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Chapter 2 Vocabulary

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Neuron
A nerve cell; the basic budilgin block of the nervous sytem
Snesory Neurons
Neurons that carry incoming information from teh sensory receptors to the brain and spinal cord
Motor Neurons
Neurons tha carry outgoing information fromt he brain and spinal cord to the muscles and galnds
Interneurons
Neurons within the brain and spinal cord that communicate internally and inetervene between the sensory inpyuts and motor outputs
Dendrite
The busy, brabnching extensions of a neuron that recieve messages and conduct impulses toward the cell body
Axon
The extension of a neuron, ending in branching terminal fibers thorugh which emssages pass to other neurons tr to muslces or glands
Myelin sheath
A layer of fatty tissue segmentally encasing the fibers of many neurons enables vastly greater tranjsmission speed of neural impulses as the impuls hops from one node to the next
Action potential
A neural impuls; a bfried electrical charage that travels down an axon
Cell body
The cells life support center
Neural impulse
Electrical signal traveling down the axon
Terminal branches of the axon
Form junctions with other cells
Threshold
The level of stimulation required to trigger a neural impulse
Synapse
The junction between the axon tip of the sending neuron and the dendrite or cell body of the recieving neuron. TH etiny gap at this junction is called the synaptic gap or synaptic cleft.
Neurotransmitters
Chemical messengers that cross the synaptic gaps between tneurons. When released by teh sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the reicieving neuron, thereby influencing whether that neuron will generate a neural impulse
Reuptake
A neurotransmitters reabsorption by the sending neuron
Endorphins
Natural, opioatelike neurotransmitters linked to pain control and to pleasure
Nervous system
The body's speedy, electrochemical communication netwokr, consisting of all hte nerve cells of the peripheral and central nervous systems
Central nervous system (CNS)
The brain and spinal cord
Peripheral nervous sytem (PNS)
The sensory and motoer neruons that connect the central
Nerves
Bundled axons that form nerual cables connectin gthe central nervous syutem with muslces, glands, and sense organs
Somatic nervous system
The division of the peripheral nervous system that controls the body's skeletal muscles
Autonomic nervous sytem
The part of the peripheral nervous system that controls the gland and the muscles of the internal organs. Its sympathetic division arouses; its parasympathetic division calms
Sympathetic nervous system
The division of the authonomic nervous system that arouses the body, mobilizing its energy in stressful situations
Parasympathetic nervous system
Th edivision of the authonomic nervous system tha calms the body, conserving its energy
Reflex
A simple, automatic response to sensory stimullus, such as the knee-jerk response
Endocrine
The body's slow chemical communcaition system, a set of glands that secret hormones into the bloodstream
Hormones
Chemical messengers that are manufactured by the endocrine glands, travle through the bloodstream, and affect other tissues
Adrenal glands
A pair of endocrine glands that sit just above the kidneys and secret hormones that help arouse the body in times of stress
Pituitary gland
The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates the growth and controls other endocrine glands
Lesion
Tissue destruction. A brain lesion is a naturlal or experimentall caused destruction of brain tissue
Electroencephalogram (EEG)
An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.
PET (position emission tomography) scan
A visual display of brain activity that detects wehre a radioactive form glucose goes while the brain performs a given task
MRI (magnetic resonance imaging)
A technique that uses magnetic fields and radio waves to produce computer generated images of soft tissue. MRI scans show brain anatomy.
fMRI (functional MRI)
A technique for revealing blooflow and, therefore, brain activity by comparing uccessive MRI scans. fMRI scans show brain function
Brainstem
THe oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brain stem is responsible for authomatic survival functions
Medulla
The base of the brainstem; controls hearbeat and breathing
Reticular formation
A nerve network in the brainstem that plays an important role in controlling arousal
Thalamus
The brain's sensory switchoard, located on top of the brainstem; it directs messages to the sensory recieving areas in the cortex and transmits replies to the cerebellum and medulla
Cerebellum
The "little brain" at the rear of the brainstem; functions include processing sensory imput and coordinating movement output and balance
Limbic system
Neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives
Amygdala
Two lima bean sized neural clusters in the limbic system; linked to emotion
Hypothalamus
A neural structure lying below the thalamus; it directs several maintance activies (eating, drinking, body temperature) helps govern the endocrine system bia the pitutiaaary gland and is linked to emotion and reward.
Cerebral cortex
The intricate fabirc of interconnected neural cells covering the cerebral hemispheres; the body's ultimate control and information-processing center
Glial cells (glia)
Cells in teh nervous system taht support, nourish, and protect neurons
Frontal lobes
Portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements
Parietal lobes
Portion of teh cerebral cortex lying at teh top of the head and toward the rear; recieves sensory imput for touch and body position
Occipital lobes
Portion of the cerebral cortex lying at the back of the head; includes areas that recieve information from the visual fields
Temporal lobes
Portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear
Motor Cortex
An area at teh rear of the frontal lobes that controls voluntary movements
Sensory Cortex
Area at the front of the parietal lobes that registers and processes body touch anbd movement sensation
Association areas
Areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking
Plasticity
The brain's abililty to change. especially durring the childhood by reorganizing after damange by building new pathways based on experience
Corpus callosum
The large band of neural fibers connecting the two brain hemispheres and carrying messages between them
Split Brain
A condition resulting from surgery that isolates the brain's two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them