Title

LeChatelier Principle and Spectrophotometry

 

Abstract

This experiment was designed to prove the Le Chatetlier principle. By placing differing dilution factors of hydrochloric acid into six tubes, we then took the tube that was the most in-between and performed a series of tests to see whether we could prove that a reaction can be reversed. We found that it could. We then took the most extreme two of these liquid dilutions and placed them in a spectrophotometer. This tested to see what wavelengths were being left behind as the light pasted thought the liquid.

 

Intro

In 1888, Le Chatetlier gave a succinct statement of the principle he had announced 4 years prior. It is: Every change of one of the factors of an equilibrium occasions a rearrangement of the system in such a direction that the factor in question experiences a change in a sense opposite to the original change. This experiment proved his theory. It also proved that light, when passed through a given substance, absorbs some of the wave lengths, providing colored light.

Experimental section

We first placed 5 ml of cobalt nitrate into six labeled test tubes. From there we added hydrochloric acid and water to each tube as is in the chart on the next page. Stirring well, we recorded the colors. After we had recorded all the colors we took the tube which had the most in-between color and divided the contents into three equal parts. The first part we cooled. The second part we warmed in hot water, and the third one we kept the same. After these had sat for a while, we took them out and again looked at the color of them. Next, the tube that had been in cold water was put in hot water, and the tube that was in hot water was put in cold water. For the umpteenth time we looked at the color. After all that was done, we got in line to use the spectrophotometer and while we were waiting, went over our results thus far. We also transferred test tubes 1 through 6 (look at the chart) into two cuvettes so that when we go there, we could use the light device right away. Finally we got there and put the samples into the spectrophotometer after having set the device to the correct zero by using clear water. After having gotten charts of the visible spectrum of light which passed though the substance, we printed them out and handed them to the all powerful chemistry professor to have copies magically made of them.

 

Results & discussion

As a result of the experiment we found that the test tube that had no HCl in it was pink and the test tube that had the greatest amount of HCl in it was violet and that the test tubes which less HCl were colors in-between the to extremes. The test tube which was the most in-between when cooled (turned fuchsia) or heated (turned violet) could be then reversed to show the opposite color, proving that almost every action has an equal and opposite reaction. There was a slight error however, for when we switched the tubes, they did not go quite back to the exact same color as they should have been. The most probable reason for that is because the first time they were heated and cooled, they were at room temperature, and the second time they were at much higher and lower temperatures, so they had a longer time in which to switch, but we kept them in for about the same length of time as before. When we tested the spectrophotometry, we found that the violet sample had much more of an absorbance value. This makes some sense, seeing as how the violet was much darker than the pink. These results could almost be predicted because, just looking at the color, if pink can be seen coming through this means that blue is being blocked (absorbed), and if blue can be seen coming through, this means that that red is being blocked.

 

Conclusions (main points)

Like the ying and the yang, so science has its reactions to its results. Whether you wether is a fair weathered weather, or whether he weathers the storm, hither and thither or wander, together youll never go wron-g. Whether it is a neutered male goat or cobalt nitrate, both can produce differing results, given the parameters put in place by you or someone/something else. The one constant is that the beginning of the tale and the tail end of the story both, almost always, have to be equal, have to leave nothing out. Also, the perception of color can be adapted, based on the color being left out as a result of the light passing through a given substance.

 

Reverences (full)

Park, John L. Intro. to Henri Le Chatelier's Principle. 1999, 2003. Park, John L. 11/3/04 <http://dbhs.wvusd.k12.ca.us/webdocs/Equilibrium /LeChatelier-Intro.html>

 

John Mionczynski. The Pack Goat. Pruett Publishing Company, September 1, 1992.

A

Abducent nerve (CN VI): The sixth cranial nerve. Innervates the lateral rectus muscle, which abducts the eye, or rotates it outward. See the Cranial Nerve Table.

Ablation: The removal or destruction of tissue.

Acetylcholine: A neurotransmitter that is important for memory and muscle movement.

Acoustic neuroma: A tumor which results from the growth of Schwann cells surrounding the acoustic nerve, CN VIII.

Activation Synthesis Hypothesis: a theory suggesting that dreams are a result of random activation of the cortex.

Acupuncture: A technique used principally for pain management and anaesthesia. An acupuncture practioner uses fine needles to manipulate the body's endogenous pain repression mechanisms.

Adenosine: A nucleotide consisting of adenine linked to the sugar ribose.

Adrenaline: Also called epinepherine, a neurotransmitter that is important for regulating heart rate.

Adrenocorticotrophin (ACTH): A peptide hormone released by the pituitary that stimulates the production of steroid hormones in the adrenal gland.

Affix: A prefix or suffix.

Agoraphobia: An extreme fear of open spaces. An anxiety disorder characterized by extreme fear of leaving home due to increased likelihood of having a panic attack outdoors.

Agnosia: Literally "not knowing," agnosia is the condition of not recognizing sensory stimuli. For example, someone with visual agnosia would have no trouble seeing an object, but lacks the ability to understand the image.

Allocentric: A spatial system referencing objects external to the body, as opposed to an egocentric system.

Alpha Motor Neuron: Large neurons in the ventral horn of the spine which innervate the force-producing skeletal muscle fibers.

Alphabetic principle: The principle that each letter represents a unit of sound (a phoneme).

Alzheimer's disease: A degenerative, age-related form of dementia.

Amacrine cell: A type of neuron in the retina which helps to shape the receptive fields of retinal bipolar cells through inhibitory influence.

Amblyopia: A condition resulting from strabismus in one eye. Vision in the deviated eye is lost due to weakened connections with visual cortex, resulting in a loss of focus in an otherwise healthy eye.

Amnesia: A cognitive disorder involving memory loss, typically as a result of a traumatic injury or a degenerative brain condition.

Amygdala: A part of the basal ganglia named for its almond shape. The amygdala is thought to be involved with emotion and memory formation.

Analgesic: The property of diminishing pain

Anencephaly: A terminal, developmental disorder that occurs when the neural tube fails to close at the front end, resulting in malformation of the brain.

Aneurysm: The swelling or rupture of an artery, resulting from increased arterial pressure due to a clot or obstruction.

Angular Gyrus: A section of the left temporal lobe involved in language processing, integrating information about letter shape, word recognition, meaning, and sound. It connects the occipital cortex with Wernicke's Area.

Anoxia: A lack of adequate oxygen, typically resulting in tissue injury and cell death; oxygen starvation.

Anterior cingulate gyrus: An area of the brain associated with motor control, pain perception, cognitive function and emotional arousal. A component of the limbic system.

Anthropometry: The comparative study of human body measurements.

Antonyms: Words that mean the opposite of each other.

Aphasia: Partial or total loss of the ability to express ideas or comprehend spoken or written language, resulting from damage to the brain caused by injury or disease.

Aqueous humor: Literally "water-like fluid," the aqueous humor fills the space between the cornea and the iris in the eye.

Asperger's Syndrome: A diagnosis given to high-functioning individuals with autism who have normal or above-average IQs and no clinically significant delays in language acquisition, age-appropriate self-help skills, or cognitive development.

Aspiration: Audible breath that accompanies some sounds when speaking.

Astigmatism: Aberrations in the surface of the cornea occurring during development. The resulting uneven corneal surface causes difficulties in focusing.

Astrocytes: Star-shaped glia cells that help form the blood-brain barrier and provide a support system for central nervous system axons.

Ataxic palsy: A type of motor control disorder characterized by uncontrolled muscle movement and loss of balance.

Athetoid palsy: A type of motor control disorder characterized by repeated involuntary slow, writhing movements.

Attention Deficit Disorder (ADD): A syndrome characterized by short attention span and poor impulse control.

Attention Deficit Hyperactivity Disorder (ADHD): A syndrome generally characterized by inattention, distractibility, impulsivity, and hyperactivity.

Attachment theory: Theory, first articulated by John Bowlby, that humans attach themselves to their primary caregiver, in a way similar tothough much more complicated thanimprinting in goslings and other animals. Attachment theory was arguably the first scientific approach to understanding things like separation anxiety, and has influenced much of the discussion in the area of child development in the latter twentieth century.

Atrophy: A wasting away of part of the body.

Atypical depression: a type of depressive illness whose symptoms may include oversleeping, overeating, mood brightening in response to positive events, and extreme sensitivity to rejection or adversity.

Auditory feedback: The process by which humans learn to speak utilizing hearing and vocalization. In auditory feedback sounds heard are repeatedly mimicked and fine-tuned until they can be perfectly reproduced.

Auditory Nerve: The eighth cranial nerve, also called the acoustic nerve, or the vestibulocochlear nerve. Bundled nerve fibers extending from the cochlea of the ear to the brain. The bundle contains two branches: the cochlear nerve, which transmits sound information, and the vestibular nerve, which delivers information about balance. See the Cranial Nerve Table.

Autism: The three core features of this pervasive developmental disorder which appears early in life are: qualitative impairments in social interactions; repetitive, restricted and stereotyped behavior patterns; and impairments in communication.

Autistic Savant: The name given to an individual with autism who also possesses extraordinary skills not generally exhibited by others.

Autistic spectrum: Term used to describe a range of symptoms generally associated with autism.

Autobiographical Self: a term used by Antonio Damasio to represent our notion of self in terms of traits we consider part of our identity. It depends on systematic memories of facts and experiences that we consider the essence of who we are.

Automatic word recognition: The ability to instantly recognize a word and access its concept.

Autonomic Nervous System: Also called the visceral nervous system. Located outside the brain and spinal cord. Obtains sensory information from internal organs and provides output to them.

Autoreceptor: A receptor that resides near the presynaptic terminals; when activated, it usually prevents further transmitter release.

Axon: An extension of a neural cell that transports information to and from the cell body, usually by an electrical impulse.

B

Balanced bilingualism: Equal fluency in both languages across contexts.

Basal Forebrain: the bottom surface of the forebrain, a region of the brain associated with emotional decision-making.

Basal Ganglia: A series of subcortical structures in the center of the brain that are principally responsible for motor tasks.

Basilar Membrane: A membrane inside the cochlea on which the hair cells rest. It is between the scala tympani and the scala media.

Behaviorism: School of psychological thought limited to the study of observable and quantifiable aspects of behavior.

Benign Paroxysmal Positional Vertigo: Disorder which causes dizziness, nausea, and imbalance. Results from the movement of calcium carbonate crystals in the ear.

Benzodiazepines: Drugs such as valium and librium, most frequently prescribed for anxiety.

Binaural: Relating to both ears.

Alfred Binet: (1857-1911) French psychologist credited with creating the first psychometric intelligence scale (1905).

Binet-Simon Scale: Testing device created by Alfred Binet and Theodore Simon in France in 1905; the precursor to the modern intelligence test.

Binocularity of vision: Vision with two eyes (or sensors) allowing the apprehension of stereoscopic depth.

Bipolar cell: A type of neuron in the retina which exhibits either on-center or off-center response properties. Bipolar cells are thought to be responsible for contrast and edge detection.

Bipolar disorder: manic-depressive illness, symptoms of which include alternating periods of depressive moodiness and high-energy activity.

Blastula: An early stage in animal embryology; in many species, a hollow sphere of cells surrounding a central cavity.

Blind spot: A spot in the visual field of each eye where the eye cannot see. The blind spot corresponds to the point in the retina where the optic nerve exits the eye, and which is devoid of photoreceptors.

Joseph Bogden: U.S. surgeon involved in the development of successful commissurotomy for the treatment of epilepsy in the early 1960s.

Bone conduction: Conduction of sound through bones directly to the cochlea, which is housed in the mastoid, a part of the temporal bone.

Bound morphemes: suffixes and prefixes; bound morphemes cannot stand alone.

Brain Hemisphere Laterality: The differences in the abilities of the right and left hemispheres of the brain.

Brainstem: The major route by which the forebrain communicates with the spinal cord and peripheral nerves. The brainstem controls, among other things, respiration and regulation of heart rhythms.

Broca's Area: The central region for the production of speech. Located in the frontal lobe, typically in the left hemisphere, Broca's area is responsible for the production of words, word sound, syntactic comprehension, and working memory.

Paul Broca: (1824-1880) French surgeon and anthropologist who first located a center of motor and speech in the brain, a region now known as Brocas Area.

Brodmann Area 17: An area of cortex in the occipital lobe. Also called the V1, or primary visual cortex, because it receives the earliest information from the eyes by way of the thalamus. Also called striate cortex because in cross section, it has a distinct band of white myelin within the cell layer.

C

Capillaries: the smallest of blood vessels, often just big enough to allow red blood cells to move in single file. Capillary beds are the site of nutrient and waste exchange for most tissues.

Capsaicin: The substance found in the white "ribs" of chili peppers which provide the peppers with their characteristic hot flavor.

Carbohydrate: The nutritional group consisting of simple and complex sugarspasta, sweets, and many fruits and vegetables fall into this category.

Causal inference: A hypothesis about the cause of an event.

CAT (Computerized Axial Tomography) Scan: A computer-mediated x-ray image depicting a cross-section of the body.

Cataract: A clouding of the eyes lens, typically a result of the aging process. Cataract causes dim or unfocused vision.

Causative comprehension: Understanding cause and effect.

Central executive: A component of the working memory models associated with coordinating cognitive functions.

Central Gray: Region of the midbrain that controls freezing during times of fear.

Cerebral Aqueduct: A channel for cerebrospinal fluid running near the brainstem. The cerebral aqueduct connects the third and fourth ventricles, which are fluid reservoirs within the brain.

Cerebral palsy: A developmental disorder characterized by motor control difficulties; cerebral palsy results from perinatal damage to brain tissue.

Central Nervous System (CNS): The "Central Station" to which the peripheral and visceral (autonomic) systems send their sensory information. The CNS takes that sensory information and responds to the peripheral and visceral systems with motor instructions. The two main structures of the CNS are the brain and the spinal cord.

Central Sulcus: A deep groove within the convolutions of the cerebral cortex that runs from the midline down the side of the brain and delineates the frontal lobe from the rest of the cortex.

Cephalometry: The science of measuring the heads of living humans.

Cerebellum: A large structure located high inside the hindbrain. Connected to the pons, medulla, spinal cord and thalamus. Helps control movement and some aspects of motor learning.

Cerebral Cortex: The outer, highly convoluted layer of the cerebral hemispheres. Responsible for perception, emotion, thought and planning.

Cerebral Hemispheres: The halves of the brain, each with its own specific functions. The left hemisphere is typically associated with speech, writing, language and calculation, and the right hemisphere is typically associated with spatial perception, visual recognition, and aspects of music perception and production.

Cerebrospinal fluid: a fluid that surrounds the brain and spinal cord, providing nutrients to nerve tissue, removing cellular waste products, and cushioning the brain.

Cervical Level (of the spine): Portion of the spine that lies closest to the brainstem, there are 7 cervical vertebrae.

Childhood Disintegrative Disorder: A pervasive developmental disorder related to autism characterized by regression to severe disability following development that is initially normal.

Cholesteatoma: Benign tumor in the middle ear resulting from the overgrowth of tissue during repair of a tear in the ear drum.

Cholinergic: Uses the neurotransmitter acetylcholine.

Noam Chomsky (1928-): American linguist whose book Syntactic Structures (1957) revolutionized the discipline of linguistics. Also an outspoken political critic, particularly of American foreign policy.

Chopper response pattern: An activity pattern exhibited by neurons in the cochlear nucleus called "chopper units." The chopper response pattern is characterized by repeated, rhythmic bursts of action potentials separated by relatively fixed time intervals.

Chromosome: thread-like structure of the cell nucleus that contains genetic information; they occur in characteristic matched pairs for each species, humans have 23 pairs.

Chronic: Of long duration.

Cingulate Gyrus: A cortical structure, part of the limbic system, that is directly over the corpus callosum along the medial side of each hemisphere. It is involved with emotion and attention.

Circadian rhythm: From the Latin "circa" meaning "about" and "diem" meaning "day", the term refers to any event that occurs cyclically every 24 hours.

Classical Conditioning: A type of learning in which an organism comes to associate different events; also called Pavlovian conditioning or associative conditioning.

Cleft transformation: A structure where a single clause is divided into two clauses, each with its own verb (It was the juice that the girl drank). Cleft transformation is challenging to understand because the object is moved to the beginning of sentence.

Cochlea: The inner ear. The location where the mechanical energy of sound is transduced into electrical signals that can be carried by the nervous system. The cochlea also contains the semicircular canals that are responsible for our sense of balance.

Cochlear Implant: A prosthetic, implanted, device that replaces the function of the cochlea in order to restore hearing. A microphone outside the head captures the sound and then transforms it into electrical signals which are sent to the auditory nerve directly.

Cochlear Nerve: The part of the VIIIth Cranial Nerve (auditory-vestibular or vestibulocochlear nerve) that carries information about hearing from the cochlea to the brainstem.

Cochlear Nucleus: One of the auditory nuclei in the brainstem.

Cognition: The mental processes by which knowledge or awareness is applied tor comprehension and problem-solving.

Cognitive interference: The theory that certain cognitive processes in the brain may conflict with other cognitive processes. See "Stroop Effect."

Cognitive map theory: One theory concerning how the brain represents physical spaces.

Commissurotomy: Surgery, generally for sufferers of severe epilepsy, in which the hemispheres of the brain are disconnected from one another by the severing of the corpus callosum, and occasionally the many other commissuries, or connectors.

Concept-driven logic: The student using concept-driven logic relies on the sentence's context and on common sense, rather than comprehending the words and the syntax, and sometimes does not understand the sentence correctly.

Conceptual system: Located all across the cortex, the conceptual system brings cognitive skills to bear on a word or concept for the purpose of comprehension.

Concussion: Changes of cerebral function caused by a direct or indirect force transmitted to the head. Symptoms include headaches, dizziness, confusion, vision impairment, nausea/vomiting or loss of consciousness.

Conditioned Stimulus (CS): In classical conditioning, an originally neutral stimulus that, after association with an unconditioned stimulus, comes to trigger a conditioned response.

Conditioned Response (CR): In classical conditioning, the learned response to a conditioned stimulus.

Conductive Hearing Loss: Hearing loss which disrupts the conduction of sound to the auditory nerve-involves pathology of the outer or middle ear.

Conjoined-clause analysis: The strategy that assumes two clauses of a sentence are joined by a conjunction.

Cone cell: A type of photoreceptor in the retina. Cone cells are responsible for high-acuity color and black and white vision.

Consolidation: A stage of memory formation during which long-term memories are created.

Content words: The nouns, verbs, adjectives, and adverbs.

Context Conditioning: A type of learning in which an organism associates its surroundings with a particular stimulus.

Contralateral: Related to the opposite side, as when functions on the right side of the body are controlled by the left side of the brain.

Cornea: A thin, clear layer of tissue which protects the front of the eye. The cornea provides the eye with most of its optical focusing power.

Corneal blink reflex: A normal reflex blinking induced by touching the cornea lightly.

Corpus Callosum: A large bundle of nerve fibers that connects the left and right cerebral hemispheres.

Cortex: The surface of the brain.

Corticospinal Tract: Direct pathway from the cortex to the spine, involved in voluntary motor control.

Cortisol: A steroid hormone produced by the adrenal cortex.

Craniometry: The science of measuring skull volume.

Cortical Plasticity: The ability for connections between neurons to be modified within the cortex.

Critical period, or sensitive period: The period of development during which an individual can permanently acquire certain behaviors or attributes; during this period, the individual is sensitive to the experiences or environmental influences that foster these capacities.

Cranial nerves: A series of twelve large nerve bundles that control a variety of functions in the head and neck. See the Cranial Nerve Table.

Cytokines: Non-antibody proteins released by certain cells (maternal and fetal during pregnancy) that may have stimulating, repressive, or even toxic effects on other cells and tissues.

D

DNA: see Deoxyribonucleic Acid

Declarative memory: Memory for semantic information that can be consciously (and verbally) recalled.

Decode: To use the alphabetic principle (that each letter represents a sound) to sound out the phonemes of a word and then blend those phonemes into a recognizable word.

Decussation: A crossing over of nerve fiber tracts from one side of the body's midline to the other. Decussations typically result in the right hemisphere of the brain controlling the left side of the body, and the left hemisphere controlling the right side of the body.

Demyelination Disease: A disease of the nervous system in which myelin is damaged. Must be differentiated from dysmyelination disease. In the former, normal myelin is damaged; in the latter, the myelin is probably abnormal in the first place.

Dendrite: A branching extension from the neuron cell body that receives information from other neurons.

Dendritic Branching: The process in which the neuron is stimulated to produce new dendrites, which increase the neuron's communicative ability.

Dendritic sprouting: A process in which the branches of a neuron that receive information (dendrites) multiply to increase the communicative power of the neuron.

Deoxyribonucleic Acid (DNA): A long, thread-like molecule contained in the nucleus of cells that encodes the genetic information of an organism. DNA is a remarkable molecule because it can self-replicate. Half of a child's DNA contains genetic information from the mother, and half from the father.

Derivational morphemes: An affix added to a word that changes the root word's meaning and often its part of speech.

Derived word: A word formed by adding a derivational morpheme to a root word.

Rene Descartes: (1596-1650) French philosopher who founded analytic geometry; often remembered for his ideas about a split between mind and body.

Derivational morphemes: Suffixes and prefixes that change the word's meaning and can change the word's part of speech.

Derived word: A word formed by adding a derivational morpheme to a root word.

Diathesis-Stress Model: A model for all types of illness that suggests one can have a certain predisposition for a particular disorder that may or may not manifest itself, depending on the environmental conditions.

Diencephalon: That part of the forebrain which gives rise to the thalamus, hypothalamus, infundibulum (pituitary stalk), and part of the pituitary gland.

Digraphs: A combination of two letters that represent one sound when spoken, such as the ch in child.

Diphthongs: The vowel sound produced when the tongue glides from one vowel sound toward another, such as the oy in boy.

Direct retrieval route: The route a word takes through the brain when its meaning is automatically accessed.

Discrimination: In classical conditioning, the organism will only respond to cues that are very similar to the conditioned stimulus.

Diurnal: An organism that is generally awake during daytime and asleep during night.

Dopamine: A neuromodulator acting principally through structures of the basal ganglia. Dopamine is associated with reward pathways, and low levels of dopamine are characteristic of Parkinson's disease.

Dorsal: In humans, closer to the back of the body.

Dorsolateral prefrontal cortex: An area on the lateral aspect of the brain near the front that is associated with executive function, decision making, and working memory.

Drosophila: Genus name of the common fruit fly; extremely useful in the study of genetics.

Dyscalculia: A "number blindness" that is an impairment of the ability to recognize or manipulate numbers.

Dyskinesia: A condition characterized by abnormal involuntary movements.

Dyslexia: A reading impairment affecting the ability to identify, sound out, or understand written letters and words that is not attributable to sensory deficit or cognitive impairment.

Dystonia: Sustained muscle contractions causing abnormal motor control. For example, co-contraction of flexors and extensors (opposing muscle groups) resulting in the lack of motor control of a limb.

E

Eardrum: Also referred to as the tympanic membrane. The membrane separating the external ear canal from the middle ear.

Ectoderm: The outermost of the three embryonic tissue layers first delineated during gastrulation; gives rise to the skin, sense organs and nervous system.

Ectopic cells: Cells that have migrated incorrectly and cannot develop into functioning cells as a result P a minor brain malformation.

Edema: Swelling caused by the accumulation of an excessive amount of fluid in cells, tissues or cavities.

Thomas Edison: (1847-1931) US inventor responsible for the creation of the incandescent electric light (1879) and the phonograph (1877).

Ego: According to Sigmund Freud, the rational part of human consciousness.

Egocentric: A spatial system referencing the self, as opposed to an allocentric system.

Albert Einstein: (1879-1955) German-born (Swiss/U.S. citizen) physicist. Discovered Special Theory of Relativity (1905); won Nobel Prize in Physics in 1921.

Electroencephalogram (EEG): A record of the summed activity of cortical cells picked up by wires placed on the skull.

Embedded clause: A clause that refers to the subject or object of another clause within the sentence.

Embolism: Obstruction of a vessel by a transported clot or mass, called an embolus.

Embryo: A young organism while it is still contained within a protective structure such as a seed, egg or uterus.

Encephalopathy: a disease or injury of the brain

Endocrine system: System of glands that release hormones into the circulatory system; regulated by the hypothalamus.

Endoderm: The innermost of the three embryonic tissue later first delineated during gastrulation; gives rise to the digestive and respiratory systems.

Endolymph: Fluid in the scala media.

Endorphins: molecules in the body that are part of the pain signalling pathway; endorphins supress pain sensation.

Enlightenment: Eighteenth century philosophy of reason and individualism.

Entorhinal cortex: evolutionary older cortex in the temporal lobes, located near the hippocampus; may be involved in learning and memory.

Enzyme: Protein molecule that catalyzes reactions between other substances.

Epidermis: In plants and animals, the outermost cell layers.

Epilepsy: A neurological disorder caused by uncontrolled electrical activity that spreads throughout the brain, causing seizures that can last from seconds to several minutes.

Equilibrium: Sense of balance.

Etymology: The study of word origin.

Eugenics: The science of improving hereditary qualities (of a race or breed) through mating control.

Eustachian Tube: Thin tube which connects the middle ear to the back of the throat and acts to drain the ear and to equalize the air pressure across the ear drum.

Executive processes: Cognitive tasks related to decision-making, associated with the frontal lobe of the brain.

External auditory meatus: The ear canal.

Extrastriate: Visual areas in the cerebral cortex which are "downstream" of primary visual cortex. Extrastriate areas are associated with higher order features of vision, such as face recognition and spatial awareness.

F

Facial nerve (CN VII): The seventh cranial nerve, responsible for facial movements, taste, salivation, and lacrimation. See the Cranial Nerve Table.

Finger agnosia: Confusion in identifying individual fingers, literally "not knowing" one's own fingers.

fMRI: functional magnetic resonance imaging, which uses a scanning machine to measures changes in the brain's metabolic activity.

Focal dystonia: A localized dystonia such as one affecting just the hand.

Factor Analysis: Analytical process of converting two or more measurements into linear combinations of usually independent variables.

Forebrain: (See Prosencephalon)

Fovea: A region near the center of the retina which has the highest concentration of photoreceptors. The fovea is the part of the retina used to read or to analyze detailed stimuli.

Free morphemes: Root words; free morphemes can stand alone.

Free radicals: unusually charged ions that are highly chemically reactive. The free radical form of oxygen (O-) is responsible for a type of damage to neurons called "oxidative injury."

Frontal cortex: An area of the brain associated with higher cognitive functions including planning and motor control.

Frontal lobe: One of the four divisions of each hemisphere of the cerebral cortex that include the parietal, temporal, occipital. The site of emotions, personality, cognitive and motor functions.

Fusiform gyrus : Holds the functional regions responsible for color, identification of a face and recognition of facial expression . Damage to any of these areas leads to a deficit specific for that mode of visual function.

Functional Magnetic Resonance Imaging (fMRI): A technique for imaging brain activity using magnets. fMRI is able to detect brain activity by taking advantage of the fact that deoxyhemoglobin has a different magnetic profile than oxyhemoglobin. Deoxyhemoglobin is concentrated in areas of high cellular metabolism, which correlates to high cellular activity.

G

Ganglion cell: A type of neuron in the retina. These are the only retinal neurons which communicate directly with the rest of the brain.

Joseph Gall: (1758-1828): German physician who founded phrenology.

Gamma Motor Neuron: Motor neurons in the spine which innervate muscle spindles.

Howard Gardner: (1943-) Harvard psychologist whose 1983 book Frames of Mind: The Theory of Multiple Intelligences revolutionized thinking about intelligence testing.

Gene: The smallest hereditary unit. A gene is a section of DNA that encodes a protein, and proteins in turn control many characteristics of an organism.

General Intelligence Factor: Psychometric measurement that suggests a global capacity for intelligence.

Generalization: In classical conditioning, the organism will repond to cues that approximate the conditioned stimulus, e.g., a tone that is very close in pitch to the CS.

Generalized Anxiety Disorder (GAD): A psychological disorder characterized by long lasting, intense worry and a pervasive sense of dread.

Genome: The complete set of genes within an organism.

Genomics: The study of the structure and function of the genome within an organism.

Gist: The main point.

Glial Cells: A range of cell types that act to support the neural network by providing structure and nourishment. In some cases, glia may be involved in modulating neural signals.

Globus pallidus: A nucleus of the basal ganglia that is involved in the coordination of voluntary movement.

Glottalization: the closing of the gap between the vocal folds when speaking.

Glial cells: Cells found only in the nervous system that do not conduct action potentials; they provide a support system for the neurons.

Glossopharyngeal nerve (CN IX): The ninth cranial nerve, responsible for taste and swallowing. See the Cranial Nerve Table.

H.H. Goddard: The first scientist to translate the Binet-Simon scale into English; father of the American eugenics movement

Golgi Tendon Organ: Stretch receptor located in the tendon connecting muscle to bone, provides information on contractile force.

Stephen Jay Gould: (1941-) Harvard paleontologist, geologist and biologist best known for his popular science writing in Natural History.

Grand mal seizure: In epilepsy, a type of seizure characterized by loss of consciousness, muscle spasms and rigidity.

Graphesthesia: Ability to recognize letters traced on the hand.

Growth cone: Located at the tip of a sprouting axon, uses chemical messages to determine the axon's correct path.

Gyrus (Plural, Gyri): Any rounded external partbulgeof the convolutions on the cortex of the brain (as opposed to a valley).

H

Helicotrema: The channel at the tip of the cochlea where the scala vestibuli and the scala tympani are continuous.

Hemisphere: Half of the brain, the right or left.

Richard J. Hernstein: Co-author of 1994s controversial book, The Bell Curve, which is about intelligence and race in the United States

Herschel, Sir John: (1792-1