: junction (fluid filled gap) between neurons. D. Neurotransmitters: The Chemical Keys to Communication 1. Synaptic Vesicles: sacs in the axon terminals, which contain...