| Term | Definition |
|---|
| central nervous system | brain and the spinal cord |
| peripheral nervous system | afferent/sensory neurons and efferent neurons |
| somatic motor division | control skeletal muscles |
| autonomic division | controls smooth and cardiac muscles, exocrine glands, some endocrine glands, and some type of adipose tissue |
| enteric nervous system | network of neurons in the walls of the digestive tract |
| dendrite | long processes that extend outward from the cell body; receives incoming signals |
| axon | long processes that extend outward from the cell body; carry outgoing information |
| afferent neuron | a neuron that transmits sensory information to the central nervous system; sensory neuron |
| efferent neuron | a peripheral neuron that carries signals from the central nervous system to the target cells |
| pseudounipolar | axon and dendrites fuse during development to create one long process |
| bipolar | single axon and single dendrite |
| anaxonic | lacking an identifiable axon |
| interneurons | neurons that lie entirely within the CNS |
| varicosities | enlarged regions along the axon; in the autonomic division |
| nerve | cordlike fiber; axons of peripheral neurons bundled together with connective tissues |
| sensory nerve | nerve that carries only afferent signals |
| motor nerve | nerve that carries only efferent signals |
| mixed nerve | nerve that carries signals in both afferent and efferent directions |
| soma | cell body; nucleus and all organelles |
| dendritic spine | thin spikes, mushroom-shaped knobs; expands dendrite's surface area |
| axon hillock | where the axon originates from a specialized region of the cell body |
| collateral | branch of an axon |
| axon terminal | a swelling that a collateral ends in |
| synapse | where an axon terminal meets its target cell |
| presynaptic cell | neuron that delivers signal to synapse |
| postsynaptic cell | neuron that receives signal from synapse |
| synaptic cleft | narrow space between two cells forming a synapse |
| axonal transport | process by which proteins are moved down an axon |
| slow axonal transport | type of transport using axoplasmic flow; used for components that aren't consumed rapidly by the cell (enzymes, cytoskeleton proteins) |
| axoplasmic flow | cytoplasmic flow |
| fast axonal transport | a type of transport that moves organelles at rates of up to 400 mm a day; uses stationary microtubules as tracks along which transported vesicles and mitochondria walk; forward/anterograde transport moves synaptic and secretory vesicles and mitochondria from cell body to axon terminal' back/retrograde transport returns old cellular components from axon terminal to cell body for recycling |
| glial cell | cells that provide physical and biochem support to neurons, give neurons structural stability |
| Schwann cell | in the PNS; support and insulate axons by forming myelin |
| oligodendrocyte | in the CNS; support and insulate axons by forming myelin |
| myelin | substance composed of multiple concentric layers of phospholipid membrane |
| node of Ranvier | gap between the myelin-insulted area, a tiny region of axon membrane remains in direct contact with the extracellular fluid |
| satellite cell | nonmyelinating Schwann cell; form supportive capsules around nerve cell bodies located in ganglia |
| ganglion | cluster of nerve cell bodies found outside CNS; knots or swellings along a nerve |
| nucleus | equivalent structure of a ganglion; inside the CNS |
| microglia | specialized immune cells that reside permanently in the CNS; remove damaged cells and foreign invaders |
| astrocyte | highly branched cell that contact neurons and blood vessels and may transfer nutrients between the two; maintain homeostasis in ECF around CNS neurons by taking up K+ and neurotransmitters |
| ependymal cell | specialized cell that creates a selectively permeable epithelial layer/ependyma, that separates the fluid compartments of the CNS |
| neural stem cell | immature cell that can differentiate into a neuron and glial cell |
| mechanically gated ion channel | an ion channel found in sensory neurons that opens in response to physical forces such as pressure or stretch |
| chemically gated ion channel | an ion channel in most neurons; responds to a variety of ligands such as extracellular neurotransmitters and neuromodulators or intracellular signal molecules |
| voltage-gated ion channel | an ion channel that responds to changes in the cell's membrane potential; it plays an important role in the initiation and conduction of electrical signals |
| threshold voltage | minimum stimulus |
| activation | channel opening |
| inactivation | channel closing |
| current | flow of electrical charge carried by an ion |
| graded potential | a variable-strength signal that travels over short distances and loses strength as it moves through a cell |
| action potential | a large, constant-strength depolarization that can travel for long distances through a neuron without losing strength |
| local current flow | wave of depolarization that moves through the cell |
| trigger zone | the axon hillock and the very first part of the axon (initial segment); integrating center of the neuron; contains a lot of voltage-gated Na+ channels in its membraneexi |
| initial segment | the very first part of the axon |
| excitatory | a depolarizing graded potential |
| inhibitory | a hyperpolarizing graded potential |
| excitability | ability of a neuron to respond rapidly to a stimulus and fire an action potential |
| all-or-none | action potentials either occur as a maximal depolarization or do not occur at all |
| activation gate | sodium channel gate that opens to initiate an action potential |
| inactivation gate | the slow gate of the Na+ channel that closes to stop ion flow |
| relative refractory period | a period of time immediately following an action potential during which a higher-than-normal graded potential is required to start another action potential |
| absolute refractory period | a period of time around 2 msec during which a second action potential cannot be triggered no matter how large the stimulus is |
| conduction | the high-speed movement of an action potential through the axon |
| saltatory conduction | the jump of the action potential from node to node |
| hyperkalemia | an increase in blood [K+] that shifts the resting membrane potential of a neuron closer to threshold |
| hypokalemia | a decrease in blood [K+] causes hyperpolarization of membrane potential of cells |
Combine with other sets
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