PPE 497 Final Chapter Studyguide
PPE 497 Final Chapter Studyguide PPE 497
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This 11 page Study Guide was uploaded by Paige Seavey on Monday December 14, 2015. The Study Guide belongs to PPE 497 at Syracuse University taught by Brutsaert in Fall 2015. Since its upload, it has received 78 views. For similar materials see Physiology of exercise in Physical Education at Syracuse University.
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Date Created: 12/14/15
Chapter 12: T emperature Regulation 12/13/2015 ▯ Homeotherms= animals that regulate their own core body temperature The maintenance of a constant body temperature requires that heat loss must match the rate of heat production Hemeotherms use a strategy of a ‘furnace’ rather than a ‘refrigerator’ to help keep body at a constant temperature Goal of temperature regulation is to maintain a constant core temperature and thus prevent overheating or overcooling During exercise, body temperature is regulated by making adjustments in the amount of heat that is lost Important component in circulatory system because it has a high capacity to store heat When body is attempting to lose heat blood flow is increased to the skin Sufficient gradient between overall body temperature The core of the body (abdominal, heart, lungs etc.) may be 20 degrees higher than the outer shell of the body Measurements of deep body temperature can be accomplishes through devices such as mercury thermometers, or ingestible core temperature pills Rectal temperature can be used to estimate changes in deep-body temperature Temperature near the ear have been found to be a good measurement of brain temperature Skin temperature can be measured by placing temperature sensors on skin in various locations The body produces internal heat due to normal metabolic processes o At rest/sleep heat production is low, at exercise high Heat production in the body can be classified as: o Voluntary(exercise o Involuntary (shivering or biomechanical heat production caused by secretion of hormones such as thyroxine and catecholamines) Body is at most 20-30% efficient, 70-80% of the energy expended during exercise appears as heat Heat loss occurs in 4 processes o Radiation o Conduction o Convection o Evaporation ▯ Radiation= heat loss in the form of infrared rays Transfer of heat from the surface of one object to the surface of another with no physical contact ▯ Conduction= the transfer of heat from the body to the molecules of cooler objects in contact with its surface ▯ Convection= form of conductive heat loss in which heat is transmitted to either air or water molecules in contact with the body A fan moving large quantities of air across the skin ▯ Evaporation= heat is transferred from the body to water on the surface of skin When water gains enough heat it turns into water vapor Most important means of heat loss Dependent of 3 factors o Temperature and relative humidity o Conductive currents around the body o The amount of skin surface exposed to the body The body loses 0.58 k/cal of heat for each ml of water that evaporates ▯ Specific heat= the amount of heat energy required to raise body temperature depends on the size of the individual and characteristic of body tissue Refers to the amount of heat energy required to raise 1 kilogram of body tissue by 1 degree Celsius The specific heat for the human body is 0.83 k/cal ▯ Anterior hypothalamus= deals with an increase in body heat ▯ Posterior hypothalamus= responsible for reacting to a decrease in body temperature ▯ Heat index= measure of how hot it feels when relative humidity is added to the actual air temperature ▯ Hyperthermia= due to fluid loss causes a high core temperature and heat injury Exercise performance is impaired in hot environments Causes dehydration causes central nervous system impairment Accelerates muscle fatigue and impairs exercise performance ▯ Acclimation= the reversible physiological adaptation to changes in the environmental conditions ▯ Acclimatization= refers to adaptation to a new climatic condition (changes in temperature or altitude) Individuals of all ages are capable of acclimating to a hot environment End result of heat acclimation is a lower heart rate and core temperature during submaximal exercise Key aspect of heat acclimation is an earlier onset of sweating and an increase in the sweat rate Research indicates that an important part of heat acclimation includes the cellular production of heat shock proteins in the skeletal muscle fibers and all other cells in the body ▯ Hypothermia= a large decrease in core temperature Individuals with a high percentage of body fat have an advantage of lean individuals when it comes to cold tolerance Hands exposed to cold rather become numb due to the reduction in rate of neural transmission and reduced blood flow due to vasoconstriction 3 major adaptations occur when humans are exposed to cold temperatures o reduction in mean skin temperature, leads to shivering o cold individuals maintain a higher mean hand-and-foot temperature during cold exposure o improved ability to sleep in cold environments ▯ The three principles of training are: Overload Specificity Reversibility ▯ Overload= the fact that a system (cardiovascular) or tissue (skeletal muscle) must be exercised at a level beyond which it is accustomed in over for a training effect to occur System gradually adapts to overload Typical variables include intensity, duration and frequency of exercise ▯ Reversibility= indicates that the fitness gains by exercising at an overload are quickly lost when training is stopped and the overload is removed ▯ Specificity= refers to the effect that exercise training is specific to the muscles involved in that activity, the fiber types recruited, the principal energy system involved (aerobic vs. anaerobic), the velocity of contraction, and the type of muscle contraction (concentric, eccentric, isometric) Types of adaptations occurring in muscle as a result of training ▯ Maximal aerobic power (vo2)= a reproducible measure of the capacity of the cardiovascular system to deliver oxygenated blood to a large muscle mass involved in dynamic work Endurance training programs that increase vo2 max involve dynamic exercise using a large muscle mass (swimming, running, cycling) for 20-60 minutes per session, 3-5 times per week with an intensity between 50%-85% vo2 max The extremely high vo2 max possessed by male and female elite athletes are likely the genetic gift of a large cardiovascular capacity and high percentage of slow muscle fibers Researchers indicate that the response of the individual to the effect of a training program is also genetically determined ▯ Stroke Volume= the amount of blood ejected from the heart with each beat and is equal to the difference between end diastolic volume (EDV) and end systolic volume (ESV) Months of training can result in a small decrease in maximal heart rate ▯ End Diastolic Volume (EDV)= an increase in EDV results in a stretch of the left ventricle and a corresponding increase in cardiac contractibility via the Frank-Starling mechanism Plasma volume increases with endurance training Bradycardia= a slow resting heart rate that occurs following endurance training ▯ Cardiac Contractibility= the strength of the cardiac muscle contraction when the fiber length (EDV),afterload, and heart rate remain constant ▯ Afterload= refers to the peripheral resistance against which the ventricle is contracting as it tries to push blood into the aorta Afterload is important because when the heart contracts against a high peripheral resistance, stoke volume will be reduced In young sedentary subject about 50% of the increase in vo2 max due to training is related to an increase in maximal stoke volume and 50% is due to an increase in arteriovenous difference ▯ The ability to perform prolonged, submaximal work is dependent on the maintenance of homeostasis during the activity ▯ Endurance training results in a more rapid transition from rest to steady-state exercise, a reduced reliance on the limited liver and muscle glycogen stores, and numerous cardiovascular and thermoregulatory adaptations that assist in maintaining homeostasis ▯ Endurance training-induced in fiber type and capillarity ▯ Endurance training increases mitochondrial content in skeletal muscle fibers One population of mitochondria rests immediately beneath the sarcolemma and the second and larger group (80%) is dispersed around the contractile proteins Increased number of mitochondria improve a muscle fibers capacity to oxidize both carbohydrates and fats ▯ Plasma glucose= primary fuel of the nervous system and is the majority of hormonal changes associated with fasting or exercise that are aimed at maintaining blood glucose levels ▯ The transport of FFA (Free fatty acids) into muscle intramuscular fat provides about 50% of lipid oxidized during exercise and plasma FFA provide the rest ▯ The transport of FFA from the Cytoplasm to the mitochondria a key step in FFA transport into the mitochondria involves both carnitine palmitoyltransferase (CPT-A) and fatty acid translocase (FAT) CPT-1 and FAT work together to increase FFA entry into the mitochondria ▯ Mitochondrial oxidation of FFA the increase in mitochondria number increase the enzymes involved in fatty-acid beta-oxidation Results in an increased rate at which acetylCoA molecules are formed from FFA for entry to the Krebs cycle, where citrate is formed ▯ Endurance training improves muscle antioxidant capacity Free radicals are a chemical species molecules that contain and unpaired electron around their outer orbital; because of this unpaired electron, radicals are highly reactive and can interact with cellular components to damage proteins, membranes and DNA Endurance training increase endogenous antioxidants in trained muscles and these changes protect muscle fibers against free- radical mediated damage and fatigue during prolonged endurance exercise High intensity exercise training can increase the buffering capacity of the exercised muscles Endurance training does not increase muscle buffering capacity, but regular endurance training results in less disruption of blood pH ▯ Regardless of whether the training program, is endurance exercise or resistance exercise, the exercise induced adaptation that occurs in the muscle fibers is a result of an increase in the amount of specific proteins A single bout of endurance exercise is insufficient to produce large changes in proteins within a muscle fiber Skeletal muscle is a very adaptable tissue that responds to exercise training ▯ Mechanical stretch= when muscles contract, the mechanical force placed on the muscle fiber can trigger signaling processes to promote adaptation Example: passive stretching of a muscle fiber stimulates several biomechanical signaling pathways ▯ Calcium= an important signaling mechanism in cells Free calcium in the cytoplasm can activate numerous enzymes and proteins Once activated, calmodium-dependent kinase can indicate a signaling cascade in muscle fibers that contributes to muscle adaptation to exercise training ▯ Free radicals= exercise results in the production of free radicals and other oxidants in active skeletal muscles Important because radicals signals are crucial for muscle adaptation in exercise training Example: free radical production during exercise can activate nuclear factor kappa B and mitogen-activated kinase ▯ Phosphate/ ▯ muscle energy levels= muscular exercise accelerates ATP consumption in the working muscle and increases the ration of AMP/ATP in muscle fibers Increasing AMP/ATP ratio can initiate numerous downstream signaling events in skeletal muscle fibers AMPK= is important signaling molecule that is activated during exercise due to changes in muscle fiber phosphate/energy levels P38= an important signaling molecule that is activated in muscle fibers during endurance exercise PCG-I= activated by endurance exercise and is considered the master regulator of mitochondrial biogenesis in the cells Calmodulin= activated during exercise in an intensity-related manner Calciuneurin= is a phosphatase activated by increases in cytosolic calcium and participates in several adaptive responses in muscle including fiber growth/regeneration and the fast to slow fiber type transition that occurs as a result of exercise training IGF-l/Akt/mTOR= is a signaling pathway that plays a very important role in the regulation of muscle growth resulting in the regulation of muscle growth resulting from resistance training NFkB= is a transcriptional activator that can be activated by free radicals that are produced in contracting muscles ▯ Pheripheral feedback is the idea that reflexes in working muscles might control or “drive” cardiovascular or pulmonary systems in proportion to the metabolic rate originated in the early 1900’s ▯ The biomechanical changes in muscle due to endurance training influence the heart rate and ventilator responses to exercise ▯ The reduction in “feedback” from chemoreceptors in the trained muscle and a decreased need to recruit motor unites to accomplish an exercise task results in reduced sympathetic nervous system, heart rate, and ventilation responses to submaximal exercise ▯ After stoppage of exercise training, VO2 max begins to decline quickly and can decrease by -8% within 12 days after cessation of training and by almost 20% after 84 days of training The decrease in VO2 max with the cessation of exercise is due to both a decrease in maximal stoke volume and a decrease in oxygen extraction ▯ Resistance training-induced increases in skeletal muscle size ▯ Hyperplasia= an increase in the total number of muscle fibers with a specific muscle ▯ Hypertrophy= an increase in muscle fiber cross-sectional area is regarded as the primary means to increase muscle size during long-term strength training Increases in strength due to short-term resistance training are largely the result of changes in the nervous system where as gains in strength in the long-term training program are due to an increase in size of muscle Prolonged periods of resistance training can promote a fast-to-slow shift in muscle fiber types Rapid muscular adaptations occur as a result of strength training in previously trained individuals Resistance training: o Improves the antioxidant capacity of the trained muscle fibers o Increases the synthesis of contractile proteins in muscle therefore resulting in an increase in the cross-sectional area of the fiber o Results in parallel increase in muscle fiber cross-sectional area and increased numbers of myonuclei Stoppage of resistance training: o Loss of muscular strength and muscle atrophy ▯ Neural Factors= in has been proposed that concurrent strength and endurance training impairs strength development because of neural factors Concurrent training impairs motor unit recruitment therefore decreases muscle force production ▯ Low muscle glycogen content= successive bouts of either strength or endurance training can produce chronically lo levels of muscle glycogen ▯ Overtraining= the imbalance between training an recovery ▯ Depressed protein synthesis= concurrent resistant and endurance exercise bouts could result in impaired protein synthesis following resistance exercise training ▯ ▯ Dietary Guidelines for Americans= how to best meet nutritional standards and those associated with vitamins and minerals Current recommendations for the distribution of calories in food include a broad range: carbohydrates 45-65%, fats: 20-35% and proteins: 10-35% ▯ Dietary Reference Intakes (DRIs)= an umbrella term encompassing specific standards for dietary intake ▯ Recommended Dietary Allowance (RDA)= the average daily nutrient intake level sufficient to meet the nutrient requirement of nearly all healthy individuals in a particular group Adequate Intakes (AI)= based on observed or experimentally determined approximations or estimates of nutrient intake by a group of healthy individuals Tolerable Upper Intake Level (UL)= highest average daily nutrient intake level that is likely to pose no risk of health effect to most individuals Estimated Average Requirement (EAR)= average daily nutrient intake level estimated to meet the requirement of half the health individuals in a particular group Estimated Energy Requirement (EER)= average dietary energy intake that is predicted to maintain energy balance in a healthy adult of a defined age, gender, weight, height and level of physical activity Daily Value (DV)= standard used in nutritional labeling o Based on nutritional standards o Serving size, calories etc. ▯ 6 classes of nutrients: Water Vitamins Minerals Carbohydrates Fats Proteins ▯ Water= essential for life, body is made up of 50-75% Under normal conditions body loses 2500 ml/day of water ▯ Vitamins= organic catalysts involved in metabolic reactions Needed in small amounts and are not used up in he metabolic reactions Fat soluble vitamins= A,D,E,K. Can be stored in large quantities in the body o Longer to get a deficiency compared to water soluble Water soluble vitamins= C,B. Most are involved in energy metabolism ▯ Minerals= the chemical elements other than carbon, oxygen, hydrogen, and nitrogen associated with the structure and function of the body Minerals are divided into two classes: o Major minerals= calcium, phosphorus, magnesium, sulfur, sodium, potassium and chloride o Trace elements= iron, iodine, fluoride, zinc, selenium, copper, cobalt, manganese, molybdenum, arsenic, nickel and vanadium Calcium= combine with phosphorus to create teeth and bones o Osteoporosis= lack of calcium causing loss of bone Iron= majority found in hemoglobin in red blood cells Sodium= directly involved in the maintenance of the resting membrane potential and the generation of action potential in nerves and muscles ▯ Carbohydrates= carbohydrates and fats are the major source of energy in the average American diet Sugars and starches= carbohydrate is a major energy source for all tissues and a crucial source for two: red blood cells and neurons Dietary fiber= indigestible portion of food ▯ Fats= dietary lipids include triglycerides, phospholipids, and cholesterol Americans consume too much saturate fat ▯ Proteins= has same energy density as carbohydrate but is not viewed as a primary energy source Important because it contains 9 essential amino acids ▯ Approaches to meet dietary guidelines include: USDA Food Patterns= identifies daily amounts of foods with a focus on nutrient density from the five major groups (grains, vegetables, proteins, fruits, dairy) Dietary Approaches to Stop Hypertension (DASH)= developed to deal with hypertension, by both preventing it and to lower blood pressure ▯ Obesity is a major problem in our society, related to hypertension, elevated sebum cholesterol and adult onset diabetes ▯ Methods to measure body composition: Isotope dilution Photon Absorptiometry Potassium-40 Hydrostatic (underwater weighing)* Dual Energy X-Ray Absorptiometry (DEXA) Near Infared Interactance (NIR) Radiography Ultrasound Nuclear Magnetic Resonance (NMR) Total Body Electrical Conductivity (TOBEC) Bioelectrical Impedance Analysis (BIA)* Air Displacement Plethysmography* Skinfold Thickness* ▯ BMI uses a simple ratio of weight-to-height squared to classify individuals as being normal weight, overweight, or obese. ▯ Body composition assessment can be based on four component (mineral, water, protein and fat) Four-component model is most accurate Body fat percentage value has about + 2.0-2.5% error due to biological variation of fat-free mass ▯ Subcutaneous fat can be sampled as skinfold thickness, and a sum of skinfolds can be converted to a body fat percentage with formulas derived from the relationship of the sum of the skinfolds to a body composition standard based on a two, three or four component model ▯ Recommended range of body fatness for healthy men is 8-22% and for ▯ women 20-35% values for fitness are 5-15% and 16-28% respectively ▯ Obesity is associated with an increased mortality from cardiovascular disease and some types of cancer Obesity is characterized as 30kg of fat mass ▯ Dieting, exercise and weight control are key ▯ Nutrient balance exists for both protein and carbohydrates Excess intake is oxidized and is not converted to fat ▯ The ratio of the Food Quotient (FQ) to the Respiratory Quotient (RQ) provides good information about the degree to which an individual is in nutrient balance ▯ Diets with a high fat-to-carbohydrate ratio are linked to obesity Nutrient balance for fat can be most easily achieved with a low-fat diet ▯ Basal Metabolic Rate (BMR)= rate of energy expenditure measured under standardized conditions ▯ Thermogenesis= increased heat production due to an excess caloric intake Core temperature maintained at about 37 degrees Celsius ▯ Physical activity and exercise constitutes for the most variable part of energy expenditure ▯ Humans increase appetite over a broad range of energy expenditure to maintain body weight Sedentary individuals show a net loss of appetite when they undertake an exercise program Moderate-intensity physical activity is an appropriate choice for most Americans to achieve health-related and weight-loss goals Vigorous-intensity physical activity is effective in expending calories and achieving health-related fitness, performance, and weight-loss goals
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