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Rabu, 12 Juni 2013

Vocabulary of concepts from chapter 34

acetylcholine (ACh)Neurotransmitter; acts on brain, spinal cord, glands, and muscles.
action potentialAbrupt, brief reversal in the resting membrane potential of excitable cells.
autonomic nerveOne of the nerves from central nervous system to smooth muscle, cardiac muscle, and glands of viscera.
axonNeuron's signal-conducting zone.
blood-brain barrierMechanism that controls which solutes enter cerebrospinal fluid.
brainOf most nervous systems, integrating center that receives and processes sensory input and issues coordinated commands for responses by muscles and glands.
brain stemMost ancient nerve tissue in the vertebrate hindbrain, midbrain, and forebrain.
central nervous systemBrain and spinal cord.
cerebellumHindbrain region with reflex centers for maintaining posture and smoothing out limb movements.
cerebral cortexThin surface layer of cerebral hemispheres; receives, integrates, and stores sensory information; coordinates responses.
cerebrumForebrain region that generally deals with olfactory input and motor responses. In mammals, it evolved into the most complex integrating center.
chemical synapseThin cleft between a presynaptic neuron and a postsynaptic cell. Neurotransmitter molecules diffuse across it.
dendriteShort, slender extension from cell body of a neuron; commonly a signal input zone.
drug addictionDependence on a drug, which assumes an ''essential'' biochemical role in the body following habituation and tolerance.
hypothalamusForebrain center of homeostatic control over the internal environment (e.g., salt-water balance, core temperature); influences hunger, thirst, sex, other viscera-related behaviors, and emotions.
interneuronNeuron of brain or spinal cord.
limbic systemIn cerebral hemisphere, centers that govern emotions; has roles in memory.
medulla oblongataHindbrain region with reflex centers for basic tasks (e.g., respiration); coordinates motor responses with complex reflexes (e.g., coughing); influences sleeping.
memoryThe capacity to store and retrieve information about past sensory experience.
motor neuronNeuron that relays signals from brain or spinal cord to muscle or gland cells.
nerveSheathed, cordlike bundle of the axons of sensory neurons, motor neurons, or both.
nerve netSimple nervous system in epidermis of cnidarians and some other invertebrates; a diffuse mesh of simple, branching nerve cells interacts with contractile and sensory cells.
nervous systemIntegrative organ system with nerve cells interacting in signal-conducting and information-processing pathways. Detects and processes stimuli, and elicits responses from effectors (e.g., muscles and glands).
neural tubeThe embryonic and evolutionary forerunner of brain and spinal cord.
neurotransmitterAny of a class of signaling molecules secreted by neurons. It acts on cells next to it, then is rapidly degraded or recycled.
parasympathetic nerveAn autonomic nerve. Its signals slow down overall activities and divert energy to basic tasks; they also help make small adjustments in internal organ activity by acting continually in opposition to sympathetic nerve signals.
peripheral nervous systemAll nerves leading into and out from the spinal cord and brain. Includes ganglia of those nerves.
ponsA hindbrain traffic center for signals between cerebellum and forebrain centers.
positive feedback mechanismHomeostatic control; it initiates a chain of events that intensify change from an original condition, then intensification reverses the change.
reflexStereotyped, simple movement in response to stimuli. In the simplest reflex arcs, it results from sensory neurons synapsing directly on motor neurons.
resting membrane potentialOf a neuron and other excitable cells, a voltage difference across the plasma membrane that holds steady in the absence of outside stimulation.
reticular formationA mesh of interneurons extending from the upper spinal cord, through the brain stem, and into the cerebral cortex; it is a low-level pathway of information flow.
sensory neuronType of neuron that detects a stimulus and relays information about it toward an integrating center (e.g., a brain).
sodium-potassium pumpType of membrane transport protein that, when activated by ATP, selectively transports potassium ions across a membrane against its concentration gradient, and passively allows sodium ions to cross in the opposite direction.
somatic nerveNerve leading from a central nervous system to skeletal muscles.
spinal cordPart of central nervous system, in a canal inside the vertebral column; site of direct reflex connections between sensory and motor neurons; has tracts to and from the brain.
stimulusA specific form of energy (e.g., pressure, light, and heat) that activates a sensory receptor able to detect it.
sympathetic nerveAn autonomic nerve; deals mainly with increasing overall body activities at times of heightened awareness, excitement, or danger; works continually in opposition with parasympathetic nerves to make minor adjustments in internal organ activities.
synaptic integrationMoment-by-moment combining of all excitatory and inhibitory signals arriving at the trigger zone of a neuron or some other excitable cell.
thalamusA forebrain region that is a coordinating center for sensory input and a relay station for signals to the cerebrum.

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