NURS 735 - APPLIED TOXICOLOGY

As a result of completing this module, your learning objectives will be to:

• List and explain the factors that affect absorption of toxic substances across the cell membrane.
• Identify and describe the major functions of the liver.
• Discuss how toxic substances affect the liver.
• Identify and describe the major functions of the kidney.
• Explain the effects of nephrotoxic substances on kidney function.
• Describe the general anatomy of the skin, GI tract, and lungs.
• Explain the characteristics of these tissues that make them susceptible to chemical effects.
• Identify the components of the blood-brain barrier.
• Describe the characteristics of the blood-brain barrier that affect the absorption of toxic substances and how this affects the body.

To guide your understanding of key concepts throughout this module:

• Read chapter 1 from the Timbrell Textbook: and answer questions Q1-Q6. (These questions are for your own self-assessment and are not to be submitted.)
  
• Review the History of Toxicology and Branches of Toxicology Sciences documents. These two links are in PDF format, which may include text or images and require Adobe Acrobat to be viewed and printed. If you need Adobe Acrobat Reader - download and install at adobe products.
  
• Additional support materials on volume of distribution and passive diffusion & active transport.
  There is also a downloadable pdf file with support information pertaining to metabolism.
  

To guide your understanding of key concepts throughout this module:

•  Textbook Readings:

Chapter 2 (Timbrell): Absorption, distribution and excretion

Chapter 3  (Timbrell): Metabolism

At the end of each of these chapters, answer all quiz questions. These questions and answers are for your own benefit; keep them in your notebook but do not post answers to the course Discussion Board (answers are in the back of the book).

• Childrens' susceptibilities:
  Link to guest speaker, Liz Blackburn (US Environmental Protection Agency), who will focus on:
  'Why kids are different than little adults with regard to ADME principles.'

• Visit each of the following ToxTutorial Websites:  

INTRO TO ADME: Introduction to toxicokinetics (i.e., ADME) Organ-specific toxic effects

ABSORPTION: Principles of absorption and exposure Absorption: gastrointestinal route Absorption: pulmonary route Absorption: dermal route Absorption: other routes of exposure

DISTRIBUTION: Distribution: how do chemicals move through the body? Distribution: influence of route of exposure Distribution: structural barriers Distribution: storage sites Kinetic models (i.e., disposition)

ELIMINATION: Principles of excretion (i.e., elimination) Excretion: renal (anatomical/physiological considerations) Excretion: biliary/fecal; enterohepatic recirculation Excretion: pulmonary Excretion: other routes

METABOLISM (biotransformation): Principles of metabolism (i.e., biotransformation) Metabolism: definitions and pathways Metabolism: enzyme localization Metabolism: modifying factors

After looking at the provided resources , please answer the following questions and post your responses in the appropriate threads on the Discussion Board.

Module 2 discussion board assignments: 

#1. Module 2: General Questions. Use the first Module Discussion Board thread to ask/share general questions relevant to the content of Module 2, i.e., ADME. Please include concise "subject" titles in your postings to facilitate easy following of the discussion threads. Based on your assigned textbook chapters and all the hyperlinked ToxTutorials (listed in the table above), be sure you understand all the materials including the following basic principles:

* Anatomical differences between the three primary routes absorption and factors that can alter the rate of absorption.
* Passive diffusion, active transport, volume of distribution.
* Lipophilicity/hydrophobicity and ionization state of a drug or chemical and effect on uptake or transport.
* Factors affecting excretion; routes of excretion.
* Phase I and phase II metabolism; likely route(s) of metabolism for general categories of chemicals; localization of different metabolic enzymes; factors affecting metabolism.

If you are unclear about certain concepts, use the Discussion Board to post specific questions to your classmates.

#2. Module 2: Experiential Contributions. From your own background and experiences, please share with NURS 735 participants one brief case (two or three paragraphs): that discusses a specific drug or toxicant, and how it is taken up, distributed, metabolized and excreted (i.e.,, the ADME). There should be sufficient detail to include the specifics of the drug or toxicant's ADME routes. You can site references. Keep it consise and easy to read. If you cannot readily generate a good example sparked from your own experience, please generate an example based on the abundant, available literature. Your individual contributions will facilitate sharing your collective expertise as well as providing topical examples for this module.