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60 Cards in this Set
- Front
- Back
Thermoregulation
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the maintenance of body temperature within a range that enables cells to function efficiently
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Conduction
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the direct transfer of thermal motion from an object of warmer temperature to an object of cooler temperature, or between molecules of the body and those of the environment
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Convection
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the transfer of heat by the movement of air or liquid past the surface of a body
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Radiation
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the emission of electromagnetic waves produced by all objects warmer than absolute zero; transfer heat between objects that are not in direct contact
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Evaporation
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the loss of heat from the surface of a liquid that is loosing some of its molecules as gas; evaporation of water has a significant cooling effect on animals
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Ectotherm
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a classification of animals; warms their bodies by absorbing heat from the surroundings
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Endotherm
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a classification of animals; derives most or all of its heat from its own metabolism; most maintain relatively constant temperature despite wide fluctuation in external temperature; energetically expensive
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Vasodilation
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an increase in the diameter of superficial blood vessels; nerves signal the vessels to relax allowing more blood flow; allows more heat to be transferred to the environment
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Vasoconstriction
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reduces blood flow and heat loss by decreasing the diameter of superficial vessels; prompted by neural signaling; restricts heat transfer to the external environment; thermoregulatory technique
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Counter-current heat exchange
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important mechanism for controlling heat loss in many endothermic animals; allows heat transfer to occur from the warmer arteries to the cooler veins; especially prominent in marine endotherms
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Nonshivering thermogenesis
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hormonal triggering of heat production; hormones trigger metabolic heat production rather than that of ATP
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Brown fat
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a tissue found in the neck of some animals that is specialized for rapid heat production; sight of nonshivering thermogenesis in some animals
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Acclimatization
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a physiological response of an animal that allows it to adjust to a new range of environmental temperatures over a period of days or weeks; i.e. seasonal change; may involve changes in internal thermostat settings and may involve cellular adjustments
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Stress-induced proteins
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special protein molecules produced by cells in laboratory cultures when subjected to extreme stressors such as temperature change, rapid pH change, or toxin exposure
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Heat shock proteins
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a type of stress-induced protein synthesized by cultured cells that are subject to rapid and extreme heat change; help maintain the integrity of other proteins that would be denatured by severe heat
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Torpor
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an alternative physiological state in which metabolism decreases and the heart and respiratory system slow down; essentially, body’s thermostat gets turned down
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Hibernation
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long-term torpor in which the body temperature is lowered as an adaptation to winter cold and food scarcity
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Estivation
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summer torpor is characterized by slow metabolism and inactivity
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Osmoregulation
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how an organism regulates solute balance and the gain or loss of water
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Transport epithelium
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a layer or layers of specialized epithelial cells that regulate solute movements; in most animals, transport epithelia are arranged into tubular networks with extensive surface area; molecular structure of plasma membrane determines the kinds of solutes that move across transport epithelia and the direction they move
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Ammonia
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toxic byproduct of metabolism; most aquatic animals secrete ammonia directly because it dissolves easily in water; in fishes it is usually lost as ammonium ion through the gills; unsuitable for waste excretion on land
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Urea
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100,000x less toxic than ammonia; produced in the vertebrate liver by a metabolic cycle that combines ammonia with carbon dioxide; carried to the excretory organs (kidneys) by the circulatory system; by secreted high concentrations of urea, an animal can conserve water
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Uric acid
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can be excreted in a pastelike form with very little loss of water; thousands of times less soluble in water than either ammonia or urea; excreted by birds, reptiles, land snails, etc.
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Osmolarity
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total solute concentration expressed as molarity; often expressed in milliosmoles per liter; isoosmotic refers to two solutions of the same relative osmolarity; hypoosmotic refers to the more dilute solution, hyperosmotic refers to more concentrated solutions
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Osmoconformer
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an animal that does not adjust its internal osmolarity because its internal fluids are isoosmotic with the external environment
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Osmoregulator
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animal that must regulate its internal osmolarity; because its internal fluid or solute is not isoosmotic to the external environment, it must be changed to regulate loss; an energetically costly process
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Stenohaline
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animals that cannot tolerate wide fluctuations in the osmolarity of their body fluids
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Euryhaline
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animals that can survive wide fluctuations in the osmolarity of their internal body fluids
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Anhydrobiosis
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the ability of some aquatic invertebrates living in temporary ponds to lose all their water and survive in a dormant state when their habitat dries up; means “life without water”; cryptobiosis means hidden life; i.e. water bears
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Excretion
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the process by which animals get rid of nitrogenous-containing waste products that are a byproduct of metabolism
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Filtration
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a process by which blood or other body fluids is exposed to a filtering device made of the selectively permeable membrane
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Reabsorption
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selective transport of water and valuable solutes, such as glucose, salts, and amino acids, from the filtrate back into the body fluids; important because of the nonselectivity of filtration
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Secretion
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the process by which solutes are removed from the animal’s body fluid and added to the filtrate
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Protonephridium
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a network of closed tubules lacking internal openings; excretory system in animals such as flatworms and other simple animals; incorporates a flame bulb with a tuft of cilia that the beat and provide a force that draws water and solutes from the interstitial fluid through the flame bulb and into the tubule system; functions mainly in osmoregulation
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Metaniphridium
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a type of tubular excretory system that has internal openings that collect body fluids; exists in most annelids, has osmoregulatory and excretory functions; in earthworms, urine leaves the body through nephridiopores
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Malpighian tubules
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excretory organs of insects and other terrestrial arthropods; tubules that remove nitrogenous wastes from the hemolymph and also function in osmoregulation
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Ureter
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the duct through which urine leaves the kidney and drain into the urinary bladder
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Urinary bladder
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holds urine until it is excreted from the body
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Renal cortex
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the outer anatomical region of the kidney
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Renal medulla
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inner anatomical region of the kidney
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Nephron
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the functional unit of the vertebrate kidney; consists of a single long tubule and a ball of capillaries
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Glomerulus
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a ball of capillaries at one end of the nephron
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Bowman’s capsule
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a capsule that surrounds the glomerulus
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Podocytes
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specialized cells of the Bowman’s capsule that function as a filter; permeable to water and small solutes, but not blood cells or large macromolecules such as proteins
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Proximal tubule
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initial region of the nephron tubule
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Loop of Henle
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a hairpin turn with an ascending limb and a descending limb; major functional region of solute diffusion and water osmosis
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Distal tubule
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final region of the nephron tubule
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Collecting duct
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receives filtrate from many nephrons; empty into the renal pelvis
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Cortical nephrons
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about 80% of the nephron tubules in human kidneys have reduced loops of Henle and are almost entirely confined to the renal cortex
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Juxtamedullary nephrons
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about 20% of the nephrons in the human kidneys that have well developed loops that extend into the renal medulla
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Afferent arteriole
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a branch of the renal artery the subdivides into the capillaries of the glomerulus; supply every nephron with blood
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Efferent arteriole
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convergence of capillaries leaving the glomerulus
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Peritubular capillaries
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a second subdivision of capillaries that intermingle with the proximal and distal tubules of the nephron
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Vasa recta
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capillaries that extend down the loop of Henle, also forming a loop
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Antidiuretic hormone (ADH
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hormone produced in the hypothalamus that is important in osmoregulatory processes; stored and released from the pituitary gland; if blood osmolarity rises about 300 mosm/L, additional ADH is released into the bloodstream
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Juxtaglomerular apparatus (JGA)
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a tissue that helps regulate kidney function; located near the afferent arteriole and supplies blood to the glomerulus, when blood pressure or blood volume in the afferent arteriole drops, the enzyme rennin initiates chemical reactions that convert a plasma protein called angiotensinogen to angiotnesin II
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Angiotensin II
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a peptide converted from angiotensinogen by rennin; increases blood pressure and blood volume in several ways, constricts arterioles, stimulates proximal tubules to reabsorb more NaCl and water, and stimulates adrenal glands to release aldosterone
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Aldosterone
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a hormone released by the adrenal glands that acts on the nephrons’ distal tubules making them reabsorb more Na+ and water
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Rennin-angiotensin-aldosterone system (RAAS)
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a complex feedback circuit that functions in osmotic homeostasis
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Atrial natriuretic factor (ANF)
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a hormone that is opposed to the RAAS; released by the walls of the heart; inhibits the release of renin from JGA, inhibits NaCl absorption by collecting ducts, and reduces aldosterone release from adrenal glands
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