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The Brain and Behavior
Basic terminology
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Neuron – receive, integrate, transmit info signals
Soma – (Greek for body) cell body
Dendrites – specialized to receive info
Axon – thin fiber that transmits signals away from soma
to other neurons, muscles or glands
• Myelin sheath – insulating material encasing axons
• Glial cells (Schwann’s cells) – make myelin sheath
• Terminal buttons – secrete neurotransmitters
The basic hardware of nervous
tissue
DIFFERENT TYPES OF
NEURONS
• Sensory neurons or Bipolar neurons carry messages
from the body's sense receptors (eyes, ears, etc.) to the
CNS.
• Motoneurons or Multipolar neurons carry signals from
the CNS muscles and glands.
• Interneurons or Pseudopolare (Spelling) cells form all
the neural wiring within the CNS. These have two axons
(instead of an axon and a dendrite). One axon
communicates with the spinal cord; one with either the
skin or muscle.
GLIAL CELLS
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Glial cells make up 90 percent of the brain's cells.
Glial cells are nerve cells that don't carry nerve impulses.
The various glial (meaning "glue") cells perform many important functions…
including:
– digestion of parts of dead neurons,
– manufacturing myelin for neurons,
– providing physical and nutritional support for neurons
Neural impulse
• Electrochemical reaction
• + charged sodium and potassium ions –
charged chloride ions flow back and forth
across the cell membrane
• They do not cross at the same rate
Neural Impulse: Resting Potential
Neural Impulse: Action Potential
Synapse
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Neurotransmitter molecules, released by synaptic vesicles, cross the tiny
synaptic space (or cleft) between the axon terminal (or synaptic knob)
of the sending neuron and the dendrite of the receiving neuron, where they
latch on to a receptor site, much the way a key fits into a lock. This is how
they pass on their excitatory or inhibitory messages.