| A | B |
|---|
| Briefly describe conditions inside a resting neuron. | High K+, low Na+, net negative charge |
| Because the plasma membrane of a resting neuron has a ___ charge to the inside edge and a ___ charge to the outside edge, the membrane is said to be ____. | Negative / positive / polarized |
| The resting ____ ____ of a neuron is due to the separation of charges across the plasma membrane. | Membrane potential |
| Ion channels in a neuron's plasma membrane that are always open are called ___ channels. | Leakage |
| Ion channels that open and close under certain conditions are called ____ channels. | Gated |
| Ion channels that open in response to a direct change in the membrane potential are called ___ - ____ channels. | Voltage-gated |
| Ion channels that open and close in response to specific chemicals are called ____ - ___ channels. | Ligand-gated |
| When a neuron depolarizes, the charge inside changes from ___ to ___. | Negative to positve |
| The ions that enter a neuron to bring about depolarization are ____ ions. | Na+ |
| As soon as depolarization has occurred, the neuron immediately becomes ____ inside again due to opening of ___ channels and movement of ___ out of the cell. | Negative / K+ /K+ ions |
| When a depolarized neuron becomes negative inside again, this is called ____. | Repolarization |
| To complete the process of repolarization of a neuron, the ______ pump returns ions to where they belong. | Na+ / K+ |
| A neuron that is more negatively charged inside than usual is said to be ____. | Hyperpolarized |
| Immediately following the generation of a nerve action potential, there is a time when the neuron cannot generate another action potential. This is called the ____ period. | Refractory |
| True or false-if a stimulus of at least threshold strength is applied to a neuron, the strength of the action potential that results is proportional to the strength of the stimulus. | False--remember the all-or-none principal |
| We are able to detect differences in the strength of stimuli due to: | Frequency of stimulus and number of sensory neurons involved |
| _____ conduction of impulses is the type that occurs down unmyelinated axons. | Continuous |
| ____ conduction occurs down myelinated axons. | Saltatory |
| Two characteristics of saltatory conduction are that it is ____ and requires less ____. | Faster / energy |
| List the 3 factors that influence speed of nerve impulse conduction. | Presence or absence of myelin, diameter of fiber, and temperature. |
| List some characteristics of axons known as A fibers. | Largest diameter, briefest refractory period, myelinated, speed up to 300 feeet / second. |
| A fibers are found in what type of locations? | Large sensory nerves and motor nerves to skeletal muscle where split-second reactions may mean survival. |
| List some characteristics of axons known as B fibers. | Medium diameter, medium refractory period, myelinated, speed 30 - 40 feet / second. |
| List some characteristics of axons known as C fibers. | Smallest diameter, longest refractory period, unmyelinated, speed 1.5 feet / second. |
| Synapses that operate without a neurotransmitter involved are called ___ synapses. | Electrical |
| In an electrical synapse, action potentials spread from cell to cell through ____ junctions. | Gap |
| List some benefits of electrical synapses. | Very fast conduction, 2-way conduction, activation of large numbers of muscle fibers or neurons all at once. |
| Most synapses require a neurotransmitter and are called ___ synapses. | Chemical |
| At a chemical synapse, depolarization of the synaptic end bulb opens both ___ and ___ ion channels. | Na+ and Ca 2+ |
| At a chemical synapse, synaptic ____ release neurotransmitter by ____. | Vesicles / exocytosis |
| Excitatory neurotransmitters cause the opening of ___ channels in the postsynaptic neuron. | Na+ |
| Inhibitory neurotransmitters cause the opening of either ___ or ___ channels in the postsynaptic neuron. | K+ or Cl - |
| Inhibitory neurotransmitters cause the charge in the postsynaptic neuron to become more ___ than usual, which is called ____. | Negative / hyperpolarization |
| Neurotransmitters are removed from the synaptic cleft in what 3 ways? | Diffusion, breakdown by a specific enzyme, or uptake into surrounding cells. |
| List the 5 groups of small molecule neurotransmitters. | Acetylcholine, amino acids, biogenic amines, ATP, gases. |
| List 2 excitatory amino acid neurotransmitters. | Glutamate & aspartate |
| List 2 inhibitory amino acid neurotransmitters. | GABA & glycine |
| List the biogenic amine neurotransmitters. | Epinephrine, norepinephrine, dopamine, serotonin. |
| When the neurons that produce dopamine are damaged or destroyed, ____ disease occurs. | Parkinson's |
| The only positively identified gaseous neurotransmitter is ___. | Nitric oxide |
| The group of neurotransmitters made up of larger molecules is called ____. | Neuropeptides |
| The neuropeptide that increases sensitivity to pain is ___. | Substance P |
| Name the 3 opiate peptides. | Enkephalins, endorphins, dynorphins. |
| Alkalosis leads to increased ____ of neurons. | Excitability |
| Acidosis leads to ____ of neurons. | Depression |
| ____ circuits tend to have widespread effects. | Diverging |
| When a number of presynaptic neurons synapse with a single postsynaptic neuron, this would be a ___ circuit. | Converging |
| Axons of the ___ nervous system have at least the possibility of regrowth following injury. | Peripheral |
| ____ nervous system axons do not regrow following injury. | Central |
| The neurolemma of a PNS axon forms a ____ tube that directs and encourages regrowth of an injured axon. | Regeneration |
