Notes From Reading
CHAPTER 3: THE BIOLOGICAL BASIS OF BEHAVIOR
I. Communication in the Nervous System
A. Nervous Tissue: The Basic Hardware
1. 2 Major Categories for Cells in Nervous System
a. Glia – cells found throughout the nervous system that provide structural
support and insulations for neurons. Help maintain the chemical
environment of the neurons
b. Nuerons- the individual cells in the nervous sytem that receive,
integrate, and transmit info. Permit communication (mostly within other
neurons) – only sensory organs revieve signals from outside the nervous
2. Parts of a Neuron:
a. Soma (cell body) – contains the nucleus and muc of the chemical
machinery common to most cells.
b. Rest of neuron dedicated to handling info.
c. Dendrites – parts of the neuron that are speacialized to receive info.
d. Axon – info travels from dendrites to axon, which are the long thin fiber
that transmit signals away from the soma to other neurons or muscles
e. Myelin sheath – many axons wrapped in cells with a high concentration
of myelin. Insulating material, from glial cells, that encases some
neurons. Speeds up transmissiono of info.
i. Multiple Scleroris due to deterioration of myelin sheath.
f. Terminal buttons – small knobs that secrete chemicals called
neurotransmitters. At end of axons in clusters.
g. Synapse – point at which neurons connect. Junction where info is
transmitted from one neuron to another.
B. The Neural Impulse: Using Energy to Send Information
1. The Nueron at Rest: A Tiny Battery
a. Neural impulse is a complex electrochemical raction.
b. The resting potential of a neuron is it’s stable, negative charge when the
cell is inactive. (Potential Energy of a Nueron).
2. The Action Potential – brief shift in a nueron’s electrical charge that travels
along an axon.
a. Absolure Refractory Period – the minimum length of time after an action
potential during which another action potential can not begin (down
3. The All or None Law
a. Either the neuron fires or it doesn’t, and its action potentials are always
the same. i.e. weaker stimuli don’t produce smaller action potentials.
b. However, they can change the rate of action potentials. A stronger
stimulus will make for more rapid action potentials in a shorter period of
C. The Synapse: Where Nuerons Meet
1. Sending Messages: Chemicals as Couriers
a. Synaptic Cleft – a microscopic gap between the terminal button of one
neuron and the cell membrane of another neuron.