Human Anatomy: Jejunum and Ileum Quiz
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Questions and Answers

What are the primary sites for the absorption of nutrients and drugs in the digestive system?

  • Jejunum and ileum (correct)
  • Pancreas and liver
  • Stomach and colon
  • Mouth and esophagus

    • What is primarily absorbed in the colon?

  • Vitamins and minerals
  • Fats and lipid-soluble vitamins
  • Water and ions (correct)
  • Carbohydrates and proteins

    • What cycle characterizes the process of gastric emptying?

  • Circadian rhythm cycle
  • Interdigestive migrating myoelectric complex (correct)
  • Gastric secretion cycle
  • Intestinal phase cycle

    • Which phase of the interdigestive migrating myoelectric complex is the most quiescent?

    <p>Phase I</p> Signup and view all the answers

    How long does Phase II of the interdigestive migrating myoelectric complex last?

    <p>30 – 45 minutes</p> Signup and view all the answers

    What characterizes Phase III of the gastric emptying process?

    <p>Intense contractions and peristaltic waves</p> Signup and view all the answers

    What is the approximate duration of the entire cycle of the interdigestive migrating myoelectric complex?

    <p>1.5 – 2 hours</p> Signup and view all the answers

    Which regions are involved during Phase III of the gastric process?

    <p>Proximal and distal gastric regions</p> Signup and view all the answers

    What was the primary method used to prepare chitosan-based microspheres for tetracycline loading?

    <p>Chemical crosslinking with glyoxal</p> Signup and view all the answers

    What was the approximate size that dosage forms should exceed to remain in the stomach?

    <p>13 mm</p> Signup and view all the answers

    What percentage of non-crosslinked microspheres remained in the stomach after 2 hours?

    <p>10%</p> Signup and view all the answers

    Which approach is mentioned as a method to retain dosage forms in the stomach?

    <p>Increasing size above the pylorus diameter</p> Signup and view all the answers

    After 2 hours, what percentage of crosslinked microspheres remained in the fasted stomach?

    <p>17%</p> Signup and view all the answers

    Why is it desirable to design dosage forms with an initially small size?

    <p>To facilitate swallowing</p> Signup and view all the answers

    What is one reason mentioned for significant variability regarding the cutoff size for dosage forms in the stomach?

    <p>Significant inter-individual variations</p> Signup and view all the answers

    What effect did the crosslinked microspheres have on tetracycline concentration in the stomach?

    <p>Higher concentration than in solutions</p> Signup and view all the answers

    What factor was found to significantly influence mucoadhesion in drug delivery systems?

    <p>Surface charge of the resin</p> Signup and view all the answers

    Which ion-exchange resin did not exhibit the same mucoadhesive characteristics as colestyramine?

    <p>Amberlite IRP-69</p> Signup and view all the answers

    What was the main objective of the oral delivery system developed by Schmitz et al.?

    <p>To target the gastric mucosa for low molecular-weight heparin</p> Signup and view all the answers

    In the gastric transit study, what was observed about the HEC formulations after 4 hours?

    <p>They could not be observed in the gastric lumen</p> Signup and view all the answers

    Which material was used as a mucoadhesive carrier in the study conducted by Hejazi and Amiji?

    <p>Thiolated polycarbophil</p> Signup and view all the answers

    How did the drug release profiles of the formulations compare over 4 hours?

    <p>They showed nearly constant release rates</p> Signup and view all the answers

    What method was used to prepare tetracycline-loaded chitosan microspheres?

    <p>Ionic precipitation</p> Signup and view all the answers

    What role does the coating of colestyramine with ethylcellulose play in its drug delivery potential?

    <p>It reduces the drug delivery effects</p> Signup and view all the answers

    What is a significant feature of the systems developed by Desai and Bolton?

    <p>They consist of biodegradable materials that maintain integrity temporarily.</p> Signup and view all the answers

    What is a major risk associated with size-increasing systems?

    <p>They may obstruct the pylorus.</p> Signup and view all the answers

    How did the amount of agar used in the tablets developed by Desai and Bolton compare to traditional methods?

    <p>It was remarkably low at 2% per tablet.</p> Signup and view all the answers

    What role does the oil play in the moulded agar gel tablet?

    <p>It prevents air from escaping due to its hydrophobicity.</p> Signup and view all the answers

    How does the performance of floating tablets depend on the stomach's condition?

    <p>It is independent of the filling state of the stomach.</p> Signup and view all the answers

    What observation was made regarding saliva levels of the model drug theophylline?

    <p>Saliva levels remained relatively constant over 24 hours.</p> Signup and view all the answers

    What is a disadvantage of size-increasing drug delivery systems?

    <p>They can obstruct the pylorus.</p> Signup and view all the answers

    What characteristic makes the oil suitable for use in the floating tablet system?

    <p>It has a hydrophobic nature that retains air.</p> Signup and view all the answers

    What is a primary function of high-density drug delivery systems?

    <p>To use weight as a retention mechanism</p> Signup and view all the answers

    Why might high-density systems not be suitable for certain therapies?

    <p>They are not effective for large doses of drugs.</p> Signup and view all the answers

    Which component is part of the subcoat in the described drug delivery system?

    <p>Cellulose acetate phthalate</p> Signup and view all the answers

    What type of materials are used to create the hollow core in the described delivery system?

    <p>Hard gelatin capsules or polystyrene foam</p> Signup and view all the answers

    What does the density of the drug delivery system need to be compared to gastric juice for effective retention?

    <p>Greater density than gastric juice</p> Signup and view all the answers

    What was reported about the effectiveness of high-density systems in extending gastric residence time?

    <p>No successful approaches have been described.</p> Signup and view all the answers

    What is the outer coating of the drug delivery system made of?

    <p>Drug-containing EC/hydroxypropyl methylcellulose (HPMC)</p> Signup and view all the answers

    Which of the following is a potential limitation of high-density drug delivery systems?

    <p>Limited to only high-density drugs</p> Signup and view all the answers

    Study Notes

    Absorption in the Gastrointestinal Tract

    • Jejunum and ileum are primary sites for nutrient and drug absorption.
    • Colon primarily absorbs water, ions, and certain drugs due to prolonged residence time.

    Gastric Emptying and Motility

    • Gastric emptying is regulated by the interdigestive migrating myoelectric complex, cycling every 1.5 to 2 hours.
    • Four phases of gastric motility:
      • Phase I: lasts 45-60 minutes, minimal contractions.
      • Phase II: lasting 30-45 minutes, features increasing intensity of contractions.
      • Phase III: occurs for 5-15 minutes, involves strong contractions and peristaltic waves (housekeeper waves).

    Drug Delivery Systems

    • Mucoadhesion plays a critical role in prolonging gastric residence time.
    • Colestyramine exhibits promising mucoadhesive characteristics with significant potential for drug delivery to the gastric mucosa.

    Development of Drug Delivery Forms

    • Tetracycline-loaded chitosan microspheres show enhanced gastric retention times through ionic precipitation and crosslinking.
    • Crosslinked microspheres retain 17% of the drug in the stomach after 2 hours, compared to 10% retention in non-crosslinked forms.
    • Optimal dosage size for retention in the stomach should exceed 13 mm in diameter.

    Design Considerations for Drug Delivery

    • Systems should be initially small for easy swallowing but expand in size once ingested to prolong gastric residence.
    • Biodegradable materials are preferred for drug delivery systems to ensure they degrade after desired use.

    Floating Drug Delivery Systems

    • High-density devices rely on weight for retention in the stomach, settling below the pylorus.
    • Floating systems with hollow cores offer potential for low-dose drugs but may not be adequate for high doses.
    • Certain systems have shown relative independence from the stomach's filling state regarding performance and drug release rates.

    Research Innovations

    • Moulded agar gel tablets with entrapped oil for density reduction are designed to float in gastric fluids.
    • Two-layer coated density-controlled systems contribute to enhanced gastric retention, although challenges remain for large-dose therapies.

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    Description

    Test your knowledge on the jejunum and ileum, which are crucial for nutrient and drug absorption in the human body. This quiz explores their functions and the absorption processes that occur in the colon.

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