3. BIOLOGICAL BASES OF BEHAVIOR Flashcards
Define: neuron
cells in the nervous system that communicate with one another to perform information processing skills=
Purpose of the cell body
“control center”, coordinates information-processing tasks, keeps the cell alive
Purpose of dendrites
receives information from other neurons and relays to the cell body
Purpose of axon
transmits information to other neurons, muscles, glandsM
Define: myelin sheath
insulating layer of fatty material
Define: glial cell
support cells of the nervous system
Define: synapse
junction between axon of one neuron and dendrites/cell body of another neuron
Define: motor neurons
neurons that carry signals from CNS (spinal cord) to PNS (muscles) to produce movement
Define: interneurons
neurons connecting sensory neurons, motor neurons, other interneurons, “bridge neurons”
Define: sensory neurons
contain specialized dendrites for light, sound, touch, etc.
Functions of glial cells
myelin sheath, supply nourishment to neurons, help remove neurons’ waste products, provide insulation around many axons.
Summarize Hodgkin & Huxley’s discovery about neural impulses
Na+ and K- flow in and out the neurons across the cell membrane at different rates, resulting in a slightly net negative charge in the neuron (more negative ions inside the cell), which causes it to store potential energy like a tiny battery
Define: resting potential
stable, negative charge when the cell is inactive
Approximate resting potential of a neuron
around 70 millivolts
Describe: action potential
very brief shift in neuron’s electrical charge when it is stimulated (Na+ gates open and K- gates close so Na+ rushes in to make the neuron positive)
Define; absolute refractory period
minimum length of time after an action potential fires, during which another action potential cannot begin (1-2 milliseconds)
Define: All-or-None law
either neuron fires or it doesn’t, action potentials are all the same size (size of action potential does not change based on size of stimuli)
Explain how neurons convey information about the strength of a stimulus
variance in rate
Define: synaptic cleft
a microscopic gap between terminal button of one neuron and cell membrane of another (neurons do not directly touch) that signals have to cross to permit communication between neurons
Define: presynaptic neuron
neuron that sends the signal across synaptic cleft
Define: postsynaptic neuron
neuron that receives the signal across the synaptic cleft
Define: neurotransmitter
chemicals that transmit info from one neuron to another triggered by the arrival of an action potential at an axon’s terminal buttons
Define: synaptic vesicles
small sacs where neurotransmitters are stored
Describe the process of a signal crossing the synaptic cleft
When the synaptic vesicle fuses with the presynaptic cell membrane, the neurotransmitters inside are released and diffuse across the synaptic cleft to reach receptor sites on the outside of the postsynaptic cell membrane, where certain neurotransmitters are allowed in
Describe: postsynaptic potential (PSP)
graded (variance in size) voltage change at a receptor site on a postsynaptic cell membrane that occurs when a neurotransmitter and receptor molecule combine
Describe: excitatory PSP
positive voltage shift increasing likelihood that postsynaptic neuron will fire action potentials
Describe: inhibitory PSP
negative voltage shift decreasing likelihood that postsynaptic neuron will fire action potentials
What determines the direction of the voltage shift and nature of PSP
which receptor sites are activated in postsynaptic neuron
Describe: reuptake
neurotransmitters are absorbed from synaptic cleft by the presynaptic membrane
Significance of reuptake
allows synapses to recycle their materials
Define: synaptic pruning
elimination of old or less-active synapses
How many neurons can link with an individual neuron
1000s
Significance of synaptic pruning
major role in formation and strengthening of neural networks crucial to communication in the nervous system
Define: terminal buttons
knoblike structures that branch out from an axon
Define: neurotransmitters
chemicals that transmit information across the synapse to a receiving neuron’s dendrites
List three ways that neurotransmitters respond
reuptake, enzyme deactivation, auto receptor binding
____ and ___ ___ act like a lock-and-key system.
Neurotransmitters, receptor sites
How are neurons interlinked
in complex chains, pathways, circuits, and networks
What shapes our perceptions, thoughts, and actions?
patterns of neural activity in elaborate, widely distributed neural networks
