Question 1
| Identify the methods by which toxicants enter the body. Provide a brief description and at least two examples of each. Your response should be at least 250 words in length. You are required to use at least your textbook as source material for your response. All sources used, including the textbook, must be referenced; paraphrased and quoted material must have accompanying citations. | ||||
| Selected Answer: When you think about the methods toxicants can enter the body, three systems are categorized. 1. The respiratory system is where the toxicant primarily attacks the lungs in order to enter the body. It does this in the form of toxic gases, solvents, aerosols and particulates (Richards, 2014). In the respiratory system it can also enter the body through the pulmonary tissue which is highly vascularized. This tissue also has an extremely large surface area for the absorption of toxicants. Examples of the respiratory system are sinusitis and tonsillitis. 2. The gastrointestinal system has a very large surface area that allows an easier way for the toxicants to enter the body. The pH plays a very important role in the absorption of toxicants within the human body (Richards, 2014). This is because the pH varies from one body part to another body part within the human system, therefore the absorption of chemicals is different for the different body parts. Examples of the gastrointestinal system are halitosis and tooth eruption.3. The integumentary system is primarily concerned with the absorption of toxicants in the body through the skin. Since the surface is not large all chemicals can not be absorbed by the skin, although lipid soluble compound are easily absorbed through the skin. Examples of the integumentary system are pompholyx and dermatitis. REFERENCERichards, I., & Bourgeois, M. (2014). Principles and practice of toxicology in public health (2nd ed.). Burlington, MA: Jones and Bartlett. |
Question 2
25 out of 25 points
| List and describe the factors that affect the distribution of a toxicant in the body. Your response should be at least 250 words in length. You are required to use at least your textbook as source material for your response. All sources used, including the textbook, must be referenced; paraphrased and quoted material must have accompanying citations. | ||||
| Selected Answer: The toxicants move inside and outside the human body because of their diffusion. The rate at which toxicants diffuses in and out of the cell membranes primarily depends on several different factors listed below.1. Size of molecule – All chemicals that are lipophilic are easily diffused across the phospholipid bilayer but the water soluble molecules pass across the membrane through aqueous channels (Richards, 2014).2. Molecular charge and degree of ionization – The molecular size and charge of the toxicant determine the net rate of diffusion. Example would be the large molecular size toxicant’s diffusion rate is lower than that of the smaller molecule size toxicants. The degree of ionization is also very important for determining the diffusion rate of the toxicant inside the human body. Uncharged toxic molecules can easily diffuse across the cell membrane while the charge molecules are not easily allowed to diffuse across the cell membrane (Richards, 2014). 3. Water solubility – Water solubility is an important factor in he case of toxicants diffusion into the human hoday. Water solubility determines whether an toxic chemical can enter the human body through your skin or not. If the toxicant does not have higher solubility in water, then the toxicant absorbed by the human body will be lowered. Now if it has a higher solubility level in water, then it can easily be absorbed by the human body. All of this in return will result in higher amounts of toxic absorption. REFERENCERichards, I., & Bourgeois, M. (2014). Principles and practice of toxicology in public health (2nd ed.). Burlington, MA: Jones and Bartlett. |
Question 3
25 out of 25 points
| Identify the methods for toxicant elimination. Choose one of the methods and explain how a toxicant is eliminated.Your response should be at least 250 words in length. You are required to use at least your textbook as source material for your response. All sources used, including the textbook, must be referenced; paraphrased and quoted material must have accompanying citations. | ||||
| Selected Answer: There are several methods for the elimination of toxic chemicals which is absorbed by the human body. Here are the list of methods for the elimination of toxicants.1. Renal elimination2. Fecal elimination3. Pulmonary elimination4. Biotrnsformation5. Elimination through minor routes This rate of elimination of the toxicants within the human body determine the injury caused by the toxicant (Richards, 2014). It can also be very helpful in keeping the body out of danger. Pulmonary elimination – The pulmonary tissue has a large surface area that is provided to the toxicant for absorption. With this there is a need to eliminate that toxic chemical as soon as possible. You have the pulmonary system which is mainly related with your lungs and a important organ of the body. Lungs can be easily used to eliminate the toxic chemicals that are mainly volatile liquids and gases. This is because your lungs take a large amount of air inside and outside each time. This makes it very easy to eliminate volatile liquid and gases through the lungs along the outgoing air. Important factors that determine elimination of chemicals from the lungs include concentration differences between alveolar air and blood plasma, vapor pressure, and plasma solubility (Richards, 2014). Elimination can be easily achieved by simple diffusion of toxic chemicals from the blood to alveolus. As long as the concentration in capillary blood is greater than the concentration of the chemical in the alveolar air. REFERENCERichards, I., & Bourgeois, M. (2014). Principles and practice of toxicology in public health (2nd ed.). Burlington, MA: Jones and Bartlett. |
Question 4
25 out of 25 points
| Explain the importance of phase 2 reactions. Include three examples of phase two reactions and a brief discussion for each.Your response should be at least 250 words in length. You are required to use at least your textbook as source material for your response. All sources used, including the textbook, must be referenced; paraphrased and quoted material must have accompanying citations. | ||||
| Selected Answer: The perfect elimination of the toxicant from the human body is important. This happens when the metabolite meets the required biotransformation which in turn will increase its hydrophilicity (Richards, 2014). When this occurs you will have a significant elimination of the toxicants.Examples of phase 2 reactions and the enzymes that catalyze the transfer of the endogenous chemical include the following: 1. Glucuronide conjugation (UDP-glucuronosyltransferase) – It is an important phase 2 reaction in which the glucose-derived chemical glucuronic acid is added onto the phase 1 metabolite through the enzyme UDPglucuronosyltransferase (uridine 5′-diphosphateglucuronyltransferase). These enzymes are very useful in the detoxification of toxic chemicals. This would include a wide range of xenobiotics, in addition to endogenous compounds such as steroids and bilirubin from the human body. These enzymes are found in the membrane bound in the cell. These enzymes produces a polar metabolite during the process of detoxification which can be easily excreted out of the human body through the urinary system (Richards, 2014).2. Sulfate conjugation (sulphotransferase) – Sulfate conjugation results in highly hydrophilic conjugates that are readily eliminated in the urine (Richards, 2014). Sulfation and glucuronidation are often competing pathways, with the former being the principal pathway at lowers substrate levels. This chemical reaction or the sulfate conjugation is the major phase 2 pathway for the detoxification of phenols from the human body. 3. Glutathione conjugation (glutathione S-transferase) – This phase 2 reaction is mainly responsible for conjugating glutathione, an endogenous tripeptide. The conjugate produced are less toxic when compared to their parents compounds. Glutathione-Stransferase is very important in drug metabolism, and genetic regulation of glutathione-Stransferases is complex and inducible by drugs and xenobiotics. REFERENCERichards, I., & Bourgeois, M. (2014). Principles and practice of toxicology in public health (2nd ed.). Burlington, MA: Jones and Bartlett. |
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