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Bio117 CH45
Freeman Vocab Chapter 45: Electrical Signals in Animals
| Question | Answer |
|---|---|
| acetylcholine | A neurotransmitter, released by nerve cells at neuromuscular junctions, that triggers contraction of muscle cells. Also used as a neurotransmitter between neurons. |
| action potential | A rapid, temporary change in electrical potential across a membrane, from negative to positive and back to negative. Occurs in cells, such as neurons and muscle cells, that have an excitable membrane. |
| afferent division | The part of the nervous system, consisting mainly of sensory neurons, that transmits information about the internal and external environment to the central nervous system. Compare with efferent division. |
| autonomic nervous system | The part of the peripheral nervous system that controls internal organs and involuntary processes, such as stomach contraction, hormone release, and heart rate. Includes parasympathetic and sympathetic nerves. Compare with somatic nervous system. |
| axon | A long projection of a neuron that can propagate an action potential and transmit it to another neuron. |
| axon hillock | The site in a neuron where an axon joins the cell body and where action potentials are first triggered. |
| brain stem | The most posterior portion of the vertebrate brain, connecting to the spinal cord and responsible for autonomic body functions such as heart rate, respiration, and digestion. |
| cell body | The part of a neuron that contains the nucleus and where incoming signals are integrated. Also called the soma. |
| central nervous system (CNS) | The brain and spinal cord of vertebrate animals. Compare with peripheral nervous system (PNS). |
| cerebellum | Posterior section of the vertebrate brain that is involved in coordination of complex muscle movements, such as those required for locomotion and maintaining balance. |
| cerebrum | The most anterior section of the vertebrate brain. Divided into left and right hemispheres and four lobes: parietal lobe, involved in complex decision making (in humans); occipital lobe, receives and interprets visual information; parietal lobe, involved |
| corpus callosum | The brain and spinal cord of vertebrate animals. Compare with peripheral nervous system (PNS). |
| dendrite | A short extension from a neuron's cell body that receives signals from other neurons. |
| depolarization | Change in membrane potential from its resting negative state to a less negative or a positive state; a normal phase in an action potential. Compare with hyperpolarization. |
| diencephalon | The part of the mammalian brain that relays sensory information to the cerebellum and functions in maintaining homeostasis. |
| efferent division | The part of the nervous system, consisting primarily of motor neurons, that carries commands from the central nervous system to the body. |
| electric current | A flow of electrical charge past a point. Also called current. |
| electrical potential | Potential energy created by a separation of electric charges between two points. Also called voltage. |
| electrochemical gradient | The combined effect of an ion's concentration gradient and electrical (charge) gradient across a membrane that affects the diffusion of ions across the membrane. |
| equilibrium potential (Eion) | The membrane potential at which there is no net movement of a particular ion into or out of a cell. |
| excitable membrane | A plasma membrane that is capable of generating an action potential. Neurons, muscle cells, and some other cells have excitable membranes. |
| excitatory postsynaptic potential (EPSP) | A change in membrane potential, usually depolarization, at a neuron dendrite that makes an action potential more likely. |
| frontal lobe | In the vertebrate brain, one of the four major areas in the cerebrum. |
| hyperpolarization | Change in membrane potential from its resting negative state to an even more negative state; a normal phase in an action potential. Compare with depolarization. |
| inhibitory postsynaptic potential (IPSP) | A change in membrane potential, usually hyperpolarization, at a neuron dendrite that makes an action potential less likely. |
| interneuron | A neuron that passes signals from one neuron to another. Compare with motor neuron and sensory neuron. |
| ion channel | A type of channel protein that allows certain ions to diffuse across a plasma membrane down an electochemical gradient. |
| leak channel | Potassium channel that allows potassium ions to leak out of a neuron in its resting state. |
| learning | Potassium channel that allows potassium ions to leak out of a neuron in its resting state. |
| ligand | Any molecule that binds to a specific site on a receptor molecule. |
| ligand gated channel | An ion channel that opens or closes in response to binding by a certain molecule. Compare with voltage-gated channel. |
| membrane potential | A difference in electric charge across a cell membrane; a form of potential energy. Also called membrane voltage. |
| memory | Retention of learned information. |
| millivolt | A unit of voltage equal to 1/1000 of a volt. |
| motor neuron | A nerve cell that carries signals from the central nervous system (brain and spinal cord) to an effector, such as a muscle or gland. Compare with interneuron and sensory neuron. |
| multiple sclerosis (MS) | A human autoimmune disease caused by the immune system attacking the myelin sheaths that insulate nerve axons. |
| myelin sheath | Multiple layers of myelin, derived from the cell membranes of certain glial cells, that is wrapped around the axon of a neuron, providing electrical insulation. |
| nerve | A long, tough strand of nervous tissue typically containing thousands of axons wrapped in connective tissue; carries impulses between the central nervous system and some other part of the body. |
| nerve net | A nervous system in which neurons are diffuse instead of being clustered into large masses or tracts. |
| neuron | A cell that is specialized for the transmission of nerve impulses. Typically has dendrites, a cell body, and a long axon that forms synapses with other neurons. Also called nerve cell. |
| neurotoxin | Any substance that specifically destroys or blocks the normal functioning of neurons. |
| neurotransmitter | A molecule that transmits electrical signals from one neuron to another or from a neuron to a muscle or gland. Includes acetylcholine, dopamine, serotonin, and norepinephrine. |
| nodes of ranvier | One of the periodic unmyelinated sections of a neuron's axon at which an action potential can be regenerated. |
| occipital lobe | In the vertebrate brain, one of the four major areas in the cerebrum. |
| oligodendrocyte | A type of glial cell that wraps around axons of some neurons in the central nervous system, forming a myelin sheath that provides electrical insulation. Compare with Schwann cell. |
| parasympathetic nervous system | The part of the autonomic nervous system that stimulates functions for conserving or restoring energy, such as reduced heart rate and increased digestion. Compare with sympathetic nervous system. |
| parietal lobe | In the vertebrate brain, one of the four major areas in the cerebrum. |
| patch clamping | A technique for studying the electrical currents that flow through individual ion channels by sucking a tiny patch of membrane to the hollow tip of a microelectrode. |
| peripheral nervous system (PNS) | All the components of the nervous system that are outside the central nervous system (the brain and spinal cord). Includes the somatic nervous system and the autonomic nervous system. |
| positive feedback | A physiological mechanism in which a change in some variable stimulates a response that increases the change. Relatively rare in organisms but is important in generation of the action potential. |
| postsynaptic neuron | A neuron that receives signals, usually via neurotransmitters, from another neuron at a synapse. Muscle and gland cells also may receive signals from presynaptic neurons. |
| presynaptic neuron | A neuron that transmits signals, usually by releasing neurotransmitters, to another neuron or to an effector cell at a synapse. |
| refractory | No longer responding to stimuli that previously elicited a response. For example, the tendency of voltage-gated sodium channels to remain closed immediately after an action potential. |
| repolarization | Return to a normal membrane potential after it has changed; a normal phase in an action potential. |
| resting potential | The membrane potential of a cell in its resting, or normal, state. |
| Schwann cell | A type of glial cell that wraps around axons of some neurons outside the brain and spinal cord, forming a myelin sheath that provides electrical insulation. Compare with oligodendrocyte. |
| second messenger | A nonprotein signaling molecule produced or activated inside a cell in response to stimulation at the cell surface. Commonly used to relay the message of a hormone or other extracellular signaling molecule. |
| sensory neuron | A nerve cell that carries signals from sensory receptors to the central nervous system. Compare with interneuron and motor neuron. |
| serotonin | A neurotransmitter involved in many brain functions, including sleep, pleasure, and mood. |
| soma | The part of a neuron that contains the nucleus and where incoming signals are integrated. Also called the soma. |
| somatic nervous system | The part of the peripheral nervous system (outside the brain and spinal cord) that controls skeletal muscles and is under voluntary control. Compare with autonomic nervous system. |
| summation | The additive effect of different postsynaptic potentials at a nerve or muscle cell, such that several subthreshold stimulations can cause an action potential. |
| sympathetic nervous system | The part of the peripheral nervous system (outside the brain and spinal cord) that controls skeletal muscles and is under voluntary control. Compare with autonomic nervous system. |
| synapse | The interface between two neurons or between a neuron and an effector cell. |
| synaptic cleft | The space between two communicating nerve cells (or between a neuron and effector cell) at a synapse, across which neurotransmitters diffuse. |
| synaptic plasticity | Long-term changes in the responsiveness or physical structure of a synapse that can occur after particular stimulation patterns. Thought to be the basis of learning and memory. |
| synaptic vesicle | A small neurotransmitter-containing vesicle at the end of an axon that releases neurotransmitter into the synaptic cleft by exocytosis. |
| temporal lobe | In the vertebrate brain, one of the four major areas in the cerebrum. |
| threshold potential | The membrane potential that will trigger an action potential in a neuron or other excitable cell. Also called simply threshold. |
| volt (V) | A unit of electrical potential (voltage). |
| voltage | Potential energy created by a separation of electric charges between two points. Also called electrical potential. |
| voltage clamping | A technique for imposing a constant membrane potential on a cell. Widely used to investigate ion channels. |
| voltage-gated ion channel | An ion channel that opens or closes in response to changes in membrane voltage. Compare with ligand-gated channel. |
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