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NEURON FUNCTION TEST PREP
COURSEWORK SCRIPT STUDY SHEET 2026
GRADED A+.
⫸ neurons. Answer: Specialized cells in the nervous system that communicate using chemical and electrical signals. Many, but not all, _________ are excitable cells that generate action potentials. ⫸ motor neuron. Answer: A neuron that transmits signals from the central nervous system to skeletal muscles. ⫸ dendrites. Answer: The branching extensions of a neuronal cell body that carry signals toward the cell body. ⫸ cell body. Answer: Contains the nucleus. ⫸ axon hillock. Answer: The junction between the cell body and axon of a neuron. In many neurons, the _________ is the site of action potential initiation, acting as the trigger zone for the neuron. ⫸ axon. Answer: A projection of the cell body of a neuron that is involved in carrying information, usually in the form of action potentials, from the cell body to the _________ terminal.
⫸ action potential. Answer: A relatively large-amplitude, rapid change in the membrane potential of an excitable cell as a result of the opening and closing of voltage-gated ion channels; involved in transmitting signals across long distances in the nervous system. ⫸ myelin sheath. Answer: The insulating wrappings of vertebrate axons that are composed of multiple layers of glial cell plasma membrane. Invertebrate axons have analogous wrappings, but they are not generally termed a _________. ⫸ axon terminal. Answer: The distal end of an axon that forms a synapse with an effector cell or neuron. ⫸ synapse. Answer: The junction between a neuron and another neuron or effector cell; consists of a presynaptic cell, the synaptic cleft, and a postsynaptic cell ⫸ depolarization. Answer: A change in the membrane potential of a cell from its normally negative resting membrane potential to a more positive value; a relative increase in the positive charge on the inside of the cell membrane. ⫸ hyperpolarization. Answer: A change in the membrane potential of a cell from its normally negative resting membrane potential to a more negative value; a relative increase in the negative charge on the inside of the cell membrane.
⫸ depolarization. Answer: A change in the membrane potential of a cell from its normally negative resting membrane potential to a more positive value; a relative increase in the positive charge on the inside of the cell membrane. ⫸ repolarization. Answer: A return of the membrane potential of a cell toward the resting membrane potential following a depolarization or hyperpolarization. ⫸ after-hyperpolarization. Answer: A prolonged hyperpolarization following an action potential. ⫸ absolute refractory period. Answer: The period during and immediately following an action potential in which an excitable cell cannot generate another action potential, no matter how strong the stimulus. ⫸ relative refractory period. Answer: A period immediately following the absolute refractory period in which an excitable cell will generate an action potential only if exposed to a suprathreshold (unusually large) stimulus. ⫸ voltage-gated ion channel. Answer: A membrane protein containing an aqueous pore that can be opened in response to changes in the membrane potential.
⫸ activation gate. Answer: One of the two gates that open and close voltage-gated sodium channels. Allows Na+ to move across the membrane. ⫸ inactivation gate. Answer: One of the two gates that open and close voltage-gated sodium channels. When closed, no more Na+ can enter the cell. ⫸ myelin. Answer: Insulating layer than wraps the axons of vertebrate motor neurons. ⫸ Schwann cell. Answer: A type of glial cell in the vertebrates that forms the myelin sheath around axons in the peripheral nervous system. ⫸ glial cells. Answer: A group of several types of cells that provide structural and metabolic support to neurons. ⫸ nodes of Ranvier. Answer: A gap of exposed axonal membrane between two regions of myelin sheath. ⫸ internode. Answer: The region of axonal membrane that is covered with the myelin sheath. ⫸ saltatory conduction. Answer: The mode of conduction of action potentials in myelinated axons in which action potentials appear to jump from one node of Ranvier to the next.
⫸ sensory neurons. Answer: A neuron that conveys sensory information from the periphery to the central nervous system ⫸ interneuron. Answer: A neuron that makes synaptic connections between other neurons. ⫸ efferent neurons. Answer: A neuron that conducts impulses from an integrating center to an effector. ⫸ multipolar neurons. Answer: Neurons with many processes leading from the cell body; most of these processes are dendrites, but one may be an axon. ⫸ bipolar neuron. Answer: A neuron with two main processes leading from the cell body, one of which conveys signals toward the cell body, and one of which conveys signals away from the cell body. ⫸ unipolar neuron. Answer: A neuron with one process leading from the cell body; this process generally splits into two branches, one conveying information toward the cell body and one conveying information away from the cell body. ⫸ oligodendrocyte. Answer: A vertebrate glial cell that forms the myelin sheath of a neuron in the central nervous system. ⫸ astrocytes. Answer: Vertebrate glial cells that help to support and regulate the action of neurons in the central nervous system.
⫸ microglia. Answer: One of the glial cells of the vertebrate central nervous system. ⫸ ependymal cells. Answer: Cells that line the ventricles of the brain. ⫸ gliocytes. Answer: A type of invertebrate glial cell. ⫸ giant axons. Answer: Unusually large-diameter axons that are present in some invertebrates and vertebrates. ⫸ cable properties. Answer: The electrical properties of axons. ⫸ electrical synapse. Answer: A junction between neurons in which the signal is transmitted as an electrical charge rather than via a neurotransmitter ⫸ chemical synapse. Answer: A junction between a neuron and another cell in which the signal is transmitted across the synapse in the form of a neurotransmitter. ⫸ axon varicosity. Answer: A type of synapse in which the presynaptic cell releases neurotransmitter at a series of swellings along the axon.
⫸ adrenergic receptors. Answer: Receptors for the catecholamines norepinephrine and epinephrine. ⫸ synaptic facilitation. Answer: An increase in neurotransmitter release in response to repeated action potentials. ⫸ synaptic depression. Answer: A decrease in neurotransmitter release in response to repeated action potentials. ⫸ post-tetanic potentiation (PTP). Answer: A phenomenon in which a postsynaptic cell will respond with an unusually large change in membrane potential for several minutes following repeated action potentials in the presynaptic cell. ⫸
