PSYC 1000U Lecture Notes - Lecture 3: Central Nervous System, Insomnia, Acetylcholine
September 25, 2017
The Brain
Lecture 3
The Central Nervous System
o Neurons
o Cell body – cells life-support center
o Dendrites – receives messages from other cells
o Axon – passes message away from the cell body to other neurons, muscles, or
glands
o Neural Impulses – action potential, electrical signal traveling down the axon
o Terminal Branches of Axon – form junctions with other cells
o Myelin Sheath – Covers the axon of some neurons and helps speed neural
impulses
Neural communication
o Each neuron receives excitatory and inhibitory signals from many other neurons
o When excitatory signal minus the inhibitory signals exceed a minimum intensity
(threshold) the neurons fire – called action potential
Action potential properties:
All or nothing response: strong stimulus can trigger more neurons to fire, and to
fire more often, but it does not affect the action potentials strength or speed.
Intensity of an action potential remains the same throughout the length of the
axon
Synapse
• A junction between the axon tip of the sending neuron and the dendrite or cell body of
the receiving neuron. This tiny gap is called the synaptic gap or cleft
• Neurotransmitters and drugs
o Communicate, sends messages
o Neurotransmitters bind to the receptors of the receiving neuron in a key-lock
mechanism
Drugs can be agonists (mimic transmitter) or antagonists (block)
o Serotonin – affects mood, hunger, sleep, and arousal – undersupply leads to
depression
o Dopamine – influences movement, learning, attention, and emotion – excess
leads to schizophreia, stared leads to Parkisos disease
o Acetylcholine (ACh) – enables muscle action, learning, and memory – ACh
produig euros deteriorate ith Alzheiers disease
o Norepinephrine – helps control alertness, mood, and arousal – undersupply can
depress mood
o GABA (gamma-aminobutyric) – major inhibitory neurotransmitter – undersupply
linked to seizures, tremors and insomnia
o Glutamate – major excitatory neurotransmitter; involved in memory -
oversupply can overstimulate brain, causing migraines or seizures
find more resources at oneclass.com
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Document Summary
Neural communication: each neuron receives excitatory and inhibitory signals from many other neurons, when excitatory signal minus the inhibitory signals exceed a minimum intensity (threshold) the neurons fire called action potential. All or nothing response: strong stimulus can trigger more neurons to fire, and to fire more often, but it does not affect the action potentials strength or speed. Intensity of an action potential remains the same throughout the length of the axon. Synapse: a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft: neurotransmitters and drugs, communicate, sends messages, neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism. Parietal lobe receives information about pressure, pain, touch, temperate: plasticity. Plasticity refers to brains ability to modify itself after some types of injuries or illness: lateralization.
