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Chapter 3

PSY100H1 Chapter Notes - Chapter 3: Multiple Sclerosis, Resting Potential, Myelin

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CHAPTER 3 – Genetic and Biological Foundations
Nervous system
-A communication network comprised of billions of specialized cells, evaluates info from the external
world then produces behaviours or makes bodily adjustments to adapt to the environment
-The basic unit of the nervous system
- Cells that specialize in communication
- Operate through electrical impulses and communicate with other neurons through chemical signals
-They differ from most other cells because they are excitable
-Have 3 functions:
oReception: take in info from neighboring neurons
oConduction: integrate those signals
oTransmission: pass signals to other neurons
-Come in a wide assortment of shapes and sizes, but typically share 4 structural regions that
assist the neuron’s communication functions
1) Dendrites: branchlike extensions of the neuron that detect info from other neurons
2) Cell body: in the neuron, where info from thousands of other neurons is collected and
3) Axon: a long narrow outgrowth of a neuron by which info is transmitted to other neurons
4) Terminal buttons: small nodules at the end of axons that release chemical signals from
the neuron to an area called synapse
Synapse: the site for chemical communication between neurons
Lipids: double layer of fatty molecules of the membrane, the boundary of a
Membrane: involved in communication between neurons by regulating the
concentration of electrically charged molecules that are the basis of the
neuron’s electrical activity
-A neuron: messages are received by the dendrites, processed in the cell body, transmitted along
the axon, and sent to other neurons via chemical substances released from the terminal buttons
Types of Neurons
1) Sensory neurons: these afferent neurons detect info from the physical world and pass
that info along to the brain, usually via the spinal cord
Afferent neurons: receptors send signals from the body to the brain to
produce a response
2) Motor neurons: these efferent neurons direct muscles to contract or relax, thereby
producing movement
Efferent neurons: receptors send signal that travel from the brain to the
3) Interneurons: these neurons communicate only with other neurons, typically within a
specific brain region, communicate within local or short-distance circuits, that is,
interneurons integrate neural activity within a single area rather than transmitting info to
other brain structures or to the body organs
- Together, sensory and motor neurons control movement
-The nerves that provide info from muscles are referred to as somatosensory, which is the general
term for sensations experienced from within the body
- Neurons don’t communicate randomly or arbitrarily, they selectively communicate with other
neurons to form circuits or neural networks. These networks develop through maturation and
experience, forming permanent alliances among groups of neurons
Action potentials cause neuronal communication
-Action potential (neuronal firing): the neural impulse (electrical signal) that passes along the axon
and subsequently causes the release of chemicals from the terminal buttons to other neurons
The resting membrane potential is negatively charged
-Resting membrane potential: the electrical charge of a neuron when it is not active
-The differential electrical charge inside and outside of the neuron is a condition known as
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