BIOL 1620

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BIOL 1620
2013-02-05 07:00:31
Physiology Evolution

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  1. Nutrition
    • Food being taken in
    • Taken apart
    • Taken up
  2. Essential Nutrients
    • Materials that an animal's cells require but cannot synthesize
    • Include certain minerals and preassembled organic molecules
  3. Essential amino acids
    • An amino acid that an animal cannot synthesize itself and must be obtained from food in prefabricated form
    • Adult humans need 8 different kinds
  4. Essential fatty acid
    An unsaturated fatty acid that an animal needs but cannot make.
  5. Vitamin
    • An organic molecule required in the diet in very small amounts.
    • Many vitamins serve as coenzymes or parts of coenzymes.
    • 13 have been identified for humans
  6. Mineral
    • A simple nutrient that is inorganic and therefore cannot be synthesized in the body.
    • Ex: Iron and sulfur
  7. Malnutrition
    A failure to obtain adequate nutrition. Results from a diet that lacks one or more essential nutrients or consistently supplies less chemical energy than the body requires
  8. Undernutrition 
    A result of a diet that fails to provide adequate sources of chemical energy.
  9. Epidemiology
    the study of human health and disease at the population level.
  10. Ingestion
    • The first stage of food processing in animals.
    • The act of eating
  11. Digestion
    • The second stage of food processing in animals.
    • The breaking down of food into molecules small enough for the body to absorb.
    • Mechanical digestion- chewing
    • Chemical digestion- stomach acid
  12. Enzymatic Hydrolysis
    • Splitting process that breaks down macromolecules by adding water.
    • Polysaccharides and disaccharides spilt into simple sugars.
    • Nucleic acids spilt into nucleotides and their components.
    • Proteins spilt into amino acids.
    • Fats and phospholipids spilt into fatty acids and other components.
  13. Absorption
    The third stage of food processing in animals: the uptake of small nutrient molecules by an organism's body.
  14. Elimination
    • The fourth and final stage of food processing in animals.
    • The passing of undigested material out of the body.
  15. Intracellular digestion
    • Hydrolysis of food inside vacuoles.
    • Begins after a cell engulfs solid food by phagocytosis or liquid food by pinocytosis.
  16. Suspension Feeder (Filter Feeders)
    An aquatic animal, such as a sponge, clam, or baleen whale, that feeds by sifting small organisms or food particles from the water.
  17. Bulk Feeder
    • An animal that eats relatively large pieces of food.
    • Most animals are this.
  18. Substrate Feeders
    • An animal that lives in or on its food source, eating its way through the food.
    • Parasites.
  19. Fluid Feeders
    • An animal that lives by sucking nutrient-rich fluids from another living organism. 
    • Mosquitos, aphids, hummingbirds.
  20. Gastrovascular cavity
    A central cavity with a single opening in the body of certain animals, including cnidarians and flatworms, that functions in both the digestion and distribution of nutrients.
  21. Alimentary canal (complete digestive tract)
    A complete digestive tract, consisting of a tube running between a mouth and an anus.
  22. Peristalsis
    • 1. Alternating waves of contraction and relaxation in the smooth muscles ling the alimentary canal the push food along the canal.
    • 2. A type of movement on land produced by the rhythmic waves of muscle contractions passing the front to back, as in many annelids.
  23. Sphincter
    A ringlike band of muscle fibers that controls the size of an opening in the body, such as the passage between the esophagus and the stomach.
  24. Oral cavity
    The mouth of an animal, where ingestion and mechanical digestion begin.
  25. Salivary Gland
    A gland associated with the oral cavity that secretes substances that lubricate food and begin the process of chemical digestion.
  26. Amylase
    • An enzyme that hydrolyzes starch (a glucose polymer from plants) and glycogen (a glucose polymer from animals) into smaller polysaccharides and the disaccharide maltose.
    • Found in Saliva.
  27. Mucus
    A viscous and slippery mixture of glycoproteins, cells, salts, and water that moistens and protects the membranes lining body cavities that open to the exterior.
  28. Bolus
    A lubricated ball of chewed food that has been made in the oral cavity and for passage down the esophagus. 
  29. Pharynx
    • 1. An area in the vertebrate throat where air and food passages cross.
    • 2. In flatworms, the muscular tube that protrudes from the ventral side of the worm and ends in the mouth.
  30. Esophagus
    A muscular tube that conducts food, by peristalsis, from the pharynx to the stomach.
  31. Epiglottis
    a flap of cartilage that covers the glottis when you swallow.
  32. Glottis
    The vocal cords and the opening between them.
  33. Larynx
    the upper part of the respiratory tract, whose movements directes a bolus into the entrance of the esophagus.
  34. Stomach
    An organ of the digestive system the stores food and performs preliminary steps of digestion.
  35. Gastric Juice
    A digestive fluid secreted by the stomach.
  36. Chyme
    The mixture of partially digested food and digestive juices formed in the stomach.
  37. Protease
    An enzyme in the stomach that digests proteins by hydrolysis.
  38. Pepsin
    An enzyme present in gastric juice the begins the hydrolysis of proteins.
  39. Pepsinogen
    The inactive form of pepsin secreted by chief cells located in gastic pits of the stomach.
  40. Small Intestine
    The longest section of the alimentary canal, so named because of its small diameter compared with that of the large intestine; the principal site of the enzymatic hydrolysis of food and macromolecules and the absorption of nutrients.
  41. Duodenum
    The first section of the small intestine, where chyme from the stomach mixes with digestive juices from the pancreas, liver, and gallbladder as well as from gland cells of the intestinal wall.
  42. Pancreas
    A gland with exocrine and endocrine tissues. The exocrine portion functions in digestion, secreting enzymes and an alkaline solution into the small intestine via a duct; the ductless endocrine portion functions in homeostasis, secreting the hormones in insulin and glucagon into the blood.
  43. Bile
    A mixture of substances that is produced in the liver and stored in the gallbladder; enables formation of fat droplets in water as an aid in the digestion and absorption of fats.
  44. Liver
    A large internal organ vertebrates that performs diverse functions, such as producing bile, maintaining blood glucose level, and detoxifying poisonous chemicals in the blood.
  45. Gallbladder
    An organ that stores bile and releases it as needed into the small intestine.
  46. Villus (plural, villi)
    • 1. A finger-like projection of the inner surface of the small intestine.
    • 2. A finger-like projection of the chorion of the mammalian placenta. Large numbers of villi increase the surface areas of these organs.
  47. Microvillus (plural, microvilli)
    One of many fine, finger-like projections of the epithelial cells in the lumen of the small intestine that increases its surface area
  48. Hepatic Portal Vein
    A large vessel the conveys nutrient-laden blood from the small intestine to the liver, which regulates the blood's nutrient content.
  49. Chylomicron
    A lipid transport globule composed of fats mixed with cholesterol and coated with proteins.
  50. Lacteal
    A tiny lymph vessel extending into the core of an intestinal villus and serving as the destination for absorbed chylomicrons.
  51. Large Intestine
    The portion of the vertebrate alimentary canal (and the last bit of it) between the small intestine and the anus; functions mainly in water absorption and the formation of feces.
  52. Colon
    The largest section of the vertebrate large intestine; functions in water absorption and formation of feces.
  53. Cecum
    • The blind pouch forming one branch of the large intestine.
    • Is important for fermenting ingested material, especially in animals that eat large amounts of plant material.
  54. Appendix
    • A small, finger-like extension of the vertebrate cecum.
    • Contains a mass of white blood cells the contribute to immunity.
  55. Feces
    The wastes of the digestive tract.
  56. Rectum
    The terminal portion of the large intestine, where feces are stored prior to elimination.
  57. Ruminant
    An animal, such as a cow or a sheep, with multiple stomach compartments specialized for an herbivorous diet.
  58. Enteric division
    • A branch of the nervous system that is dedicated to the digestive organs.
    • Regulates the reflexes of digestion as well as peristalsis in the small and large intestines,
  59. Leptin
    A hormone produced by adipose (fat) cells that acts as a satiety factor in regulating appetite.
  60. Heart
    A muscular pump the uses metabolic energy to elevate the hydrostatic pressure of the circulatory fluid (blood or hemolymph). The fluid then flows down a pressure gradient through the body and eventually returns to the heart.
  61. Open Circulatory System
    • A circulatory system in which a fluid called hemolymph bathes the tissues and organs directly and there is no distinction between the circulating fluid and the interstitial fluid.
    • Found in Arthropods and most molluscs.
  62. Hemolymph
    In invertebrates with an open circulatory system, the body fluid that bathes tissues.
  63. Closed Circulatory System
    A circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid.
  64. Blood
    A connective tissue with a fluid matrix called plasma in which red blood cells, white blood cells, and cell fragments called platelets are suspended.
  65. Cardiovascular System
    A closed circulatory system with a heart and branching network of arteries, capillaries, and vents. The system is characteristic of vertebrates.
  66. Artery
    A vessel that carries blood away from the heart to organs throughout the body.
  67. Arteriole
    A vessel the conveys blood between an artery and capillary bed.
  68. Capillary
    A microscopic blood vessel that penetrates the tissues and consists of a single layer of endothelial cells that allows exchange between blood and interstitial fluid.
  69. Capillary Bed
    A network of capillaries in a tissue or organ.
  70. Venules
    A vessel the conveys blood between a capillary bed and a vein.
  71. Veins
    • 1. In animals, a vessel that carries blood toward the heart.
    • 2. In plants, a vascular bundle in a leaf.
  72. Atrium (plural atria)
    A chamber of the vertebrate heart that receives blood from the veins and transfers blood to a ventricle.
  73. Ventricle
    • 1. A heart chamber that pumps blood out of the heart.
    • 2. A space in the vertebrate brain, filled with cerebrospinal fluid.
  74. Single Circulation
    • A circulatory system consisting of a single pump and circuit, in which blood passes from the sites of gas exchange to the rest of the body before returning to the heart.
    • Two chambers; an atrium and ventricle.
    • Bony fishes, rays, and sharks.
  75. Double Circulation
    • A circulatory system consisting of separate pulmonary and systematic circuits, in which blood passes through the heart after completing each circuit.
    • 4 chambers: 2 atria and 2 ventricles.
    • Amphibians, reptiles, and mammals.
  76. Pulmonary circuit
    The branch of the circulatory system that supplies the lungs.
  77. Pulmocutaneous circuit
    A branch of the circulatory system in many amphibians that supplies the lungs and skin.
  78. Systemic Circuit
    The branch of the circulatory system that supplies oxygenated blood to and carries deoxygenated blood away from organs and tissues throughout the body.
  79. Cardiac cycle
    The alternating contractions and relaxations of the heart.
  80. Systole
    The stage of the cardiac cycle in which a heart chamber contracts and pumps blood.
  81. Diastole
    The stage of the cardiac cycle in which a heart chamber is relaxed and fills with blood.
  82. Cardiac output
    The volume of blood pumped per minute by each ventricle of the heart.
  83. Heart Rate
    • The frequency of heart contraction (in beats per minute).
    • A factor that determines cardiac output.
  84. Stroke Volume
    • The volume of blood pumped by a heart ventricle in a single contraction.
    • A factor that determines cardiac output.
  85. Atrioventricular (AV) vavle
    A heart valve located between each atrium and ventricle that prevents a backflow of blood when the ventricle contracts.
  86. Semilunar Valve
    A valve located at each exit of the heart, where the aorta leaves the left ventricle and the pulmonary artery leaves the right ventricle.
  87. Heart Murmur
    A hissing sound that most often results from blood squirting backward through a leaky valve in the heart.
  88. Sinoatrial (SA) node
    A region in the right atrium of the heart that sets the rate and timing at which all cardiac muscle cells contracts; the pacemaker.
  89. Osmoregulation
    Regulation of solute concentrations and water balance by a cell or organism
  90. Excretion
    The disposal of nitrogen-containing (such as the form of ammonia) metabolites and other wasted products.
  91. Osmolarity
    • Solute concentration expressed as molarity.
    • The unit of measurement for osmolarity is milliOsmols per liter (mOsm/L).
    • Seawater = 1,000 mOsm/L (equivalent to a total solute concentration of 1 M)
    • Human blood = 300 mOsm/L
  92. Isoosmotic
    • A condition where two solutions, that are separated by a permeable membrane, have the same osmolarity.
    • Water molecules continually cross the membrane, but at equal rates in both directions.
  93. Hyperosmotic
    • a solution with a greater concentration of solutes than another solution separated by a permeable membrane.
    • Water flows by osmosis from a hypoosmotic solution to a hyperosmotic one.
  94. Hypoosmotc
    • A solution that is more dilute than the one separated by a permeable membrane.
    • Water flows by osmosis from a hypoosmotic solution to a hyperosmotic one.
  95. Osmoconformer
    • An animal that is isoosmotic with its environment. That is it has the same concentration of solutes internally as its environment.
    • All osmoconformers are marine animals.
  96. Osmoregulator
    An animal that controls its internal osmolarity independent of the external environment.
  97. Anhydrobiosis
    • "Life without water"
    • A dormant state involving loss of almost all body water.
    • Invertebrates that live in temporary pools of water has this ability. Ex: tardigrades (water bears)
  98. Transport Epithelium
    • One or more layers of specialized epithelial cells that carry out and regulate solute movement.
    • Typically arranged into complex tubular networks with extensive surface areas.
  99. Ammonia
    • A small, toxic molecule (NH(3)) produced by nitrogen fixation or as a metabolic waste product of protein and nucleic acid metabolism.
    • Most common in aquatic species because a lot of water is needed to expel it.
  100. Urea
    • A soluble nitrogenous waste produced in the liver by a metabolic cycle that combines ammonia with carbon dioxide.
    • Mammals, most adult amphibians, sharks, and some marine bony fishes and turtles mainly excrete this.
    • Low toxicity.
    • Much less water needed to expel than ammonia.
    • Disadvantage is that it takes more energy to expel than ammonia.
  101. Uric acid
    • A product of protein and purine metabolism and the major nitrogenous waste product of insects, land snails, and many reptiles. Uric acid is relatively nontoxic and largely insoluble.
    • Although it takes a considerable amount of energy to produce.
  102. Filtration
    In excretory systems, the extraction of water and small solutes, including metabolic wastes, from the body fluid.
  103. Filtrate
    Cell-free fluid extracted from the body fluid by the excretory system.
  104. Reabsorption
    In excretory systems, the recovery of solutes and water from filtrate.
  105. Secretion
    • The discharge of molecules synthesized by a cell.
    • The discharge of wastes from the body fluid into the filtrate.
  106. Protonephridium
    An excretory system, such as the flame bulb system of flatworms, consisting of a network of tubules lacking internal openings.
  107. Metanephridium
    An excretory organ found in many invertebrates that typically consists of tubules connecting ciliated internal openings to external openings.
  108. Malpighian tubule
    A unique excretory organ of insects that empties into the digestive tract, removes nitrogenous wastes from the hemolymph, and functions in osmoregulation.
  109. Proximal Tubule
    In the vertebrate kidney, the portion of a nephron immediately downstream from Bowman's capsule that conveys and helps refine filtrate.
  110. Aquaporin
    A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane.
  111. Countercurrent Multiplier System
    A countercurrent system in which energy is expended in active transport to facilitate exchange of materials and generate concentration gradients.
  112. Antidiuretic Hormone (ADH)
    A peptide hormone, also know as vasopressin, that promotes water retention by the kidneys. Produced in the hypothalamus and released from the posterior pituitary, ADH also functions in the brain,
  113. Renin-angiotensin-aldosterone system (RAAS)
    A hormone cascade pathway that helps regulate blood pressure and blood volume.
  114. Juxtaglomerular apparatus (JGA)
    A specialized tissue in the nephrons that releases the enzyme renin in response to a drop in blood pressure or volume.
  115. Angiotensin II
    A peptide hormone that stimulates constriction of pre capillary arterioles and increases reabsorption of NaCL and water by the proximal tubules of the kidney, increasing blood pressure and volume.
  116. Aldosterone
    A steroid hormone that acts on tubules of the kidney to regulate the transport of sodium ions (Na+0 and potassium (K+).
  117. Atrial Natriuretic Peptide (ANP)
    A peptide hormone secreted by cells of the atria of the heart in response to high blood pressure. ANP's effects on the kidney alter ion and water movement and reduce blood pressure.
  118. Nerve net
    a weblike system of neurons, characteristic of radially symmetrical animals, such as hydras.
  119. Nerve
    A fiber composed primarily of the bundled axons of PNS neurons.
  120. Reflex
    An automatic reaction to a stimulus, mediated by the spinal cord or lower brain.
  121. Central Canal
    The narrow cavity in the center of the spinal cord that is continuous with the fluid-filled ventricles of the brain.
  122. Ventricle
    • 1. A heart chamber that pumps blood out of the heart.
    • 2. A space in the vertebrate brain, filled with cerebrospinal fluid.
  123. Cerebrospinal Fluid
    Blood-derived fluid the surrounds, protects against infection, nourishes, and cushions the brain and spinal cord.
  124. Gray Matter
    Regions of dendrites and clustered neuron cell bodies within the CNS (Central Nervous System).
  125. White matter
    Tracts of axons within the Central Nervous System (CNS).
  126. Motor System
    An efferent (L. "to carry away") branch of the vertebrate peripheral nervous system (PNS) composed of motor neurons that carry signals to skeletal muscles in response to external stimuli.
  127. Autonomic nervous system
    An efferent branch of the vertebrate peripheral nervous system that regulates the internal environment; consists of the sympathetic, parasympathetic, and enteric divisions.
  128. Sympathetic division
    On of three divisions of the autonomic nervous system; generally increases energy expenditure and prepares the body for action.
  129. Parasympathetic Division
    One of three divisions of the autonomic nervous system; generally enhances body activities that gain and conserve energy, such as digestion and reduced heart rate.
  130. Enteric Division
    One of three divisions of the autonomic nervous system  consists of networks of neurons in the digestive tract, pancreas, and gallbladder; normally regulated by the sympathetic and parasympathetic divisions of the autonomic nervous system.
  131. Neural Plasticity
    The capacity of a nervous system to change with experience.
  132. Short-term Memory
    The ability to hold information, anticipation, or goals for a time and then release them if they become irrelevant.
  133. Long-Term Memory
    The ability to hold, associate, and recall information over one's lifetime.
  134. Long-Term Potentiation (LTP)
    An enhanced responsiveness to an action potential (nerve signal) by a receiving neuron.
  135. Neuron
    A nerve cell; the fundamental unit of the nervous system, having structure and properties that allow it to conduct signals by taking advantage of the electrical charge across its plasma membrane.
  136. Brain
    Organ of the central nervous system (CNS) where information is processed and integrated.
  137. Ganglia (singular, ganglion)
    Clusters (functional groups) of nerve cell bodies in a centralized nervous system.
  138. Central Nervous System (CNS)
    The portion of the nervous system where signal integration occurs; on vertebrate animals, the brain and spinal cord.
  139. Peripheral Nervous System (PNS)
    The sensory and motor neurons that connect to the central nervous system.
  140. Nerve
    A fiber composed primarily of the bundled axons of PNS neurons.
  141. Sensory Neuron
    A nerve cell that receives information from the internal or external environment and transmits signals to the central nervous system.
  142. Interneuron
    An association neuron; a nerve cell within the central nervous system that forms synapses with sensory and/or motor neurons and integrates sensory input and motor output.
  143. Motor Neuron
    An nerve cell that transmits signals from the brain or spinal cord muscles or glands.
  144. Cell body
    The part of a neuron that houses the nucleus and most other organelles.
  145. Dendrite
    One of usually numerous, short, highly branched extensions of a neuron that receives signals from other neurons.
  146. Axon
    A typically long extension, or process, of a neuron that carries nerve impulses away from the cell body toward target cells.
  147. Synapse
    The junction where a neuron communicates with another cell across a narrow gap via a neurotransmitter or an electrical coupling.
  148. Neurotransmitter
    A molecule that is released from the synaptic terminal or a neuron at a chemical synapse, diffuses across the synaptic cleft, and binds to the postsynaptic cell, triggering a response.
  149. Glia (glial cells)
    Cells fo the nervous system that support, regulate, and augment the functions of neurons.
  150. Membrane Potential
    The difference in electrical charge (voltage) across a cell's plasma membrane due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances.
  151. Resting Potential
    The membrane potential characteristic of a nonconducting excitable cell, with the inside of the cell more negative than the outside.
  152. Ion Channel
    A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient.
  153. Equilibrium Potential (Eion)
    The magnitude of a cell's membrane voltage at equilibrium; calculated using the Nernst equation.
  154. Gated Ion Channel
    A gated channel for a specific ion. The opening of closing of such channels may alter a cell's membrane potential.
  155. Hyperpolarization
    A change in a cell's membrane potential such that the inside of the membrane becomes more negative relative to the outside. Hyperpolarization reduces the chance that a neuron will transmit a nerve impulse.
  156. Depolarization
    A change in a cell's membrane potential such that the inside of the membrane is made less negative relative to the outside. For example, a neuron membrane is depolarized if a stimulus decreases its voltage from the resting potential of -70 mV in the direction of zero voltage.
  157. Graded Potential
    In a neuron, a shift in the membrane potential that has an amplitude proportional to signal strength  and that decays as it spreads.
  158. Action Potential
    An electrical signal that propagates (travels) along the membrane of a neuron or other excitable cell as a nongraded (all-or-none) depolarization.
  159. Voltage-gated Ion Channel
    A specialized ion channel that opens or closes in response to changes in membrane potential.
  160. Threshold
    The potential that an excitable cell membrane must reach for an action potential to be initiated.
  161. Refractory Period
    The short time immediately after an action potential in which the neuron cannot respond to another stimulus, owing to the inactivation voltage-gated sodium channels.
  162. Myelin Sheath
    Wrapped around the axon of neuron, an insulating coat of cell membranes from Schwann cells or oligodendrocytes. It is interrupted by noes of Ranvier, where action potentials are generated
  163. Oligodendrocyte
    A type of glial cell that forms insulating myelin sheaths around the axons of neurons in the central nervous system (CNS).
  164. Schwann Cell
    A type of glial cell that forms insulating myelin sheaths around the axons of neurons in the peripheral nervous system.
  165. Nodes of Ranvier
    Gap in the myelin sheath of certain axons where an action potential may be generated. In saltatory conduction, an action potential is regenerated at each node, appearing to "jump" along the axon from node to node.
  166. Saltatory Conduction
    Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane
  167. Ligand-gated ion channel
    A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule (ligand), allowing or blocking the flow of specific ions, also called an ionotropic receptor.
  168. Excitatory Postsynaptic Potential (EPSP)
    An electrical change (depolarization) in the membrane of a postsynaptic cell caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor, makes it more likely for a postsynaptic cell to generate an action potential.
  169. Temporal Summation
    A phenomenon of neural integration in which the membrane potential of the postsynaptic cell in a chemical synapse is determined by the combined effect of EPSPs or IPSPs produced in rapid succession.
  170. Spatial Summation
    A phenomenon of neural integration in which the membrane potential of the postsynaptic cell is determined by the combined effect of EPSPs or IPSPs produced nearly simultaneously by different synapses.
  171. Acetylcholine
    One of the most common neurotransmitters; functions by binding to receptors and altering the permeability of the postsynaptic membrane to specific ions, either depolarizing or hyperpolarizing the membrane.
  172. Glutamate
    An amino acid that functions as a neurotransmitter in the central nervous system (CNS).
  173. Gamma-Aminobutyric Acid (GABA)
    An amino acid that functions as a CNS neurotransmitter in the central nervous system of vertebrates.
  174. Biogenic amine
    A neurotransmitter derived from an amino acid.
  175. Norepinephrine
    A catecholamine that is chemically and functionally similar to epinephrine and acts as a hormone or neurotransmitter; also known as noradrenaline.
  176. Dopamine
    A neurotransmitter that is catecholamine, like epinephrine and norepinephrine.
  177. Serotonin
    A neurotransmitter, synthesized from the amino acid tryptophan, that functions in the central nervous system (CNS).
  178. Neuropeptide
    A relatively short chain of amino acides that serves as a neurotransmitter.
  179. Endorphin
    Any of several hormones produced in the brain and anterior pituitary that inhibit pain perception.
  180. Sensory Reception
    The detection of a stimulus by sensory cells.
  181. Sensory Receptor
    An organ, cell, or structure within a cell that respods to specifci stimuli from an organism's external or internal environment.
  182. Sensory Transduction
    The conversion of stimulus energy to change in the membrane potential of a sensory receptor cell.
  183. Receptor Potential
    An initial response of a receptor cell to a stimulus, consisting of a change in voltage across the receptor membrane proportional to the stimulus strength.
  184. Transmission
    The passage of a nerve impulse along axons.
  185. Perception
    The interpretation of sensory system input by the brain.
  186. Amplification
    The strengthening of stimulus energy during transduction.
  187. Sensory adaptation
    The tendency of sensory neurons to become less sensitive when they are stimulated repeatedly.
  188. Mechanoreceptor
    A sensory receptor that detects physical deformation in the body's environment associated with pressure, touch, stretch, motion, or sound.
  189. Chemoreceptor
    A sensory receptor that responds to a chemical stimulus, such as a solute or an odorant.
  190. Electromagnetic receptor
    A receptor of electromagnetic energy, such as visible light, electricity, or magnetism.
  191. Thermoreceptor
    A receptor stimulated by either heat or cold.
  192. Nociceptor
    A sensory receptor that responds to noxious or painful stimuli; also called a pain receptor.
  193. Statocyst
    A type of mechanorceptor that functions in equilibrium in invertebrate by use of statoliths, which stimulate hair cells in relation to gravity
  194. Statolith
    • 1. In plants, a specialized plastid that contains dense starch grains and may play a role in detecting gravity.
    • 2. In invertebrates, a dense particle that settles in response to gravity and is found in sensory organs that function in equilibrium.
  195. organ of Corti
    The actual hearing organ of the vertebrate ear, located in the floor of the cochlear duct in the inner ear; contains the receptor cells (hair cells) of the ear.
  196. Hair cell
    A mechanosensory cell that alters output to the nervous system when hairlike projection on the cell surface are displaced.
  197. Round window
    In the mammalian ear, the point of contact where vibrations of the stapes create a traveling series of pressure waves in the fluid of cochlea.
  198. Utricle
    In the vertebrate ear, a chamber in the vestibule behind the oval window that opens into the three semicircular canals.
  199. Saccule
    In the vertebrate ear, a chamber in the vestibule behind the oval window that participates in the sense of balance.
  200. lateral line system
    A mechanoreceptor system consisting of a series of pores and receptor units along the sides of the body in fishes and aquatic amphibians; detects water movements made by the anima itself and by other moving objects.
  201. Photoreceptor 
    An electromagnetic receptor that detects the radiation known as visible light.
  202. Compound eye
    A type of multifaceted eye in insects and crustaceans consisting of up to several thousand light-detecting, focusing ommatidia.
  203. Ommatidium (plural, ommatidia)
    One of the facets of the compound eye of arthropods and some polychaeteworms.
  204. Single-lens eye
    The camera-like eye found in some jellies, polychaete worms, spiders, and many molluscs.
  205. Pupil 
    The opening in the iris, which admits light into the interior of the vertebrate eye. Muscles in the iris regulate its size.
  206. Iris
    The colored part of the vertebrate eye, formed by the anterior portion of the choroid.
  207. Lateral inhibition
    A process that sharpens the edges and enhances the contrast of a perceived image by inhibiting receptors lateral to those that have responded to light.
  208. Optic chiasm
    The place where the two optic nerves meet and axons representing distinct sides of the visual field are segregated from one another before reaching the brain.
  209. Lateral geniculate nucleus
    One of a pair of structures in the brain that are destination for most of the ganglion cell axons that form the optic nerves
  210. Primary visual cortex
    the destination in the occipital lobe of the cerebrum for most of the axons from the lateral geniculate nuclei.
  211. Fovea
    The place on the retina at the eye's center of focus, where cones are highly concentrated.