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Neurophysiology, Neurochemistry, Neuroendocrinology
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Neurophysiology, Neurochemistry, Neuroendocrinology
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PSYCHOLOGY theDOC. KEVIN MOISES jan.moises@usls.edu.ph MW(3:30-4:30PM)
The Neuron Neurophysiology
Structure of Neuron
Neurons
Basic Structure
Soma – cell body of a neuron which contains the nucleus.
Dendrite – branched, treelike structure attached to the soma; receives information from other neurons.
Axon – long, thin, cylindrical structure that conveys information from the soma of a neuron to its
terminal buttons.
Terminal Button – bud at the end of a branch of an axon; forms synapses with another neuron
Synapse – junction between the terminal button of an axon and the membrane of another neuron.
Neurotransmitter – a chemical that is released by a terminal button
,The Neuron - a cell that specializes in communication
A neuron:
a) receives information from other neurons, through its dendrites
b) integrates those signals, and
c) sends messages to other neurons through its terminal buttons
Types of Neurons
Motor Neuron - a neuron located within the central nervous system that controls the contraction of a
muscle or the secretion of a gland. Has its soma in the spinal cord; it receives excitation from other neurons
and conducts impulses along its axon to a muscle
Sensory Neuron - a neuron that detects changes in the external or internal environment and sends
information about these changes to the central nervous system. Highly sensitive to a particular type of
stimulation (light/sound/touch)
Interneuron - A neuron located entirely within the central nervous system. If a cell's dendrites and axons
are contained within a single structure
Sensory neurons (carry messages from sense receptors towards the CNS)
Motor neurons (carry messages fromCNS toward muscles and glands)
Interneurons (carry messages between nerve cells)
Glial Cells
Glia (from the Greek word meaning 'glue') hold the neurons together and provide a supportive framework
for the NS; they are smaller but more numerous than neurons
astrocytes -wrap around presynaptic terminals of a group of functionally related axons
microglia - remove waste material viruses, fungi, microorganisms
oligodendrocytes & Schwann cells - build myelin sheaths that insulate the vertebrate axons
, Steps in Neurotransmission
1. Dendrites/Cell are stimulated to threshold
2. Action potential travels the down axon to presynaptic terminal
3. Vesicles fuse to terminal membrane and release neurotransmitter
4. Neurotransmitter crosses synaptic space
5. It binds to receptor site and alters charge of postsynaptic membrane.
6. The reaction of postynaptic membrane dislodges neurotransmitter from the receptor.
7. Neurotransmitter is deactivated.
a) Diffuses away.
b) Enzymes metabolize it (MAO).
c) It is reuptaken into presynaptic terminal.
Neuronal firing
Dendrites are constantly bombarded with messages from other neurons
These can be excitatory, prompting the neuron to fire off its own message, or inhibitory, decreasing the
probability that the neuron will fire
The power to restrain is just as crucial as important as the power to engage in action
After weighing the input it receives from other neurons, a neuron can decide to send a message to another
neuron
It does so through an electro-chemical process called action potential or neuronal firing.
An action potential is the transmission of the signal down the axon through a complex exchange of sodium
and potassium ions
When the action is over, the positive sodium is pumped back out until next time
Neurophysiology
1. Resting Potential (-70 millivolts)
2. Threshold ( greater than -70 mv)
3. Action Potential ( positive)
4. Hyperpolerization (less than –70 mv)
5. Resting Potential (-70 mv)
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