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- a nerve cell
- the basic building block of the nervous system
X Biological Psychology
a branch of psychology concerned with the links between biology and behavior.
X Sensory Neurons
neurons that carry incoming information from the sensory receptors to the brain and spinal cord.
X Motor Neurons
- neurons that carry outgoing information from the brain
- and spinal cord to the muscles and glands
- neurons within the brain and spinal cord that
- communicate internally
- and intervene between the sensory inputs and motor outputs.
- the bushy, branching extensions of a neuron
- that receive messages and
- conduct impulses toward the cell body.
- the extension of a neuron
- ending in branching terminal fibers
- through which messages pass to other neurons or to muscles or glands
X Myelin Sheath
- a layer of fatty tissue segmentally encasing the fibers of many neurons
- enables vastly greater transmission speed of neural impulses as the impulses hop from one node to the next
X Action Potential
- a neural impulse
- a brief electrical charge that travels down the axon.
- The voltage shifts from -70mV to +40mV for about one millisecond when ion channels open to allow positively charged sodium ions to rush into the axon from the fluid outside the cell.
the level of stimulation required to trigger a neural impulse
H Synapse or Synaptic space
fluid-filled tiny gap between the terminal button of one neuron and the membrane of the next neuron
X Synaptic Gap/ Synaptic cleft
The tiny gap in between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
- chemical messengers that cross the synaptic gaps between neurons.
- when released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
- "morphine within"
- natural, opiatelike neurotransmitters linked to pain control and to pleasure
- Neuromodulators not neuro transmitters
- "runner's high" secretion of dopamine which mute signals of pain
- High level = insensitivity to pain
- Low level = hypersensitivity to pain or immune problems
X Acetylcholine (ACh)
- Enables muscle action, learning, and memory
- Connected to Alzheimer's disease- ACh-producing neurons deteriorate
- absent of chemical = paralysis
- high levels of chemical = violent muscle contractions
- involves motivation, voluntary movement, emotion, and attention & learning
- Excess dopamine receptor activity is linked to Schizophrenia.
- Starved of dopamine, the brain produces the tremors and decreased mobility of Parkison's disease.
- Affects mood, hunger, sleep, and arousal
- Undersupply linked to depression
- helps control alertness and arousal
- undersupply can depress mood
- low level = ADD, depression
- High level = panic disorder
X GABA (gamma-aminobutyric acid)
- reduces neural activity in brain structures that trigger emotional arousal. (including the amygdala).
- Low amount: Anxiety and Huntington's disorder
- A major excitatory neurotransmitter involved in memory
- oversupply can overstimulate brain, producing migraines or seizures
- MSG = monosodium glutamate
large proteins embedded in the receiving cell's membrane
H Ion channels
pores in the cell's membrane that allow certain substances in the body, fluid, to enter the cell while refusing or limiting the passage of other substances
the cell body contains the biochemical structures necessary to keep the neuron alive
H Axon Hillock
region of the soma that connects the soma to the axon
Action potential threshold
H Terminal Buttons
- Located in a cluster at the end of the axon
- (axon chemicals)
- which secrete chemicals called neurotransmitters
H Resting Potential
- due to the distribution of positively and negatively charged ions inside and outside the neuron.
- Voltage across the cell membrane is -70mV
- ( the inside is more negative by about 70mv)
H Post-Synaptic Potential (PSP)
- is a change in voltage in the Soma
- as a result of ions traveling in or out of the soma
- after a neurotransmitter binds to a receptor
H Excitatory Post Synaptic Potentials
- are caused when an excitatory neurotransmitter binds to a receptor thereby
- opening sodium ion channels so that positibely charged sodium ions enter the cell
- causing the voltage in the soma to become +50mV
H Inhibitory Post Synaptic Potential
- are caused when an inhibitory neurotransmitter binds to a receptor
- thereby opening potassium channels so that positively charged potassium ions exit the cell
- or opening chloride channels so that negatively charged chloride ions enter the cell
- causing the voltage in the soma to become +40mV
H Spatial Summation
the EPSP becomes very strong as a result of excitatory neurotansmitters binding at different receptor sites thus voltage at the axon hillock reaches threshold.
H Temporal Summation
the EPSP becomes very strong as a result of excitatory Neurotransmitters binding in rapid succession at a single recepter site thus the voltage at the axon hillock reaches threshold.
Electrical Post Synaptic Potential
H All-or-none law
- action potentials occur at a uniform and mazimum intensity
- (from -70mV to +40mV in an instant)
- or they do not occur at all
the voltage and distribution of ions in and outside the axon must be returned to that of resting potential
H Absolute Refractory Period
- the minimum length of time after an action potential
- during which the axon membrane is not excitable
- and cannot discharge another impulse
- the ability of a neurotansmitter to continue to excite or inhibit the post-synaptic neuron is ended when either
- enzymes in the synapse break the neurotransmitter down into its chemical components, or
- the neuro transmitter is taken back up into the pre-synaptic cell (reuptake).
H Chemical Imbalance
the level of activity in cells that produce or receive a certain neurotransmitter is abnormally high or low
drugs that block the action of neurotransmitters
drugs that mimic the action of neurotransmitters
H Parkinson's Disease
- can occur when levels of dopamine are too low in the basal ganglia.
- Symptoms include: Motor trmors, rigid muscles
can occur when levels of dopamine are too low in the limbic system
- includes psychotic delusions and hallucinations
- due to too high levels of dopamine activity in the frontal lobe of the cerebral cortex
H Antipsychotic drugs
- reduce dopamine to relieve psychotic symptoms of schizophreniz,
- but can have a side effect causing motor tremors and depression.
- mutes signals of pain from the body
- and produces a "high" because it travels into the brain and binds to neurons with endorphin receptors
- mimics endorphins and is therefore an endorphin agonist
- loss of brain cells
- deterioration of neurons that produce ACh
- memory and thinking suffer
the voltage moves from -70mV closer and closer to +50mV as sodium enters the cell & the strength of EPSP increases.