PSYA01H3 Chapter Notes - Chapter 3: Myelin, Neuroglia, Springform Pan

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Published on 5 Aug 2018
School
Department
Course
Neuroscience and Behavior
Neurons: The Origin of Behavior
Approx 100 billion nerve cells in your brain
Neurons - All your thoughts, feelings, and behavior springform a cell in the brain
to take information and produced some kind of output
Components of the Neuron
Cells come in all shapes and sizes
Cajal discovered that neurons are complex structures and are composed of
three basic parts: the cell body, dendrites, and axons
The cell body is the largest component of the neuron
The cell body coordinates the information processing tasks and keeps the cell
alive
Functions such as protein synthesis, energy production and metabolism
take place here
The cell body contains a nucleus which houses chromosomes that
contain your DNA or the genetic blueprint of Who You Are
The cell body is surrounded by a porous cell membrane that allows some
molecules to flow into and out of the cell
Neurons have two types of specialized extensions of the cell membrane that
allow them to communicate: dendrites and axons
Dendrites
Receive information from other neurons and relay it to the cell body
Axon
Carries information to other neurons muscles or glands
Can be very long, even stretching upto a metre
Axon is covered by a myelin sheath
Myelin Sheath
An insulating layer of fatty material
composed of glial cells
Glial Cells
Support cells that are found in the nervous system
Some glial cells digest parts of dead neurons
Some glial cells provide physical and nutritional support for neurons
Others Ford Milan to help the axon carry information more efficiently
Cajal Also observed that the dendrites and axons of neurons do not actually
touch each other
There is a small gap between the axon of one neuron and the dendrites or cell
body of another
The Gap is called the synapse
Most adults have 100 to 500 trillion synapses
Major Types of Neurons
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Sensory Neurons - Receive information from the external world and convey this
information to the brain via the spinal cord
Have specialized endings on their dendrites that receive signals for light
sound touch taste and smell
Motor Neurons - Carry signals from the spinal cord to the muscles to produce
movement
these neurons often have long axons that can stretch to muscles at our
extremities
Interneuron - Connect sensory neurons, motor neurons, or other interneurons
Some interneurons carry information from Sensory neurons into the
nervous system
Others carry information from the nervous sister to motor neurons
Interneurons work together and small circuits to perform simple tasks
Identifying the location of a sensory signal
Recognizing a familiar face
Neurons Specialized by Location
Neurons Specialized depending on their location
Purkinje cells
Type of interneuron that carries information from the cerebellum to the
rest of the brain and spinal cord
Have dense elaborate dendrites that resemble bushes
Pyramidal cells
Found in the cerebral cortex
Have a triangle cell body and a single long dendrite among many smaller
dendrites
Bipolar Cells
A type of sensory neuron found in the retinas of the eyes
Have one single axon and one single dendrite
Electrochemical Actions of Neurons: Information Processing
The communication of information within and between neurons proceed in two
stages: Conduction and Transmission
Conductions
The movement of an electric signal within neurons, from the dendrites to
the cell body, then throughout the axon
Transmission
The movement of electric signals from one neuron to another over the
synapse
Both conduction and transmission is what scientists generally referred to as
electrochemical action of neurons
Electric Signaling: Conducting Information within a Neuron
How smaller pores that act as channels to allow small electrically charged
molecules (ions) to flow in and out of the cell
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The Resting Potential: The Origin of the Neuron’s Electrical Properties
Neuron have a natural electric charge called the resting potential
The difference in electric charge between the inside and outside of a
neuron cell membrane
Arises from the difference in concentrations of ions inside and outside the
neuron cell membrane
The Action Potential: Sending Signals across the Neuron
Biologist noticed that they could produce a signal by stimulating the axon with a
brief electric shock
Resulted in the conduction of an electric impulse down the length of the Axon
Action Potential - An electric signal that is conducted along the length of the
neuron’s axon to a synapse
Action potential occurs only when the electric shock reached a certain
level
After the action potential reaches its maximum, the membrane channels
return to their original state and the potassium flows out until the axon
returns to its resting potential
Refractory Period - The time following an action potential during which a new
action potential cannot be initiated
Chemical Signaling: Transmission between Neurons
Axons usually end in terminal buttons
Knob like structures that Branch out from an axon
Filled with tiny bags that contain neurotransmitters
Neurotransmitter - Chemicals that transmit information across the
synapse to a receiving neuron’s dendrites
The dendrites of the receiving neuron contain receptors
Parts of the cell membrane that receives neurotransmitters and
either initiate or prevent a new signal
Types of Functions of Neurotransmitters
More than 60 chemicals play a role in transmitting information throughout the
brain and body
Acetylcholine - Involved in voluntary motor control
Found in neurons of the brain and in the synapse where axons connect to
muscles and body organs such as the heart
Activate muscles to initiate motor Behavior but it also contributes to the
regulation of attention, learning, sleeping, dreaming, and memory.
Dopamine - regulates motor Behavior, motivation, pleasure, and emotional
arousal.
Normally associated with addiction
high levels of dopamine have been linked to schizophrenia
low levels of dopamine have been linked to Parkinson's disease
Glutamate - major excitatory neurotransmitter in the brain
Enhances the transmission of information between neurons
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Document Summary

Approx 100 billion nerve cells in your brain. Neurons - all your thoughts, feelings, and behavior springform a cell in the brain to take information and produced some kind of output. Components of the neuron three basic parts: the cell body, dendrites, and axons. Cells come in all shapes and sizes. Cajal discovered that neurons are complex structures and are composed of. The cell body is the largest component of the neuron. The cell body coordinates the information processing tasks and keeps the cell. Functions such as protein synthesis, energy production and metabolism alive take place here. The cell body contains a nucleus which houses chromosomes that contain your dna or the genetic blueprint of who you are. The cell body is surrounded by a porous cell membrane that allows some molecules to flow into and out of the cell allow them to communicate: dendrites and axons. Neurons have two types of specialized extensions of the cell membrane that.

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