Phases of Toxic Phenomenon Exposure and Absorption Quiz
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Questions and Answers

Which factor is NOT considered to be important in affecting the likelihood of a xenobiotic being absorbed?

  • Route of exposure
  • Concentration of the substance at the site of contact
  • Color of the substance (correct)
  • Chemical and physical properties of the substance

    • What is true about the relationship between exposure dose and absorbed dose for substances injected directly into the body?

  • They are equal (correct)
  • Absorbed dose is higher than the exposure dose
  • Absorbed dose is lower than the exposure dose
  • Absorbed dose depends on the route of exposure

    • Which route is NOT considered a primary route of exposure for xenobiotics to enter the body?

  • Dermal (skin)
  • Gastrointestinal tract
  • Olfactory (nose) (correct)
  • Respiratory system

    • If a xenobiotic is categorized as highly toxic via one route and relatively non-toxic via another, what does this indicate?

    <p>Toxicity can vary based on the route of exposure</p> Signup and view all the answers

    Which is NOT mentioned as a factor that affects absorption of xenobiotics?

    <p>Time of day</p> Signup and view all the answers

    Why must a substance be absorbed to exert an effect on internal organs?

    <p>To cross cellular barriers</p> Signup and view all the answers

    What is the main difference between facilitated diffusion and simple diffusion?

    <p>Facilitated diffusion involves carrier-mediated transport proteins.</p> Signup and view all the answers

    Which process requires cellular energy to move molecules across the membrane?

    <p>Active transport</p> Signup and view all the answers

    In endocytosis, how does the cell take in substances?

    <p>By engulfing them with a section of the cell wall</p> Signup and view all the answers

    What is the importance of active transport in the body?

    <p>To maintain electrolyte balance</p> Signup and view all the answers

    Which type of cells are involved in phagocytosis?

    <p>Lung phagocytes</p> Signup and view all the answers

    How do toxicants absorbed through the skin enter the blood supply?

    <p>By entering lymphatic vessels</p> Signup and view all the answers

    Where are lymph capillaries found in the body?

    <p>In the lymph nodes</p> Signup and view all the answers

    Which type of transport across cell membranes requires cellular energy or assistance?

    <p>Active transport</p> Signup and view all the answers

    What is the main feature of facilitated diffusion in toxicant movement across cell membranes?

    <p>Pores in the membrane needed for passage</p> Signup and view all the answers

    Which factor determines the rate of passive transfer across cell membranes?

    <p>Difference in concentrations across the membrane</p> Signup and view all the answers

    What role does lipid solubility play in the passive transfer of substances across cell membranes?

    <p>Promotes diffusion through lipid portions of the membrane</p> Signup and view all the answers

    What determines a substance's ability to pass through aqueous pores in cell membranes?

    <p>Molecular weight</p> Signup and view all the answers

    In toxicant movement across cell membranes, what is true about large water-soluble molecules?

    <p>They are impeded by lipid portions of the membrane</p> Signup and view all the answers

    For xenobiotics to move within the body, what must they do when passing cell membranes?

    <p>Penetrate multiple cell membranes</p> Signup and view all the answers

    Which body defense mechanism prevents substances from gaining entry into body tissues?

    <p><strong>Cell Membranes</strong></p> Signup and view all the answers

    Which factor affects the distribution of toxicants to tissues primarily due to the volume of blood flowing through a specific tissue?

    <p>Volume of blood flowing through a specific tissue</p> Signup and view all the answers

    What determines the rate of distribution of toxicants to organs or tissues primarily?

    <p>Blood flow</p> Signup and view all the answers

    What does the volume of distribution (Vd) of a toxicant depend on?

    <p>Unbound fraction of the toxicant in plasma</p> Signup and view all the answers

    Why can toxicants bound to plasma proteins not cross capillary walls?

    <p>Due to their high molecular weight</p> Signup and view all the answers

    What are the primary forces responsible for protein-ligand interactions with toxicants in plasma?

    <p>Hydrogen bonding and van der Waals forces</p> Signup and view all the answers

    Why can a compound with a high degree of plasma protein binding appear less toxic than one with less binding?

    <p>Bound compounds are less biologically active</p> Signup and view all the answers

    What is NOT a factor that can influence the distribution of toxicants to tissues?

    <p><strong>Rapid elimination</strong> of the toxicant from the body</p> Signup and view all the answers

    Plasma concentration is high and Vd is low for which type of chemical distribution?

    <p><strong>No tissue distribution</strong></p> Signup and view all the answers

    Protein binding, active transport, and high fat solubility contribute to the selective accumulation of some toxicants where?

    <p><strong>At the site of toxicity</strong></p> Signup and view all the answers

    Which factor can cause protective accumulation of a toxicant if it accumulates at a site other than the target organ?

    <p>Free fraction in plasma increases due to equilibrium</p> Signup and view all the answers

    Which factor can lead to decreased toxicity of a compound in obese individuals compared to lean individuals?

    <p>Rapid mobilization of fat</p> Signup and view all the answers

    What is a common physiological barrier that restricts the entry of toxicants into the central nervous system?

    <p>Presence of glial cell processes</p> Signup and view all the answers

    What effect might short-term starvation have on experimental animals previously exposed to persistent organochlorine insecticides?

    <p>Decreased intoxication symptoms</p> Signup and view all the answers

    Why are lead deposits not considered toxic to bone compared to other substances like fluoride and radioactive strontium?

    <p>Non-dynamic deposition process</p> Signup and view all the answers

    What is a key role of the placental barrier in relation to toxicants?

    <p>Slowing down the diffusion from maternal circulation</p> Signup and view all the answers

    How does the blood-brain barrier restrict the entry of toxicants into the brain?

    <p>Tight junctions between capillary endothelial cells</p> Signup and view all the answers

    Why is storage in bone considered dynamic for toxicants?

    <p>Continuous exchange between bone surface and extracellular fluid</p> Signup and view all the answers

    What can be a consequence of high lipid/water partition coefficient for certain toxicants?

    <p>Enhanced concentration in target organs</p> Signup and view all the answers

    Which factor contributes to the concentration of many chemicals in the liver and kidney compared to other organs?

    <p>Competitive binding of endogenous substances</p> Signup and view all the answers

    What role do astrocytes play in relation to the blood-brain barrier's function?

    <p>Secrete chemical actors that modulate endothelial permeability</p> Signup and view all the answers

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