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Exam 3

Chapter 19

calorie: the amount of energy needed to increase the temperature of 1 gram of water by 1 degree Celsius.

Kilocalorie: the amount of energy needed to increase the temperature of 1kg of water by 1 degree Celsius.

Two way to obtain energy

1. directly from ATP
2. Indirectly from cellular respiration of glucose, fatty acids, ketone bodies, amino acids and other organic molecules-------these molecules are from food, but they can also be obtained from the glycogen, fat, and protein stored in the body.

Metabolic rate: the total rate of body metabolism.

How to measure the metabolic rate?

1. the amount of heat generated by the body
2. the amount of oxygen consumed by the body per minute.

What influence the metabolic rate?

1. body composistion. the ratio of lean to fat tissue in the body is the biggest factor in determing metabolic rate. ----"percent body fat." the lower your percent body fat, the higher your ratio of lean to fat tissue, and the higher the metabolic rate.
2. Activity level: exercise temporaryily boosts metabolic rate. The longer and harder you exercise, the greater the temporary boost.
3. Diet: eating temporarily raise metabolism By eating small portions of healthy food throughout the day can keep raising metabolism and burn more calories than sticking to the three meals.
4. Age: the older the slower the metabolic rate sue to the loss of muscle mass and the change in fat to lean ratio.
5. Thyroid hormone: helps regulate metabolic rate. hypothroid has reduced metabolic rate. and hyperthroid has increased metabolic rate.
6. Genetics: genetic predispostion affect metabolic rate.

Why body temperature can determine metabolic rate?

1. temperature itself influences the rate of chemical reactions
2. the hypothalamus contains temperature control center, and temperature-sensive cells that act as sensors for changes in the body temperature. In response to the deviation from the set point for body temperature, the control areas of the hypothalamus can direct physiological response that help to correct the deviation and maintain a constant body temperature--thus influence the total metabolic rate.

Basal metabolic rate (BMR) ---- the metabolic rate of an awake, relaxed person 12 to 14 hours after eating and at a comfortable temperature.

• the release of energy in this state is sufficient only for the functioning of the vital organs, such as the brain, skin, muscles, liver, sex organs.
• BMR decreases with age and with the loss of lean body mass. increased with increased cardiovascular exercise and muscle mass.
• An accurate BMR measurement requires that the person's sympathetic nervous system is not stimulated.
• BMR is measure by gass analysis through direct or indirect calorimetry.

Fators that affect BMR

1. Primarily by age, sex and body surface area.
2. Strongly influenced by the level of thyroid secretion. person with hyperthroidism has abnormal high BMR, hypothroidism has low BMR
3. also affected by genetic inheritance, obesity have low BMR.

What is weight loss and weight gain?

• Weight is lost when the caloric value of the food ingested is less than the amount required in cell respiration over a period of time. it can be achieved by dieting clone or in combination with an excerise to raise the metabolic rate.
• Weight is gained when the caloris intake is greater than the energy expenditures, excess calories are stored primarily as fat. Carbodyhrates, protein, or fat can all be converted to fat by the metabolic pathways.
• When the subject were mainted at 10% less than their usual weight, their metabolic rate decreased, and when they were mained at 10% greater than their usual body weight, the metabolic rate increased.

What is anabolism and catabolism?

1. anabolism is the metabolic pathway that create building blocks and compounds from simple presursors. Eg. glycogenesis, glucogeogenesis, peotein synthesis. C cycle, carbon fixation.
2. Catabolism: is the metabolic process that breaks down molecules into smaller units.

Turnover rate: of a molecule is the rate at which it is broken down and resynthesized.

• average daily turnover for carbohydrate is 250 g/day but the average daily dietary requirement for carbohydrate is less than150 gram / day. The average turn over rate for protein is 150 g/ day, 35d/day of protein needed in the diet.
• the minimal amounts of dietary protein and fat required to meet the turnover rte are adequate only if they supply sufficient amounts of the essential amino acids and fatty acids.

Essential amino acids and essential fatty acids

1. 9 essential amino acids are: lysine, tryptophan, phenylalanine, threonine, valine, methionine, leucine, isoleucine, histidine.
2. 2 essential fatty acids: linoleic acid, linolenic acid.

posted by C-T @ 5:34 PM