Path Book: Chapter 7 Environmental and Nutritional Diseases pg. 268-287 Flashcards
What is an environmental disease?
disorders caused by exposure to chemical or physical agents in the ambient, workplace, and personal environments, including diseases of nutritional origin.
Climate change is expected to have a serious negative impact on human health by increasing the incidence of a number of diseases, including:
- Cardiovascular, cerebrovascular, and respiratory diseases, all of which will be exacerbated by heat waves and air pollution.
- Gastroenteritis, cholera, and other food- and water- borne infectious diseases, caused by contamination as a consequence of floods and disruption of clean water supplies and sewage treatment, after heavy rains and other environmental disasters
- Vector-borne infectious diseases, such as malaria and dengue fever, due to changes in vector number and geographic distribution related to increased tempera- tures, crop failures and more extreme weather variation (e.g., more frequent and severe El Niño events)
- Malnutrition, caused by changes in local climate that disrupt crop production. Such changes are anticipated to be most severe in tropical locations, in which average temperatures may already be near or above crop tolerance levels; it is estimated that by 2080, agricultural productivity may decline by 10% to 25% in some developing countries as a consequence of climate change.
What is Toxicology?
the science of poisons. It studies the distribution, effects, and mechanisms of action of toxic agents. More broadly, it also includes the study of the effects of physical agents such as radiation and heat.
What are Xenobiotics?
exogenous chemicals in the environment that may be absorbed by the body through inhalation, ingestion, or skin contact
Most solvents and drugs are _____.
lipophilic, which facilitates their transport in the blood by lipoproteins and penetration through lipid components of cell membranes.
What are the phases of xenobiotic metabolism?
In phase I reactions, chemicals can undergo hydrolysis, oxidation, or reduction. Products of phase I reactions often are metabolized into water-soluble compounds through phase II reactions of glucuronidation, sulfation, methylation, and conjugation with glutathione (GSH). Water-soluble compounds are readily excreted.
The most important cellular enzyme system involved in phase I reactions is the _____.
cytochrome P-450 system
Where is the cytochrome P450 system located?
primarily in the endoplasmic reticulum (ER) of the liver but also present in skin, lungs, and gastrointestinal (GI) mucosa and in practically every organ.
What is a possible byproduct of metabolism?
production of reactive oxygen species (ROS), which can cause cellular damage
What are some things that impact P450 efficacy?
1) Genetic polymorphisms
2) Dietary practices (fasting, etc.)
3) Smoking or alcohol
In the United States, the Environmental Protection Agency (EPA) monitors and sets allowable upper limits for what six pollutants?
sulfur dioxide, CO, ozone, nitrogen dioxide, lead, and particulate matter.
How does ozone exposure damage the body?
major impact on the lungs. it participates in chemical reactions that generate free radicals, which injure the lining cells of the respiratory tract and the alveoli.
T or F. Low levels of ozone don’t impact people
Low levels of ozone may be tolerated by healthy persons but are detrimental to lung function, especially in those with asthma or emphysema, and when present along with particulate pollution
Sulfur dioxide, particles, and acid aerosols are emitted mainly by what processes?
coal- and oil-fired power plants and industrial processes burning these fuels.
Of these, particles appear to be the main cause of morbidity and death. Particles less than 10 μm in diameter are particularly harmful. Why?
since when inhaled they are carried by the airstream all the way to the alveoli before there is any mechanism to contain/eliminate them
By contrast, larger particles are removed in the nose or are trapped by the mucociliary “escalator” and as a result are less dangerous.
What happens when small particulate matter reaches the alveoli?
They are phagocytosed by macrophages and neutrophils, causing the release of mediators and inciting an inflammatory reaction.
How does CO cause toxicity?
CO is a systemic asphyxiant that kills by binding to hemoglobin and preventing oxygen transport. Hemo- globin has a 200-fold greater affinity for CO than for O2.
What does CO interaction with hemoglobin result in?
Carboxyhemoglobin that is incapable of carrying oxygen.
Systemic hypoxia appears when the hemoglobin is ___ to ___ saturated with CO, and unconsciousness and death are probable with 60% to 70% saturation.
20% to 30%
Can Chronic (low level inhalation over a long time) poisoning by CO kill you? As opposed to rapid influx of CO as in most accidental death and suicides (aka acute poisoning)?
Yes, CO toxicity develops because carboxyhemoglobin, once formed, is very stable. As a result, with low-level persistent exposure to CO, carboxyhemoglobin may accumulate to a life-threatening concentration in the blood. The slowly developing hypoxia can insidiously evoke widespread ischemic changes in the brain
Can people chronically exposed to CO recover once the source is eliminated?
With cessation of exposure to CO, the patient usually recov- ers, but there may be permanent neurologic damage.
sometimes impairments of memory, vision, hearing, and speech may remain.
How is CO poisoning diagnosed?
The diagnosis of CO poisoning is based on detection of high levels of carboxyhemoglobin in the blood.
How would ‘acute’ CO poisoning appear in light skin people?
In light-skinned people, it is marked by a characteristic generalized cherry- red color of the skin and mucous membranes, a color imparted by carboxyhemoglobin.
What are some common indoor pollutants?
1) Cigarette and wood smoke
2) Radon
3) Bioaerosols
