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Absence seizure: seizure in which patients have a transient loss or impairment of consciousness.

Absolute refractory period: a brief period after the initiation of an action potential during which it is impossible to elicit another action potential in the same neuron.

Action potentials: the electrical signal of the axon.

Addiction: chronic, relapsing brain disease that is characterized by compulsive drug seeking and use, despite harmful consequences.

Addiction is a disease: an idea that states drug addiction is no different from other chronic diseases like diabetes and cardiovascular disease, and thus needs to be treated as a distinct medical disorder.

Adenosine: neurotransmitter that accumulates in the brain during wakefulness, implicated as an important ‘sleepiness factor’.

Adjuvant: a chemical added to a vaccine that consists of a purified antigen. The adjuvant mimics a PAMP and stimulates the innate immune response.

Affinity: preference.

Agonist: drug that facilitates the effects of a neurotransmitter on the postsynaptic cell.

Alkaline: opposite of acidic; describes a substance with a pH greater than 7, demonstrating that it is basic in nature.

Alpha bond: a chemical bond linking monosaccharides to form disaccharides or a complex carbohydrate that is easily digested.

Alzheimer’s disease (AD): major cause of dementia in old age, characterized by neurofibrillary tangles, amyloid plagues and neuron loss.

Amino Acid: a monomer used to build proteins. Contains a nitrogen-containing amino end, and an acid end.

Amino Group: a chemical group that contains nitrogen and hydrogen. This group is basic, or alkaline.

Amnesia: a condition in which one’s memory is lost. Patients with amnesia often lose pre-existing memories; this is called retrograde (backward) amnesia. Sometimes patients with amnesia also lose the ability to form new long-term memories; this is called anterograde (forward) amnesia.

Amplitude: refers to how large (height) a wave is from peak to peak.

Amylase: an enzyme that digests starch and glycogen.

Amylopectin: type of starch consisting of branched sugar chains.

Amylose: a type of starch consisting of long unbranched sugar chains.

Analgesics: drugs that reduce pain.

Anemia: a condition marked by deficiency of red blood cells or hemoglobin in the blood, resulting in fatigue, pale skin and weakness.

Anterograde transport: movement of materials from cell body to axon terminals.

Antibiotic: a medicine or chemical that destroys or inhibits the growth of microorganisms.

Antibodies: proteins produced by the immune system to identify and eliminate foreign bodies.

Antigen: a part of a molecule that can be recognized by a receptor. It may be part of a protein, in which case it is a sequence of between five and fifteen amino acids, a sugar, or a lipid.

Antigen-specific: the idea that one receptor specifically recognizes one antigen.

Antioxidant: a substance that inhibits oxidation.

Antiretroviral drugs: drugs that stop a retrovirus replicating.

Aphasia: deficit in the ability to use or comprehend language caused by brain damaged.

Apoptosis type of cell death in which the cell uses specialized cellular machinery to kill itself.

Appetitive phase: the phase of motivated behavior where subject seeks out a goal.

Arousal neurons: neurons located in the brainstem that when active keep us awake and alert.

Asymptomatic: without symptoms.

Asymptomatic carrier: a person or other organism that has contracted an infectious disease, but has no symptoms.

Attentuate: to weaken.

Autonomatic nervous system: part of the PNS that controls the function of organs and glands.

Axon: projection of a neuron that functions to conduct electrical impulses away from a neuron’s cell body.

Axon hillock: specialized part of a neuron‘s cell body that connects to the axon. As a result, the initial segment or axon hillock is the site where action potentials originate.

Axon terminals / Presynaptic terminals: swellings at the end of the axon‘s branches that server as the transmitting site of the presynaptic cell.

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Basal Metabolic Rate: the rate that the body uses energy while at rest to keep vital functions going, such as breathing and keeping warm.

Beta bond: a chemical bond linking monosaccharides to form disaccharides or a complex carbohydrate that is not easily digested.

Bile: a fluid that is created in the liver, and stored in the gall bladder until needed. Bile aids in digestion by making hydrophobic lipids absorbable in water.

Biofilm: an aggregate of microorganisms that attach to the surface of a structure. Dental plaque is an example.

Botulism: a rare but serious paralytic illness caused by the botulism toxin, produced by Clostridium botulinum.

BPA: Bisphenol A; a synthetic compound found in plastics used to store food or beverages.

Bran: a portion of the wheat kernel that contains B vitamins and fiber. The bran is included in whole wheat fiber.

Breaking point: the point at which an animal will no longer expend the effort required to receive a reward.

Broca’s area: area of left frontal lobe that is critical for the production of speech.

Bubonic plague: is a severe systemic infection caused by the bacterium Yersinia pestis

Budding: a form of viral shedding by which enveloped viruses obtain their envelope from the host cell membrane by bulging.

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Calorie: a unit of heat energy. 1 Calorie = 1,000 calories = 1 kilocalorie.

Caloric Density: the number of Calories relative to a volume of food.

Calorimetry: the measurement of quantities of heat.

Carboxyl Group: chemical group that contains carbon, oxygen and hydrogen. This group is acidic.

Carcinogen: able to cause cancer.

Cardiovascular: describes something that involves the heart or the blood vessels (arteries and veins).

Cardiovascular Disease: also called heart disease. A disease of the heart or blood vessels.

Carbohydrates: a large group of compounds occurring in foods, including sugars, starches and fiber. Found in grains, produce, desserts and sweet beverages.

Causation: when a change in one thing results in a change in another.

Cell body: part of the neuron containing the nucleus, but not including the axon and dendrites. Also called the soma.

Cellulose: an insoluble complex carbohydrate that is the main constituent of plant cell walls. Consists of long chains of glucose monomers.

Central nervous system (CNS): controls the brain and spinal cord.

Cerebrospinal fluid: the fluid that bathes the brain and spinal cord.

Cervix: the lower, narrow portion of the uterus.

Charcot-Marie Tooth Disease (CMTD): disease in which myelin within the peripheral nervous system is damaged.

Chemical digestion: breaking up polymers of food into their respective monomers using chemicals and enzymes.

Chemotaxis: the movement of a bacterium based on the chemicals in its environment.

Cholesterol: a molecule that contains loops or rings of carbons. Used in cell membranes and to make hormones.

Chronically: lasting for a long period of time.

Chylomicron: a lipoprotein that carries dietary fat through the lymphatic system to the blood.

Chyme: the acidic mix of food and gastric juices that passes from the stomach to the small intestine.

Cilia: finger-like protrusions in the intestines that help propel substances, particularly mucus.

Ciliated: having cilia, or mobile finger-like organelles.

Circadian: recurring naturally on a twenty-four-hour cycle.

Cis: a shape of chemical bond where two types of structures lie on the same side of the bond. Will make the bond have the shape of a C, creating a bend in the molecule.

Codon: a set of three nucleic base pairs (DNA building blocks) that code for one amino acid.

Combustion: the process of burning something.

Commensal flora: the microbes that normally inhabit our bodies and co-exist with us without causing disease. See Commensalism.

Commensalism: a symbiotic relationship in which one organism derives benefit and the other is unharmed.

Complex: having a structure that is neither purely helical nor icosahedral, possibly with additional structures.

Complex partial seizures: partial seizures in which patient loses consciousness.

Conduction aphasia: language disorder in which patients can understand language, and speak without any problem, and speak without any problem, but they omit parts of words or substitute incorrect words. See aphasia.

Conduction of the action potential: movement of the action potential down the length of the axon.

Conjunctiva: a clear mucus membrane that covers the whites of the eyes and lines the eyelids.

Connective tissue: a tissue that connects, supports, binds or separates other tissues or organs.

Consummatory phase: the phase of motivated behavior where the subject actually consumes the goal, whether that goal be a drug, food, or sex.

Convulsive seizure: seizure involving uncontrollable jerking of the body.

Correlation: a connection between two things.

Cornea: the transparent front part of the eye that covers the iris and pupil.

Creutzfeldt-Jakob disease: a degenerative neurological disorder that is incurable and invariably fatal, sometimes called the human form of mad cow disease.

Crimea: a peninsula to the south of the Ukraine.

Cyanosis: blue or purple coloration of the skin due to tissues being low on oxygen.

Cytokines: small cell signaling proteins.

Cytoplasm: the inner material of the cell that is enclosed by the plasma membrane and surrounding the nuclear membrane (when present).

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Dendrites: branched projection(s) of a neuron that functions as the receptive area of a neuron.

Dendritic spines: tiny spikes of various shapes that are located on the surfaces of many dendrites and are the sites of synapses.

Dementia: a chronic mental disorder marked by poor memory, personality changes and impaired reasoning.

Demyelination: the loss of myelin insulating neurons.

Denaturation: a process in which the structure of a protein is altered due to exposure to heat or specific chemicals or enzymes.

Deoxyhemoglobin: hemoglobin once it has delivered oxygen to body tissues.

Dependence: the state of drug use in which the user requires drug to maintain normal bodily function.

Depolarize: to decrease the resting membrane potential. Decreasing membrane potential means that the membrane potential is becoming more positive.

Depressant: belong to the class of drugs that decrease the activity of the central nervous system.

Dermatitis: a condition of the skin in which it becomes red, swollen and sore. Results from direct irritation of the skin by an external agent or an allergic reaction.

Diabetic neuropathy: disorder in which nerves of the body are damaged due to high blood sugar levels resulting from diabetes.

Diffusion: the net movement of molecules from areas of high concentration to areas of low concentration.

Digestible Energy: the energy that is available by digestion. This can be measured as the difference between the amount of energy eaten and the amount of energy excreted in the feces.

Diplococcus: cocci that grow in pairs.

Disaccharide: any of the sugars that contain two monosaccharides linked together. Sucrose, lactose and maltose are common disaccharides.

Distributed processing: theory suggesting that information is processed in several different parts of the brain.

Drug abuse: overuse of a drug by an individual.

Drug addiction: the continued compulsive use of drugs despite adverse health or social consequences.

Dynein: minus-end directed motor that carries cargo from the axon terminals to the cell body along microtubules.

Dystentery: bloody diarrhea with severe abdominal pain.

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Effector cells: lymphocytes that have clonally expanded and are primed to respond to a threat.

Electroencephalogram (EEG): measure of gross electrical activity of the brain, commonly recorded through scalp electrodes.

Electrolytes: salts and minerals that can conduct electrical impulses in the body. Sodium and potassium are important electrolytes that must be consumed in the diet.

Electrostatic pressure: the repulsion of like charges and the attraction of opposite charges.

Emulsifier: a substance that stabilizes a blend of fats and water.

Endemic: prevalent in a given area; persistent.

Endocytosis: the process by which cells absorb small molecules by engulfing them. It differs from phagocytosis, which is used to internalize large particles like bacteria, in the size of particle ingested.

Endoplasmic reticulum: organelle in the cell that forms a network of tubules and vesicles. It functions to synthesize proteins and lipids as well as metabolize carbohydrates.

Endosome: a membrane bound vesicle that is produced when a cell engulfs material from the extracellular space.

Endosperm: a large portion of the wheat kernel that is used to produce white flour. The endosperm contains most of the protein and carbohydrates in wheat.

Enzymes: proteins that catalyze, or increase the rate of, chemical reactions.

Epidemic: an outbreak of disease greater than would otherwise be expected at a particular time and place.

Epithelia: cells lining the inside of the body cavity. They are often ciliated.

Essential amino acid: an amino acid that is required for life but cannot by synthesized in high enough quantities by the body so it must be consumed in the diet.

Essential fatty acids: fatty acids that humans cannot make on their own, so must be eaten in the diet.

Eukaryotes: organisms that contain a membrane bound nucleus.

Evade: to avoid capture or recognition.

Excitatory postsynaptic potentials (EPSP): graded postsynaptic depolarizations, which increase the likelihood that an action potential will be generated.

Exocytosis: process by which the contents of membrane bound vesicles are released to the exterior through fusion of the vesicle membrane with the cell membrane.

Extracellular: outside of the cell.

Extracellular matrix: a fine meshwork of proteins outside cells in a tissue that holds the cells in place.

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Fasting: a period of time when no food is consumed.

Fast-scan cyclic voltammetry: a technique used to measure neurotransmitter release in the brain of an awake, freely moving animal by inserting a microsensor that detects the presence of specific neurotransmitters at very fast rates.

Fat-soluble: describes a substance that dissolves in fats, not water.

Fatty acids: type of molecule that is naturally in fats and oils with a long chain of carbons. See lipids.

FDA: Food and Drug Administration; a federal agency responsible for monitoring trading and safety standards in the food and drug industries.

Feasting: a period of time when food is consumed, such as during a meal.

Feed-forward inhibition: control mechanism whereby the output of one pathway inhibits the activity of another pathway.

Fiber: an indigestible dietary substance consisting of a large number of sugar monomers joined together by beta bonds. Cellulose and pectin are examples.

Flora: the bacteria and other microbes within a host.

Food Additive: a chemical, or chemicals, added to food to improve its flavor, appearance or shelf life.

Food Contaminant: harmful chemicals or microorganisms that unintentionally occur in food from growing or processing.

Food Preservative: a substance added to a food product to prevent spoiling by preventing microbial growth, oxidation, or early ripening.

Food Shed: an area of land including where food is produced, transported to, and consumed.

Frequency: refers to how long (length) a wave is from trough to trough.

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Gamma rays: form of electromagnetic wave with shorter wavelength than X-rays.

Gastric lipase: an enzyme that breaks down triglycerides that is produced in the stomach. See lipase.

Gastroenteritis: inflammation and pain of the stomach and intestines.

Generalized seizures: seizures that involve the entire brain.

Genome: the genetic material a cell (or a virus) uses to replicate itself.

Germ: a small portion of the wheat kernel that is the sprouting section of the seed. The germ contains B vitamins and is included in whole wheat flour.

Glial cell: several classes of non-neuronal cells of the nervous system.

Glucose: a simple sugar that is an important energy source throughout the body, but especially in the brain.

Glycerol: a water-soluble component of triglycerides that connects the three fatty acids together.

Glycogen: a substance in the liver and some muscles that is a store of carbohydrates. Consists of highly branched sugar chains.

GMO: Genetically Modified Organism; an organism in which the genetic material has been altered in a way that does not occur in nature.

Gonhorrea: a sexually transmitted disease that often causes no symptoms in either men or women, but which can lead to infertility in women.

Grand mal seizure: (also known as tonic-clonic seizure) type of generalized seizure that affects the entire brain.

Granuloma: a tiny collection of immune cells that wall off a pathogen to prevent further infection.

GRAS: Generally Recognized As Safe; a substance that is generally recognized as safe under the conditions of its intended use.

Grey matter: portions of the nervous system that appear grey in color because they are composed of neuron cell bodies and unmyelinated axons.

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H1N1: a subtype of influenza A virus.

HDL: high-density lipoprotein. A type of lipid-carrying protein in the blood that protects against cardiovascular disease by removing cholesĀ­terol from arteries or tissues.

Heavy metal: a metal with relatively high density or a high relative atomic weight. Lead, mercury and cadmium are all heavy metals.

Helical: having the shape of a helix or spiral.

Helper T cells: an important immune cell that regulates immune responses.

Hemoglobin: protein responsible for transporting oxygen in the blood.

Hereditary spastic paraplegia (HSP): group of inherited disorders that are characterized by progressive weakness and stiffness of the legs, and can be caused by defects in axonal transport.

Homeostasis: tendency to relatively stable equilibrium.

Hormone: a chemical message that is produced by one tissue in the body and transported in the blood to another tissue.

Hydrophilic: ‘hydro’ means ‘water’, ‘philic’ means ‘loving’. Having a tendency to mix with or dissolve in water. See water-soluble.

Hydrophobic: ‘hydro’ means ‘water’, ‘phobic’ means ‘fearing’. Tending to repel or fail to mix with water. See fat-soluble.

Hyperpolarize: to increase the resting membrane potential. Increasing membrane potential means that the membrane potential is becoming more negative.

Hypertension: abnormally high blood pressure.

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Icosahedral: a regular polygon with 20 identical equilateral triangle faces.

Inhibitory postsynaptic potentials (IPSP): graded postsynaptic hyperpolarizations, which decrease the likelihood that an action potential will be generated.

Inoculate: to give a small amount of something that will grow, like an infectious agent.

Insoluble fiber: dietary fiber that is not water-soluble. This fiber adds bulk to the diet, preventing constipation.

Insomnia: disorder of going to sleep and staying asleep.

Intracellular: within cells.

Intracranial self-stimulation: a method that involves implanting electrodes into an animal’s brain and then allowing the animal to electrically stimulate the electrode to activate that brain region.

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Keratin: protein that provides the structure for skin, nails and hair.

Kinesin: plus-end directed motor that carries cargo from the cell body to the axon terminal along microtubules.

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Lactase: an enzyme that breaks down the disaccharide lactose into one glucose and one galactose monomer.

Latent: dormant or inactive.

LDL: low-density lipoprotein. A type of protein that transports lipids in the blood from the liver to tissues and arteries.

Legumes: a family of plants with seeds that grow in long cases. Beans, peas and peanuts are legumes.

Lingual lipase: an enzyme that breaks down triglycerides that is produced in the mouth. This enzyme is active in infants, but loses activity in adults.

Lipase: an enzyme that breaks down triglycerides to fatty acids and glycerol.

Lipids: a class of compounds called fatty acids, including oils and solid fats.

Lipoprotein: a group of water-soluble proteins that combine with and transport lipids in the blood.

Local potentials: small changes in voltage (membrane potential) due to dendritic signaling.

Lumen: the central cavity of a hollow structure in the body. During digestion, food passes through the lumen of each organ in the digestive tract.

Lymphatic system: a network of vessels through which fluid-containing white blood cells are transported throughout the body.

Lyse: death of a cell by breaking down the membrane.

Lysis: the breaking down or rupture of a cell.

Lysozyme: an enzyme found on the skin and in saliva that can lyze the cell walls of gram-positive bacteria.

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Macronutrients: a substance required in relatively large amounts by living organisms, namely carbohydrates, lipids and protein. See nutrient.

Maltase: an enzyme that breaks down the disaccharide maltose into two glucose monomers.

Mechanical digestion: breaking up food into smaller chunks by force, such as chewing.

Melatonin: so-called ‘hormone of darkness’ released by the pineal gland. When light levels fall melatonin levels rise.

Membrane Proteins: proteins attached to or associated with the membrane of a cell.

Meninges: protective membranes that cover the brain and spinal cord.

Merozoite: the form of plasmodium that infects red blood cells.

Metabolic Syndrome: a combination of medical disorders that, when occurring together, increases the risk of developing cardiovascular disease and diabetes.

Micelle: a vesicle used to transport lipids that has a hydrophilic exterior and a hydrophobic interior.

Microbe: a microorganism, such as a bacteria or virus, that causes a disease or fermentation.

Microbiome: the community of microorganisms that live in or on our bodies.

Microdialysis: a technique used to measure neurotransmitter release in the brain of an awake, freely moving animal by collecting samples of extracellular fluid and then analyzing the samples biochemically.

Micronutrients: a substance required in relatively small amounts by living organism, like vitamins and minerals. See nutrient.

Microvilli: even small than the villi, microvilli are projections that cover the villi.

Minerals: basic elements that are required for biological reactions.

Minus-end: end of microtubules oriented toward the cell body.

Minus-end directed motors: molecular motors that travel toward the minus-end of microtubules, and thus carry cargo from the axon terminal.

Monomer: ‘mono’ means ‘one’, ‘mer’ means ‘part’. A molecule that can be bonded to identical molecules to form a polymer.

Monosaccharide: any of the sugars that cannot be hydrolyzed to give a simpler sugar. Glucose, fructose and galactose are the monosaccharides.

Morbidity: illness, loss of function, and disability.

Morphology: the physical form or structure of a microbe.

Mortality: a measure of the number of deaths from a particular disease in a given population.

Mucous membranes: the lining of cavities that are exposed to the outside environment and internal organs.

Multiple sclerosis (MS): disease in which myelin within the central nervous system is damaged.

Myelin: fatty substance that insulates most nerves.

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Narcolepsy: a disorder characterized by daytime sleep attacks and loss of muscle tone.

Natural selection: the process of increasing the level of offspring with an advantageous trait. This is a fundamental part of evolution.

Negative feedback / Feedback inhibition: control mechanism mechanism whereby activity of a circuit ends up inhibiting the activity of the circuit.

Negative symptom: symptom in which one loses a normal behavior.

Neuron: cells of the nervous system that are specialized for the reception, conduction and transmission of electrochemical signals.

Neurotransmission: signaling between nerves.

Neurotransmitters: chemicals that are released by the axon terminals and convey the message across the synapse to another cell.

Nerve degeneration: a deterioration of the function or structure of the nerves.

Nodes of Ranvier: gaps between adjacent myelin segments on an axon.

Non-convulsive seizure: seizure without jerking.

Non-essential amino acids: amino acids that can by synthesized by humans. See essential amino acid.

Non-rapid eye movement (NREM) sleep: sleep stages 1 through 4, during which sleepers are still and EEG waves decrease in frequency and increase in amplitude.

Nucleoid: a region within prokaryotes that contains the nuclear material, such as the DNA. It is not enclosed by a membrane.

Nucleoside Triphosphate: the power currencies of a cell.

Nucleus: the DNA containing structures of cells.

Nucleus accumbens (NAc): brain structure that plays an important role in rewarding and reinforcing effects of many abused drugs.

Nutrient: a substance in food that provides nourishment for growth and maintenance of essential biological functions.

Nutritive Value: a measure of the contribution of a food to the overall nutrient content of a diet. Foods with a lot of vitamins and minerals will have a higher nutritive value.

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Obstructive sleep apnea: condition in which breathing stops while you are asleep because the airway has become narrowed, blocked, or floppy.

Omega-3 fatty acid: an unsaturated fatty acid that occurs mainly in fish oils. Contains three unsaturated bonds.

Omega-6 fatty acid: an unsaturated fatty acid that occurs mainly in vegetable oils. Contains two unsaturated bonds.

Opiates: the class of drugs with pain reducing qualities.

Orexin neurons: neurons located in the hypothalamus that use the neurotransmitter orexin. When active, these neurons activate the arousal neurons in our brainstem to keep us awake. Damage to these neurons has been implicated in narcolepsy.

Osmosis: movement of water molecules through a selectively permeable membrane that balances out an unequal concentration across that membrane.

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Pain: unpleasant sensory and emotional experience associated with actual or potential tissue damage.

Pain threshold: the intensity of a stimulus at which a subject says, ‘It’s painful’ half of the time, and, ‘It’s not painful’ the other half of the time.

Pain tolerance: maximum level of pain people will voluntarily accept.

Pancreatic amylase: an enzyme that digests starch and glycogen that is made in the pancreas, and secreted into the small intestine. See amylase.

Pancreatic lipase: an enzyme that breaks down triglycerides that is produced in the pancreas and secreted into the small intestine. See lipase.

Pandemic: an epidemic that is spreading through human populations across a large region.

Partial seizures: seizures that do not involve the entire brain.

Pasteurization: heating a food or beverage to a specific temperature for a set length of time to kill harmful microorganisms.

Pathogenic: disease causing. From ‘pathogen’, a bacterium, virus, or other microorganism that can cause disease.

PCR: a way to detect DNA.

Pectin: a soluble gelatinous complex carbohydrate that is present in ripe fruits and is extracted for use in jams and jellies.

Pepsin: the primary digestive enzyme in the stomach; breaks down proteins into smaller peptide chains.

Peptide: a compound consisting of two or more amino acids linked in a chain. These chains of amino acids are shorter than those in polypeptides.

Perception: the higher-order process of integrating, recognizing, and interpreting complex patterns of sensations.

Perceptual illusions: perceptions that are inaccurate representations of sensory stimuli.

Peripheral nervous system (PNS): includes all the nerves outside the brain and spinal cord.

Peritoneal cavity: the space in between the organs in the abdominal cavity and the abdominal wall.

Peritoneum: the connective tissues that cover the internal organs in the abdomen.

Peristalsis: relaxation and contraction of muscles in the small intestine that propels food through the digestive tract.

Peritonitis: inflammation of the peritoneum, the thin tissue that lines the inner wall of the abdomen and covers most of the abdominal organs.

Pesticide: a substance used to destroy insects harmful to crops.

Phagocytosis: the process through which a phagocyte consumes a pathogen or other cellular material.

Phospholipids: a class of lipids that are a major component of cell membranes.

Phytonutrients: a substance found in certain plants which is believed to be beneficial to human health and prevent various diseases. Unlike vitamins and minerals, phytonutrients are not known to be essential to life.

Phytoplankton: microscopic plants and algae that live in water.

Plasma membrane: the biological membrane that separates the interior of all cells from the outside environment.

Plasmid: a DNA molecule that is separate from and can replicate independently from the chromosomal DNA.

Plus-end: end of microtubules oriented toward the axon terminal.

Plus-end directed motors: molecular motors that travel toward the plus-end of microtubules, and thus carry cargo from the cell body to the axon terminal.

Polymer: ‘poly’ means ‘many’, ‘mer’ means ‘part’. A substance consisting chiefly or entirely of a large number of similar units bonded together.

Polypeptide: a polymer of a large number of amino acids bonded together in a chain. Forms a protein.

Positive symptom: symptom in which one acquires an abnormal behavior.

Postsynaptic cell: the neuron located after the synapse, and thus receiving the signal.

Postsynaptic potentials: small changes in voltage (membrane potential) due to the binding of neurotransmitter.

Potential energy: the energy a body has because of its position relative to others, electric charge and other factors.

Prefrontal cortext (PFC): part of the frontal lobe that receives emotional and motivational input and is necessary for logical decision making.

Preoptic nucleus (PON): nucleus in the hypothalamus that signals the pineal gland to release melatonin when light levels fall.

Presynaptic cell: the neuron located before the synapse, and thus sending the signal.

Primary structure: the characteristic sequence of amino acids forming a protein or polypeptide chain.

Prokaryotes: organisms that lack a nucleus or other membrane-bound organelles. Bacteria are prokaryotes.

Protective factors: factors in a person’s life that reduce the risk of developing addiction.

Proteins: a class of compounds consisting of one or more amino acids. Found in legumes, meats and eggs.

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Quaternary structure: the structure formed by the interaction of two or more proteins or polypeptide chains.

Quinine: an antimalarial drug derived from the bark of the cinchona tree. It is usually taken orally, but in severe cases, it is provided to a patient through the bloodstream.

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R chain: a generic name for a side chain on a molecule. In amino acids the R chain can be short or long.

Rapid eye movement (REM) sleep: the stage of sleep characterized by rapid eye movements, loss of muscle tone, and EEG waves similar to those seen when awake.

Receptor: a molecule in or on a cell that receives chemical signals.

Receptor-gated ion channels: ion channels that open or close in response to the binding of a neurotransmitter.

Relapses: recurring drug use after periods of abstinence.

Relative refractory period: the period after the absolute refractory period during which a higher-than-normal amount of stimulation is necessary to make a neuron fire.

REM sleep behavior disorder: disorder in which the paralysis that normally occurs during sleep is incomplete or absent, allowing people to ‘act out’ their dreams.

Remissions: drug free periods.

Reservoir: a reservoir typically harbors the infectious agent without injury to itself and serves as a source from which other individuals can be infected.

Residue: a small amount of something that remains after the main part has gone.

Resting membrane potential: the steady membrane potential of a neuron at rest, usually about -70 mV.

Retrograde transport: movement of materials from axon terminals to the cell body.

Retrovirus: a virus that incorporates into the host cells’ DNA

Reuptake: a process that involves transport of neurotransmitter out of the synaptic cleft by the same cell that released the neurotransmitter.

Reward pathway: neural circuit that plays an important role in rewarding and reinforcing the effects of behaviors, including the ventral tegmental area, Nucleus accumbens, and prefrontal cortex.

Risk factors: factors in a person’s life that increase the risk of developing addiction.

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Saltatory conduction: conduction of the action potential from one node of Ranvier to the next along a myelinated axon.

Saturated bond: a type of chemical bond that has the maximum number of hydrogen atoms.

Secondary structure: the local three-dimensional structure of different portions of a protein or polypeptide chain.

Segmented genome: a genome that is in more than one piece. For example, the human genome is segmented into twenty-three pieces called chromosomes.

Seizure focus: specific area of the brain where partial seizures begin.

Self-administration method: a test used to measure the abuse potential of a drug by allowing an animal to give itself doses of the drug.

Sensation: immediate and basic experience generated as sensory stimuli fall on our sensory systems.

Serological testing: testing blood.

Shiga toxin: is found on a plasmid and produces a protein that kills intestinal epithelial cells.

Sialic acid: a monosaccharide (sugar) used as a building block for molecules in cells throughout the body.

Simple partial seizures: partial seizure without the loss the consciousness.

Sodium-potassium pump: active transport mechanism that pumps sodium (Na+) ions out of neurons and potassium (K+) ions into neurons.

Soluble fiber: dietary fiber that is water-soluble. This fiber type can absorb water and bile in the intestine to form a gel, making you feel full.

Soma: another name for the cell body.

Somatic nervous system: part of the PNS that controls voluntary movement.

Spirochete: spiral-shaped bacterium.

Sporozite: the form of plamsmodium that replicates in the liver.

Sputum: mucus and other matter that can be brought up from the lungs.

Stabilizer: a substance that prevents or inhibits a chemical reaction, usually added to maintain a certain texture.

Starch: a carbohydrate consisting of a large number of glucose monomers joined together by alpha bonds. Produced in most green plants as energy storage.

Stem cell: a cell that can divide into more cells or change (differentiate) into other cell types.

Sterile: free of biological contaminants, including bacteria, viruses, fungi, and parasites.

Stimulants: the class of drugs that increase the activity of the central nervous system.

Sugar: a class of water-soluble, crystalline, typically sweet-tasting carbohydrates. Glucose, fructose and sucrose are all sugars.

Suppurative: pus forming.

Suprachiasmatic nucleus (SCN): nucleus in the hypothalamus that controls that circadian cycles of various body functions.

Synapse: junction between two neurons, consisting of a small gap across which impulses pass from one neuron to another.

Synaptic cleft: small gap in the synapse that separates the presynaptic cell from the postsynaptic cell.

Synaptic transmission: the conduction of messages from one neuron to another across a synapse.

Synaptic vesicles: small spherical membranes that store neurotransmitters and release them into the synaptic cleft.

Systemically: affecting the whole body.

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Tertiary structure: the overall three-dimensional structure of a protein or polypeptide chain.

Tetanus: a syndrome characterized by uncontrolled muscle contractions, caused by a neurotoxin produced by Clostridium tetani.

Thickener: a substance added to a liquid to make it firmer.

Threshold: the level of depolarization needed to generate an action potential.

Tolerance: decreased response to a drug as a direct result of repeated drug exposure.

Toxin: a poisonous substance produced within the cells of living organisms.

Trans: a shape of chemical bond where two types of structures lie on opposite sides of the bond. Will make the bond have the shape of a Z, creating a straight molecule.

Transcription factors: proteins that bind to DNA and influence the expression of particular genes.

Transmission: the passing of a communicable disease from one host to another.

Traveler’s diarrhea: common to international travelers, it is a relatively mild diarrhea that can be caused by any number of pathogens, that is most often transmitted by poor sanitation.

Triglyceride: the main constituent of natural fats and oils. High levels in the blood indicate a high risk for cardiovascular disease.

Tropsim: the affinity of a particular virus for a particular cell type because of the presence of a specific receptor.

Tuberculin skin test: a test for tuberculosis infection.

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Uncoating: a process whereby the viral capsid is removed.

Unsaturated bond: a type of chemical bond in which one or more hydrogen atoms is missing.

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Vector: an organism that transmits a pathogen from reservoir to host.

Ventral tegmental area (VTA): brain region containing dopamine neurons that form connections with nucleus accumbens and prefrontal cortext.

Ventricles: the spaces inside the hollow brain and spinal cord that are gilled with cerebro spinal fluid.

Ventrolateral preoptic nucleus (VLPO): nucleus in the hypothalamus that when active, puts us to sleep.

Virion: a virus particle that includes all of the components of a complete virus.

Virulence: a pathogen‘s ability to infect and cause disease.

Viruses: small acellular (lacking a cell) infectious agents that can replicate only within the cells of living organisms.

Viscosity: a measure of fluidity or stickiness. Honey or pudding is more viscous than water.

Vitamins: compounds that cannot be synthesized by the body but are required for biological reactions.

Voltage-gated channels: channels that open or close in response to changes in voltage across the membrane.

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Water-Soluble: describes a substance that dissolves in water, not fats.

Wernicke’s area: area of the temporal lobe that is critical for understanding language.

White matter: portions of the nervous system that appear white in color because they are composed of myelinated axons.

WHO: World Health Organization

Withdrawal: the condition brought on by the elimination from the body of a drug on which the person has become physically dependent.

Withdrawal symptoms: the condition brought on by the elimination from the body of a drug on which the person has become physically dependent.

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Zoonosis: an infectious disease that can be transmitted from animals to humans.

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