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level: Level 2

Questions and Answers List

C. EXCRETION VS REABSORPTION

level questions: Level 2

QuestionAnswer
C. EXCRETION VS REABSORPTION 1 the REMOVAL OF XENOBIOTICS FROM BLOOD and their RETURN to the EXTERNAL ENVIRONMENT A PHYSICAL MECHANISM 2 A CHEMICAL MECHANISM for ELIMINATING THE TOXICANT.1 Excretion 2 Biotransformation
C. EXCRETION VS REABSORPTION 1 The ROUTE & SPEED of EXCRETION of the toxicant depend largely on the __ 2 These organs, the __ EFFICIENTLY REMOVE HIGHLY HYDROPHILIC CHEMICALS such as ORGANIC ACIDS & BASES.1 Physicochemical Properties 2 Major Excretory Organs— the Kidney and the Liver—
C. EXCRETION VS REABSORPTION (EXCRETION) 1 There are NO EFFICIENT ELIMINATION MECHANISMS for __. If resistant to __, such chemicals are eliminated VERY SLOWLY and tend to ACCUMULATE in the body on repeated exposure 2 THREE INEFFICIENT PROCESSES are available for the elimination of such chemicals: 3 VOLATILE, NONREACTIVE TOXICANTS such as __ DIFFUSE from PULMONARY CAPILLARIES into the __. 1) 1 Nonvolatile, Highly Lipophilic Chemicals. 2 Biotransformation 2) 1 Excretion from the MAMMARY GLAND in breast milk 2 Excretion in BILE 3 Excretion into the INTESTINAL LUMEN from blood. 3) 1 Gases and Volatile liquids 2 Alveoli and are Exhaled
C. EXCRETION VS REABSORPTION (REABSORPTION) 1 Toxicants delivered into the RENAL TUBULES may __ across the tubular cells into the __ This __ INCREASES the INTRATUBULAR CONCENTRATION as well as the RESIDENCE TIME of the chemical by __. 2 REABSORPTION BY DIFFUSION is - Dependent on: __ - Inversely related to: __ 3 because the NONIONIZED MOLECULE is __ soluble. 1) 1 diffuse back, 2 PERITUBULAR CAPILLARIES. 3 Tubular Fluid Reabsorption 4 slowing urine flow 2) 1 Lipid solubility of the chemical, 2 Extent of ionization, - More Ionized = Less Diffusion 3 more lipid
C. EXCRETION VS REABSORPTION (REABSORPTION) 1 Toxicants delivered to the GI tract by __ may be REABSORBED BY DIFFUSION across the INTESTINAL MUCOSA 2 REABSORPTION of COMPOUNDS EXCRETED into the BILE is POSSIBLE ONLY IF they are __. 1 BILIARY, GASTRIC, & INTESTINAL EXCRETION & SECRETION by SALIVARY GLANDS and EXOCRINE PANCREAS 2 LIPOPHILIC enough, are CONVERTED to MORE LIPID SOLUBLE forms in the INTESTINAL LUMEN(TUBE).
D. TOXICATION VS DETOXICATION - (TOXICATION) 1 BIOTRANSFORMATION TO HARMFUL PRODUCTS is called __ 2 With some __, Toxication CONFERS PHYSICOCHEMICAL PROPERTIES that adversely ALTER the MICROENVIRONMENT of biological processes or structures. 1 Toxication or Metabolic Activation 2 Xenobiotics
D. TOXICATION VS DETOXICATION - (TOXICATION) 1 Most often Toxication RENDERS XENOBIOTICS and occasionally other molecules in the body, such as __, REACTIVE toward __ 2 This INCREASED REACTIVITY may be due to conversion into: __. 1 nitric oxide, Endogenous molecules with susceptible functional groups. 2) (1) Electrophiles, (2) Free radicals, (3) Nucleophiles, or (4) Redox active reactants. NERF
D. TOXICATION VS DETOXICATION - (DETOXICATION) What are the different types of DETOXICATION1 Detoxication of Toxicants with No Functional Groups 2 Detoxication of Nucleophiles 3 Detoxication of Electrophiles 4 Detoxication of Free Radicals 5 Detoxication of Superoxide Anion Radical by Superoxide Dismutase, Glutathione peroxidase, and Catalase 6 Detoxication of peroxidase generated free radicals such as chlorpromazine free radical by glutathione 7 Detoxication of Protein toxins
D. TOXICATION VS DETOXICATION - (DETOXICATION) 1 the BIOTRANSFORMATIONS that ELIMINATE THE ULTIMATE TOXICANT or PREVENT its FORMATION. 1 Detoxication
D. TOXICATION VS DETOXICATION - (DETOXICATION) 1 In general, chemicals WITHOUT FUNCTIONAL GROUPS, such as __, are detoxicated in TWO PHASES: __ 2 The Final Product of the 2 phase detoxication is __. 1 Benzene and Toluene. step 1 - hydroxyl or carboxyl (a functional group) is introduced into the molecule step 2 - endogenous acid such as Glucuronic acid, Sulfuric acid, or an Amino acid is added to the functional group by a Transferase. 2 INACTIVE, HIGHLY HYDROPHILIC ORGANIC ACIDS that are readily excreted.
D. TOXICATION VS DETOXICATION - (DETOXICATION) 1 NUCLEOPHILES generally are DETOXICATED by __, preventing peroxidase from catalyzing the conversion of the nucleophiles to __ and the biotransformation of phenols, aminophenols, catechols, and hydroquinones into __. 1 Conjugation at the Nucleophilic functional group, Free radicals, Electrophilic QUININES & QUINONEIMINES.
D. TOXICATION VS DETOXICATION - (DETOXICATION) 1 Generally, detoxication of ELECTROPHILIC TOXICANTS involves __ 2 This reaction occur SPONTANEOUSLY or can be FACILITATED by __. 3 COVALENT BINDING of ELECTROPHILES TO PROTEINS can be regarded as DETOXIFICATION, provided that the protein has __. 1 Conjugation of Nucleophile Glutathione. 2 Glutathione transferases 3 NO critical function and does NOT become harmful.
D. TOXICATION VS DETOXICATION - (DETOXICATION) 1 __ can be converted into much more reactive compounds, its elimination is an IMPORTANT DETOXICATION MECHANISM. 2 __, located in the CYTOSOL (Cu, ZnSOD) and the mitochondria (MnSOD), convert O2 to HOOH 3 Subsequently, HOOH is reduced to water by __. 1) O2 2 Superoxide dismutases 3 Cytosolic Glutathione Peroxidase or Peroxisomal Catalase.
D. TOXICATION VS DETOXICATION - (DETOXICATION) DETOXICATION OF PEROXIDASE GENERATED FREE RADICALS SUCH AS CHLORPROMAZINE FREE RADICAL BY GLUTATHIONE 1 The byproducts are __ and __, from which GSH is regenerated by __. 1 Glutathione thiyl radical (GS• ) Glutathione disulfide (GSSG) Regenerated by: Glutathione reductase (GR)
D. TOXICATION VS DETOXICATION - (DETOXICATION) - Detoxication of Protein toxins 1 __ are INVOLVED IN THE INACTIVATION OF TOXIC POLYPEPTIDES. 2 Venom toxins, such as __, lose their activity. 1 Extra and intracellular proteases 2 α and β bungaratoxin, erabutoxin, and phospholipase