A. Incorrect! The alveolus is where gas exchange takes place. B. Correct! Surfactant is the lipid-rich material that permits lung inflation.

Transcription

1 Toxicology - Problem Drill 13: Respiratory Toxicology No. 1 of The lipid-rich material that decreases surface tension of the alveoli, allowing sacs to inflate properly and remain inflated during breathing, is called. (A) Alveolus (B) Surfactant (C) Asbestos (D) Oxygen The alveolus is where gas exchange takes place. B. Correct! Surfactant is the lipid-rich material that permits lung inflation. Asbestos is a lung toxicant. Oxygen is a gas, not a lipid. Surfactant is a lipid-rich material that decreases surface tension of the alveoli, allowing sacs to inflate properly and remain inflated during breathing. It has detergent-like properties that cause foaming when surfactant comes in contact with a liquid such as water or blood. The correct answer is (B).

2 No. 2 of is another name for the movement of gases, such as oxygen and carbon dioxide, across the alveolar membrane. (A) Ventilation (B) Perfusion (C) Edema (D) Diffusion Ventilation refers to inhalation and exhalation. Perfusion refers to the blood supply received by the lungs. Edema is fluid accumulation. D. Correct! Diffusion is another name for the movement of gases, such as oxygen and carbon dioxide, across the alveolar membrane. The principal function of the lung is gas exchange, which consists of ventilation, perfusion and diffusion. Ventilation takes place when fresh air moves into the upper respiratory tract and into the terminal respiratory units. After gas exchange between air in the lungs and red blood cells, carbon dioxide waste is removed through exhalation. Perfusion refers to the blood supply received by the lungs. The lungs receive the entire cardiac output from the right ventricle in order to oxygenate blood prior to distribution throughout the body. Diffusion refers to the movement of gases across the alveolar membrane that allows for oxygen to trade places with carbon dioxide. The correct answer is (D).

3 No. 3 of is severe inflammation that causes lungs to become larger and overinflated. (A) Emphysema (B) Lung cancer (C) Fibrosis (D) Asthma A. Correct! Emphysema is severe inflammation that causes lungs to become larger and overinflated. Think of a non-cancerous lung injury. Fibrosis causes the lungs to become stiff, not over-inflated. Asthma is airway inflammation characterized by episodes of shortness of breath. Emphysema is characterized by the lungs becoming larger and over-inflated as a result of severe inflammation of the lung tissue. As a result, the gas-exchange surface becomes distended, and the lungs can no longer effectively exchange carbon dioxide for oxygen. The major cause of emphysema is inhalation of cigarette smoke, although other toxicants can also produce this response. Studies in smokers suggest that neutrophil elastases break down lung elastin and cause emphysema. The correct answer is (A).

4 No. 4 of is another name for the process of bringing air into the lungs (inhalation) and expelling air from the lungs (exhalation). (A) Ventilation (B) Perfusion (C) Edema (D) Diffusion A. Correct! Ventilation refers to inhalation and exhalation. Perfusion refers to the blood supply received by the lungs. Edema is fluid accumulation. Diffusion is another name for the movement of gases, such as oxygen and carbon dioxide, across the alveolar membrane. The principal function of the lung is gas exchange, which consists of ventilation, perfusion and diffusion. Ventilation takes place when fresh air moves into the upper respiratory tract and into the terminal respiratory units. After gas exchange between air in the lungs and red blood cells, carbon dioxide waste is removed through exhalation. Perfusion refers to the blood supply received by the lungs. The lungs receive the entire cardiac output from the right ventricle in order to oxygenate blood prior to distribution throughout the body. Diffusion refers to the movement of gases across the alveolar membrane that allows for oxygen to trade places with carbon dioxide. The correct answer is (A).

5 No. 5 of Water solubility is the critical factor determining how far a gas will penetrate the lungs. If a gas is highly soluble, it will. (A) Not penetrate farther than nose. (B) Reach the alveoli. (C) Be taken up by pulmonary blood supply. (D) Distribute evenly throughout the lungs. A. Correct! If a gas is highly soluble, it will not penetrate farther than nose. Think earlier in the respiratory system. Think earlier in the respiratory system. Think earlier in the respiratory system. Within the respiratory tract, the site of deposition defines the pattern of toxicity. Water solubility of the toxicant is the critical factor in determining how deeply a given gas will penetrate into the lung. Gases that are highly soluble, such as sulfur dioxide, do not penetrate farther than the nose and thus are relatively nontoxic. In contrast, relatively insoluble gases, such as ozone and nitric oxide, travel deep within the lungs to reach the alveoli, where they can exert their toxic effects. Very insoluble gases, such as carbon monoxide, efficiently pass through the respiratory tract and are taken up by the pulmonary blood supply for distribution throughout the boy. The correct answer is (A).

6 No. 6 of determines the region where a particle will deposit within the respiratory tract. (A) Water solubility (B) Diffusion (C) Edema (D) Perfusion (E) Particle size Water solubility is the critical factor determining how far a gas, not a particle, will penetrate the lungs. Diffusion is another name for the movement of gases, such as oxygen and carbon dioxide, across the alveolar membrane. Edema is fluid accumulation. Perfusion refers to the blood supply received by the lungs. E. Correct! Particle size determines the region where a particle will deposit within the respiratory tract. Particle size is the critical factor that determines the region of the respiratory tract where a particle or an aerosol will be deposited. Larger particles are usually distributed in the upper air passages, while smaller particles can move all the way to the alveoli. In contrast, aerosols tend to disperse throughout the airway irrespective of size. The correct answer is (E).

7 No. 7 of is a pesticide that causes rapid, extensive lung injury through continuous cycling to create reactive oxygen species. (A) Monocrotaline (B) Bleomycin (C) Cyclophosphamide (D) Paraquat Monocrotaline is a naturally occurring product found in grains, honey and herbal teas. Bleomycin is a widely used chemotherapeutic agent used to treat cancer. Cyclophosphamide is a widely used anticancer and immunosuppressive agent. D. Correct! Paraquat is a pesticide that causes rapid, extensive lung injury through continuous cycling to create reactive oxygen species. Paraquat is a widely used herbicide used to kill a wide range of grasses and weeds within minutes of application. When ingested by humans, paraquat causes rapid, extensive lung injury. In those who survive the acute phase of toxicity, there are long-term, progressive and eventually fatal lung lesions. Paraquat toxicity is due to accumulation within the cells of the lungs, where it continuously cycles from oxidized to reduced states, creating reactive oxygen species and depleting cellular NADPH in the process. The correct answer is (D).

8 No. 8 of Asbestos causes a rare form of lung cancer called. (A) Mesothelioma (B) Squamous cell carcinoma (C) Adenocarcinoma (D) Small cell carcinoma A. Correct! Asbestos causes a rare form of lung cancer called mesothelioma. Squamous cell carcinoma originates from airway epithelial cells in the center of the lung. Adenocarcinoma originates from airway epithelial cells in the periphery of the lung. Small cell carcinoma is a different type of lung cancer. Exposure to asbestos is linked to development of a rare form of cancer known as mesothelioma. There can be an extremely long latent period (up to 40 years or more) between exposure to asbestos and the development of mesothelioma. The correct answer is (A).

9 No. 9 of There are at least 69 known carcinogens in. (A) Paraquat (B) Bleomycin (C) Cyclophosphamide (D) Cigarette smoke Paraquat is a pesticide that causes rapid, extensive lung injury through continuous cycling to create reactive oxygen species. Bleomycin is a widely used chemotherapeutic agent used to treat cancer. Cyclophosphamide is a widely used anticancer and immunosuppressive agent. D. Correct! There are at least 69 known carcinogens in cigarette smoke. The greatest risk factor for lung cancer is exposure to tobacco smoke. It has been well-established that smokers have a times greater risk of developing lung cancer than nonsmokers and that smoking interacts in an additive or synergistic manner with other risk factors for lung cancer (such as asbestos). Out of the estimated 4000 or so compounds found in cigarette smoke, there are approximately 69 known carcinogens. These include polycyclic aromatic hydrocarbons (PAHs) such as nitrosamines, heterocyclic amines, formaldehyde, and benzene, pesticides such as DDT and vinyl chloride and metals such as nickel, chromium, cadmium and lead. The correct answer is (D).

10 No. 10 of is a technique that allows the study of the inner contents of the lungs. (A) Diffusion capacity (B) Tissue biopsy (C) Microdissection (D) Pulmonary lavage Diffusion capacity is a measure of pulmonary function. Tissue biopsies study the tissue surrounding the inner space of the lungs. Microdissection is an in vitro technique to study lung tissue surrounding the inner space of the lungs. D. Correct! Pulmonary lavage is a technique that allows the study of the inner contents of the lungs. One can also study the inner contents of the lungs by washing them in a process called pulmonary lavage. The insides of the lungs are washed with small volumes of isotonic saline, which washes out a variety of cells, including macrophages and monocytes, as well as several types of enzymes and protein. Pulmonary lavage allows measurement of apparent changes in the permeability of the gas-exchange barrier. The correct answer is (D).