PSYA01H3 Chapter Notes -Sympathetic Nervous System, Carl Wernicke, Electric Shock

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3 Feb 2013
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Neuroscience and behaviour (chapter 3)
Neurons: the origin of behaviour
- Neurons: cells in the nervous system that communicate with one another to perform
information processing tasks
The discovery of how neurons work
- Santiago ramon y cajal, new technique for staining neurons in the brain
- Information processing units of the brain and that even though he saw gaps between neurons
they had to communicate in some way
Components of the neuron
- Cell body: the part of the neuron that coordinates information processing tasks and keeps the
cell alive (soma) protein synthesis, energy production, metabolism take place here
- Nucleus, houses chromosomes that contain your dna or the genetic blueprint of who you are
- Dendrites: receives information from other neurons and relays it to the cell body
- Axon: transmits information to other neurons, muscles, or glands
- Myelin sheath: an insulating layer of fatty material
- Glial cells: support cells found in the nervous system, digest parts of dead neurons, provide
physical and nutritional support for neurons
- Myelin performs this same function for an axon
- Dennyelinating diseases
- Synapse: the junction or region between the axon of one neuron and the dendrites or cell body
of another
Major types of neurons
- Sensory neurons: neurons that receive information from the external world and convey this
information to the brain via the spinal cord
- Motor neurons: carry signals from the spinal cord to the muscles to produce movement, have
long axons that can stretch to muscles at our extremities
- Interneurons: connect sensory neurons, motor neurons, other interneurons, carry information
from sensory neurons into the nervous system to motor neurons, and still others perform a
variety of information processing functions within the nervous system
Neurons specialized by location
- Purkinje cells are a type of interneuron that carries information from the cerebellum to the rest
of the brain and spinal cord
- Pyramidal cells, found in the cerebral cortex have a triangular cell body and a single long
dendrite among many smaller dendrites
- Bipolar cells
The electrochemical actions of neurons: information processing
- Conduction and transmission
- Resting potential: the difference in electrical charge between the inside and outside of a
neuron’s cell membrane
- Arise from the difference in concentrations of ions inside and outside the neuron’s cell
membrane
- Negative
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The action potential: sending signals across the neuron
- Action potential: an electric signal that is conducted along the length of a neuron’s axon to the
synapse
- Electric shock reaches a certain level. Threshold
- Shock below threshold tiny signals
- All or none
- There is change in the state of the axon’s membrane channels
- Refractory period: the time following an action potential during which a new action potential
cannot be initiated
- Myelin sheath
- Nodes of ranvier
Chemical signaling: transmission between neurons
- Terminal buttons: knoblike structures that branch out from an axon
- Neurotransmitters: chemicals that transmit information across the synapse to a receiving
neuron’s dendrites
- Receptors: parts of the cell membrane that receive the neurotransmitter and initiate or prevent
a new electric signal
- Presynaptic neuron
- Postsynatptic neuron
- Synaptic neuron
- Reuptake occurs when neurotransmitters are reabsorbed by the terminal buttons of the
presynaptic neuron’s axon
- Enzyme deactivation
- Neurotransmitters can bind to the receptor sites called autoreceptors on the presynaptic
neurons
- Autoreceptors detect how much of a neurotransmitter has been released into a synapse and
signal the neuron to stop releasing the neurotransmitter when an excess is present
Types and functions of neurotransmitters
- Acetylcholine (ach): a neurotransmitter involved in a number of functions, including voluntary
motor control
- Dopamine: a neurotransmitter that regulates motor behaviour, motivation, pleasure, and
emotional arousal
- Glutamate: a major excitatory neurotransmitter involved in information transmission
throughout the brain
- Gaba(gamma aminobutyric acid): the primary inhibitory neurotransmitter in the brain
- Norepinephrine: a neurotransmitter that influences mood and arousal
- Serotonin: a neurotransmitter that is involved in the regulation of sleep and wakefulness, eating
, and aggressive behaviour
- Endorphins: chemicals that act within the pain pathways and emotion centers of the brain
How drugs mimic neurotransmitters
- Agonists: drugs that increase the action of a neurotransmitter
- Antagonists: drugs that block the function of a neurotransmitter
- Methamphetamine affects pathways for dopamine, serotonin, and norepinephrine at the
neuron’s synapses, making it difficult to interpret exactly how it works
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