Lesson 15 part 2 Anatomy II Exam 4 Study Guide 1 In the absorptive state cells absorb nutrients to be used for growth maintenance and energy reserves In the post absorptive state the liver acts to stabilize blood glucose concentrations It does so first by the breakdown of glycogen reserves and later by gluconeogenesis Over the remainder of the post absorptive state the combination of lipid and amino acid catabolism provides the necessary ATP but these processes generate large quantities of ketone bodies 2 Ketone bodies are formed when lipid and amino acid catabolism causes an increased concentration of acetyl CoA Ketone bodies are indicative of someone who is fasting Ketonemia is the appearance of ketone bodies in the bloodstream which lowers the plasma pH This lower pH must be controlled by buffers When there are high levels of ketone bodies in the bloodstream during prolonged starvation the blood pH drops dangerously low resulting in ketoacidosis This may cause come cardiac arrhythmias or death 3 Complete proteins are those that provide all essential amino acids in sufficient quantities This is found in beef fish poultry eggs and milk Incomplete proteins are deficient in one or more essential amino acids This is seen in plants which do not have vitamin B12 but tofu does Vegetarians must vary their food choices to include combinations of ingredients that meet all of their amino acid requirements since the vegetarians vegans may or may not eat the foods that are considered complete proteins 4 N compounds are compounds that contain nitrogen atoms They are not stored in the body so they must be obtained by recycling N compounds in the body or from the diet N compounds include a Amino acids the framework of all proteins glycoproteins and lipoproteins b Purines and pyrimidines the nitrogenous bases of RNA and DNA c d Porphyrins a complex ring shaped molecule that binds metal ions This is essential to Creatine the energy storage in muscle creatine phosphate hemoglobin myoglobin and cytochromes 5 Minerals are inorganic ions that are released through the dissociation of electrolytes They are important for 3 reasons a b c Ions such as sodium chloride and potassium determine osmotic concentrations of body fluids Ions play a major role in physiological processes Ions are essential cofactors in many enzymatic reactions Minerals are also important because each component of the ETS requires an iron atom and the final cytochrome of the ETS requires a copper ion Therefore the body contains significant mineral reserves that help to reduce the effects of the variations in one s diet However excess minerals can be dangerous since the storage capacity is limited A vitamin is an essential organic nutrient that functions as a coenzyme in vital enzymatic reactions Vitamins are either fat soluble or water soluble based on their chemical structure and characteristics The body contains significant reserves of fat soluble vitamins so that the normal metabolism can continue for several months without dietary sources of fat soluble vitamins Avitaminosis vitamin deficiency disease is rare in fat soluble vitamins hypervitaminosis is more likely Water soluble vitamins are components of coenzymes that are rapidly exchanged between the fluid in the digestive tract and the circulating blood Water soluble vitamins are not stored in the body like fat soluble vitamins so the excess is excreted in the blood 6 The fat soluble vitamins are absorbed primarily from the digestive tract along with lipids of micelles They normally diffuse into the plasma membranes and lipids diffuse into the liver and adipose tissue The fat soluble vitamins include a Vitamin A a structural component of the visual pigment retinal b Vitamin D some is produced by the skin in the sunlight it is converted to Calcitriol which increases the rate of intestinal calcium and phosphorus absorption c Vitamin E stabilizes intracellular membranes d Vitamin K some is produced by intestinal bacteria helps synthesize several proteins including three clotting factors The intestinal epithelium absorbs all water soluble vitamins except B12 because it is too large It must bind to intrinsic factor before it can be absorbed The lack of B12 hinders red blood cell production and causes pernicious anemia 7 A calorie is the energy required to raise 1g of water by 1 degree C A Calorie kilocalorie is the energy required to raise 1kg of water by 1 degree C Lipids have the most energy per gram at 9 46Cal g Proteins are second with 4 32 cal g and carbohydrates follow that with 4 18 Cal g 8 The metabolic rate is the sum of all anabolic and catabolic processes in the body and changes according to one s activity If the daily energy intake exceeds the energy demands then the body stores excess energy as triglycerides in adipose tissue If the daily caloric expenditure exceeds the dietary supply then the body uses these energy reserves and one loses weight The basal metabolic rate is the minimum resting energy expenditure of an awake alert person and is measured under standardized testing conditions In order to measure BMR respiratory activity must be monitored since energy utilization is proportional to oxygen consumption Hormones also affect the metabolic rate A T4 assay that measure the thyroxine on the blood can measure metabolism since thyroxine controls the overall metabolism Cholecystokinin CCK and adrenocorticotropic hormone ACTH also affect metabolism by effecting appetite Leptin is a hormone that is released by adipose tissues during the absorptive state and binds to the CNS neurons that suppress appetite 9 Thermoregulation is a homeostatic mechanism that keeps body temperature within a limited range This is important because enzymes operate in a limited temperature range The body produces heat as a by product of metabolism and an increased physical or metabolic activity generates more heat which is retained by water in the body For body temperature to remain constant heat must be lost to the environment To maintain homeostasis is there is too much heat the body sweats and if there is too little heat the body shivers 10 There are daily oscillations to body temperature Body temperature falls at night and peaks during the day or early evening but the timing varies by the individual Changes to normal body temperature can also be brought about by the ovulatory cycle Pyrexia is a usually temporary elevated body temperature Fever is a body temperature maintained at greater
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