PSYC 1200 Lecture Notes - Lecture 15: Myelin, Dendrite, Reuptake
20 Jun 2018
School
Department
Course
Professor
Biological Foundations of Behaviour
Your Brain
100 (or 86) billion neurons (nerve cells)
•
Brain cells have from 1,000 to 50,000 connections to other brain
cells
160 trillion connections
○
•
Right side of the brain controls the left side of the body, the left side
of the brain controls the right side of the body
•
Your brain is full of nerve cells, but it has no pain receptors
•
Nervous System
Neurons: Nerve Cells
•
Nerves: bundles of neurons
•
Glial cells: Support Cells
Form blood-brain barrier
○
Repair and protect (remove toxins)
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Accelerate transmission
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Much more…
○
•
The Structure of the Neuron
Dendrite
Receiving incoming signals
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Branches spread out
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•
Cell Body (Soma)
Sustains cell's life
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Processes impulses
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•
Axon
Single long fibre
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Carries outgoing messages
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Myelin Sheath
Layer of fatty, whitish cells
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Speeds up transmission
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Impulse jumps from node to node
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•
Neural Communication
Electrical and chemical transmission•
Electrical transmission (Neural Impulse)•
Chemical transmission (Synaptic Transmission)•
The Neural Impulse
The Resting Potential
Electrically charged chemicals (ions) inside cell and outside
○
Semipermeable cell membrane prevent ions from freely
distributing
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Results in the resting potential (-70 mV)
○
i.e. at rest, the inside of the cell is -70 mV more negative than
the outside
○
•
Action Potential
Stimulation (from sensory input or neighbouring neurons)
makes the membrane more permeable so that more positive
cells enter the neuron (depolarization)
○
If there is enough stimulation and the neuron reaches
threshold (-55 mV), it will "fire"
○
After firing, positive ions get pumped out of the cell to bring it
back to its usual depolarized state
○
But, too many get pumped out creating hyperpolarization
(charge -80 mV)
○
Refractory period
○
Action potential moves like a wave down the axon
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Domino effect
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Does not lose power as it travels
○
•
All or Nothing Law
Intensity determined by the number of neurons firing and the
frequency of the impulses
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•
Cell to Cell Communication
Neurons do not touch•
Impulses cannot travel across space•
Transfer made by chemicals•
Synaptic Transmission
Impulse reaches terminal button•
Neurotransmitters (NT) are released into gap•
NT's attach to receptor sites on postsynaptic membrane•
Certain NT fit specific receptors•
Key and lock analogy•
Effects terminated by
Reuptake
○
Deactivation
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Excitatory or inhibitory effects of NTs
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•
Lecture 09/21
September 26, 2017
10:59 AM
Document Summary
Brain cells have from 1,000 to 50,000 connections to other brain cells. Right side of the brain controls the left side of the body, the left side of the brain controls the right side of the body. Your brain is full of nerve cells, but it has no pain receptors. Electrically charged chemicals (ions) inside cell and outside. Semipermeable cell membrane prevent ions from freely distributing. Results in the resting potential (-70 mv) i. e. at rest, the inside of the cell is -70 mv more negative than the outside. Stimulation (from sensory input or neighbouring neurons) makes the membrane more permeable so that more positive cells enter the neuron (depolarization) If there is enough stimulation and the neuron reaches threshold (-55 mv), it will fire After firing, positive ions get pumped out of the cell to bring it back to its usual depolarized state. But, too many get pumped out creating hyperpolarization (charge -80 mv)
