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Ref ID: 21122
Ref Type: Book
Authors: Kormondy, Edward J.
Brown, Daniel E.
Title: Fundamental of human ecology
Date: 1998
Place of Publication: New Jersey
Publisher: Prentice Hall
Abstract: Chapters 2,3,6,7,11,14,16 \uCHAPTER 6\u \bEnvironmental stress\b is an external condition that causes a potentially injurious change in biological systems \bAdaptation\b is the process of adjustment and change in an organism that enables it to survive, reproduce, and function \bLaw of the Minimum\b implies that an organism (and a population) is not stronger than the wekest link in its ecological chain of requirements. \bPhenotypic pasticity\b are observable biological changes that induced by the environmnet. \bAcclimatization\b is a froms of phenotypic pasticity that enables an individual to compensate over period of days or weeks to a complex of environmental factors, including, for instance, seasonal changes. Acclimatization are reversible while developmental adaptations are not. \bSingle-Stressor Model\b Allows for differentiation of the macroenvironment and microenvironment. In the model, the macroenvironment is seen as modified by a "buffer" made up of behavioral and cultural adpatations of human groups. This cultural buffer transforms the macroenvironment to a microenvironment. Human physiological adaptation is thus a response to the microenvironment and as constituting a second buffer with the macroenvironment. Deviation from homeostatsis leads to a change in adaptive processes in degree or type of strategy used.. The model permits identification of environmental stresses that have a significant impact on human groups, including possible selective effects. A limitation of the single-stressor model is its consideration of only one stressor at a time. Human populations are in fact faced with numerous stressors simulataneously, and thier responses to a given stressor may be partly determined by their concomitant responses to other stressors. \uCHAPTER 7\u \bHeat Exchange\b is by means of conduction, convection, radiation, and evaporation \bCold macroenvironments\b Mountainous areas, artic and temperate regions, other factors include wind speed "wind chill" and humidity (because of its effect on evaporation rates) \bCultural adaptations to the cold\b Cultural adaptations include various means of increasing insulation, scheduling high activity for situations in whihc cold conditions cannot be avoided, sharing body heat, generating warmth through the use of heated foods and water and through fire, and using various means to avoid getting wet. Clothing, Bedding, Housing, fire Activity Scheduling Alcohol and other agents - short-term benefits
metabolized quickly, but long-term cause increase in superficial blood floor. Chewing coco leaves leads to mild blood constriction in fingers and toes
may cause frostbite. \uBiological response to cold\u Bergmann and Allen's Rule Facial form- while flat faces are not necessarily more adaptive for cold conditions, it is generally thought immediately adjacent to veins, allowing heat exchange between the blood in the arteries and veins. \uMetabolic Adaptation\u Shivering- induced by skin receptors that are activated by the lowering of skin temperatures. The skins thermal receptors are linked to the hypothalamus in the brain where the central temperature regulating center is located. Shivering can lead to a doubling or tripling of the basal metabolic rate. It also leads to an increase in heat loss because peripheral blood vessels dilate Brown fat- Nonshivering thermogenesis, brown adipose tissue, which releases norepinepherine, a hormone that causes a general increase in the basal metabolic rate particularly due to changes in lipid metabolism \uDemographic effects\u Infants high at risk
some occupational groups at risk \uHot-Dry Macroenvironments\u SEE Hanna and Brown (1983) notes \bChapter 9\b Malnutrition and Infectious Disease \uProtein-Calorie Malnutrition\u deficiency in the energy content of food, measured in kcal, and/or a deficiency in protein. \uProtein deficiency\u Is a general form of amino acid deficiency, with different types of malnutrition depending on whihc amino acids are in short supply. Because the end result of all forms of amino acid deficiency is the inability to produce proteins, the biological effects of the different types of amino acid deficiency are the same. Populations with a predominately vegetarian diet are more likely to be exposed to protein malnutrition unless the diet is sufficiently broad that it includes plants with different amino acid proportions. A good example of food mixing is in Mexico with corn and beans. Protein deficiency malnutrition is often a disease associated with weaning. By the age of five growth rates decline, reducing the severity of protein malnutrition problems Effects of chronic conditions include: lowered birth weight, slowed/ceased growth, skeletal and reproductive development slows, delayed menarche Most severe effect is Kwashiorkor which is severe muscle atrophy, growth failure, skin rash, edema, and in some cases depigmentation of skin or hair, reduced immune system \uProtein-Calorie\u While a diet with sufficient calories but insufficient protein is possible, the reverse is not. Hence, a diet with insufficient calories is also deficient in amino acids. "A negative energy balance" - epxending more than taking in. Glygogenesis (the synthesis of glycogen from the simple sugar glucose) Glycogenolysis (the breakdown of glycogen into glucose) Anabolism (tissue buildup) is stimulated by insulin which is a major controller of skeletal muscle breakdown. Cori Cycle- an adaptive process for conserving glucose, involves a switch to anaerobic metabolism in muscle tissue, with glucose bren down into lactose instead of into the smaller molecules of carbon dioxide and water. The positive effect of this cycle is that the energy that is used in glucose synthesis comes from lipid (fat) metabolism. Thus, the cycle employs energy from the body's fat deposits to be used to recycle glucose for use in muscle and brain metabolism. Negetive effects include great loss of body weight, loss of fat stores, loss of body protein, particularly from skeletal muscle mass, extended birth labor (up to 5 hrs on average), apathy and inactivity. Effects of protein-calorie malnutrition are much greater in children, in cases of severe malnutrition leading to a disease termed \bmarasmus\b. Children suffering from this combine the muscle depletion of Kwashiorkor with a loss of most body fat. \uVitamin A deficiency\u Is required for normal functioning of certain epithelial cells of the body. Deficiency can cause night blindness, dry skin, and cloudiness of the cornea. Can lead to blindness. The deficiency is common among poor farmers who do not have enough land to grow vegetables other than cereal staples. It is often associated with protein-caloric malnutrition. Vitamin A is found in green and yellow vegetables, milk, butter, and cheese
can be synthesized from beta-carotene. \uThiamine (Vitamin B\-1\-deficiency\u Function in the metabolism of carbohydrates, and therefore is particularly problematical where diets are low in the vitamin but high in carbohydrates. Food in most foods, deficiencies are found in populations that rely on rice as a major part of the diet. Ironically, if is more common among well-off peasants because purchasing highly milled rice. The vitamin is located predominately in the pericarp portion of the rice surrounding the grain. The milling process removes this portion, as does excessive soaking of the rice. In developed countries, it is primarily a deficiency of alcoholism, as they typically fail to eat properly. Severe deficiency causes BeriBeri which causes cardiovascular and neurological problems since carbohydrate metabolism is important in making glucose available for muscle and brain tissue. \uNiacin (Vitamin B\-3\-\u Is in low supply in corn. The amino acid tryptophan can be converted into niacin in the body, but it is also realtively deficient in maize. Can cause Pellagra which causes skin probelms that resemble sunburns, and can turn into more severe dermatitis, diarrhea, and neurological symptoms. \uVitamin C\u Hominoids, one type of bat, and guinea pigs are among the only mammals that cannot synthesize ascorbic acid in their bodies. Asorbic acid functions in the biochemical pathway in whihc the amino acid proline is converted into collagen. Collagen in turn functions as a chemical that binds together cells i the body tissues, notably cartilage, bone, and teeth. Is associated with poor wound healing and the breakdown of old scars from past healing. The result is widespread hemorrhaging, sore gums and joints. Can lead to Scurvey and is found in population with no access to fresh fruits, especially citrus, or vegetables such as tomatoes and green peppers. \uVitamin D\u Need for the absorption of calcium from the intestine and calcium's subsequent use in the formation of bone and teeth. The childhood deficiency disease associated is Rickets. Charactized by bowing of the bones, delayed tooth eruption and defective development of tooth enamel. Osteomalacia is the term for the same disease but in adults, and is most commonly in pregnant and lactating women. \uIron deficiency\u Most of the body's iron is used in the protein hemoglobin, which carries oxygen and carbon dioxide in the blood. A severe iron deficiency can lead to Anemia as red blood cell production becomes defective due to lack of hemoglobin. \iIodine deficiency\i Iodine is animportant chemical compoent of thyroid hormones and a deficiency of the mineral can lead to reduced thyroid function. The thyriod gland often swells in an attempt to increase hormone production This condition is termed Goiter. Prevelance is highest in mountain populations, including those in the Alps and New Guinea. \uCalcium deficiency\u The mineral is important for formation of bones and teeth during development and for their maintenance. Calcium is also important for the normal functioning of the nervous system. Found in dark green leafy vegetables. Can lead to slow bone growth and to Osteoporosis, with the latter particularly prevalent in the postmenopausal women. \uFood versus Nutrients\u \bFood\b is a culturally defined concept, including all substances considered edible. \bNutrients are chemicals needed by the body and include carbohydrates, lipids, protein, vitamins, and minerals.\b There are many factors which influencing people's choices in food, including environmental ones. Alternatively, during rapid culture change foreign goods may attain prestige. Many decisions about what is edible are based on cultural conventions- that is, cultural definitions of what constitutes food may not always be based on objetive criteria about what is the best nutrients. Not all cultural conventions are adaptive, thus important nutrients may be defined as inedible and not utilized. \uInfectious Disease as a Biotic Stressor\u Mortality rate is the number of fatalities due to the disease per population size. Morbidity rate is the number of people suffering from the disease in relation to population size The benefit of using mortality rate-as opposed to morbidity rates- as a quatitiative measure of disease rate is that deaths are commonly well reported, so information can obtained, while many instances ofsickness may go unreported. The disadvantage of using mortality rates is obviously that no all illness result in death. Prevalence rate is defined as the number of cases of the dierase at any given point in time. Incidence rate is the number of new cases that appear during a given period of time. \uHost-parasite relationship\u Natural selection against parsite virulence will occur only i there is an advantage to the parasite to keeping its host alive and well. For parasites that can easily change hosts, there may be no change in virulence over time. \uVector-born disease\u Vectors are the vehicles by which parasites are transferred from an infected to a susceptible host. They most commonly are arthropods, a large biological grouping that includes insects, spiders, and shrimp among others. Vectors can be considered in two groups: mechanical and biological agents. Mechanical agent, the vector simply transfers parasites by external contact (e.g, fly to excrement to foot to parsite deposit). A biological agent, the vector becomes infected (with or without symptoms of its own). \uMalaria\u \iAnopheles\i mosquitoe. P. \ifalciparum\i \uCultural Buffers\u destruction of breeding sites avoidance of high mosquitoe areas sickle-cell trait fava bean consumption nets/screens
Date Created: 7/5/2001