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Bio Test 2
Chapter 46 Metabolism, Control of Energy
| Term | Definition |
|---|---|
| Metabolism | all the bodily activities and chemical reactions in an organism that maintain life |
| metabolic rate | the rate at which an organism uses energy to power these reactions |
| increase in metabolic rate is an increase in | heat |
| absorptive state | when ingested nutrients enter the blood from the GI tract. Some nutrients used immediately and some are stored |
| post absorptive state | when the GI tract is empty of nutrients and the body's own stores must supply energy |
| nutrients absorbed during absorptive state are | carbs, proteins, lipids, nucleic acids, vitamins, minerals and water |
| carbs are absorbed as | monosaccharides (glucose) |
| lipids are absorbed as | triglycerides |
| proteins are absorbed as | amino acids |
| major consumer of glucose are | skeletal muscles |
| if more glucose is absorbed than is immediately needed it is stored | into glycogen in the liver and into fatty acids |
| triglycerides are digested into | fatty acids and monoglycerides diffused across epithelial cells and reassembled |
| triglycerides are used by all organs except the | brain |
| amino acids are taken up by | all body cells and synthesized into proteins |
| in the post absorptive state macromolecules are broken down to supply | monomers that can be used for energy |
| glycogenolysis | glycogen broken down into glucose to raise blood glucose level back to normal |
| gluconeogenesis | enzymes in the liver convert noncarbohydrates into glucose which is then secreted into the blood |
| when animal fails to find food | protein broken down to amino acids and converted to glucose |
| glucose sparing | having other organs and tissues reduce their dependence of glucose sparing it for the CNS and most importantly the brain |
| Glucose sparing is done by increasing the use of | fat as an energy supply |
| lypolysis | essential step to glucose sparing. breaks down triglycerides which releases fatty acids and glycerols |
| Endocrine and nervous systems maintain | homeostatic levels of energy providing nutrients in the blood |
| Insulin | released by pancreas. Regulates blood glucose levels. Promotes transport of glucose from extracellular fluid into cells where it's used for metabolism. |
| Concentration of insulin (increases/decreases) during the absorptive state | increases |
| First step of regulating glucose | insulin binds to a cell-surface receptor |
| Second step of regulating glucose | intracellular signaling pathway is stimulated |
| Third step of regulating glucose | pathway increases availability of transport proteins (GLUTS) in plasma membrane |
| Fourth step of regulating glucose | Vesicles are stimulated which fuses GLUTS with membrane |
| Fifth step of regulating glucose | GLUTS transport glucose into cells |
| Signals from the ______ division of the autonomic nervous system stimulate the secretion of insulin into the blood | parasympathetic |
| Glucagon | protein hormone which is secreted by pancreas and stimulates glycogenolysis and gluconeogenesis |
| norepeinephrine | released from neurons of sympathetic division of autonomic nervous system. Stimulates adipose tissue to release fatty acids into the blood |
| calorie | amount of heat required to raise the temperature of 1 gram of water 1 degree celsius |
| basal metabolic rate | most common measure used to compare the metabolic rates of different species at rest. Metabolic cost of living |
| thermoneutral zone | standard temperature for endotherms. Range where an animal is neither generating heat or losing heat |
| Standard metabolic rate | ectotherms. |
| direct calorimetry | gerbil in ice box |
| indirect calorimetry | CO2 collected |
| Factors that influence metabolic rate | structure, activity, body size |
| structure | skin has lower metabolic rate than brain heart and liver |
| activity | metabolic rate is higher when food is being digested |
| body size | metabolic rate for large animals higher than small ones |
| Mass-specific BMR | amount of energy expended per gram of body mass. |
| Torpor | strategy of lowering internal body temperature to just a few degrees above the environment. |
| Hibernation | torpor that extends for months |
| To keep body weight stable | amount of energy consumed= amount of energy expended |
| satiety | feeling of fullness. Short-term control of feeding. |
| Stomach stretches to fit food, nerves send inhibitory signals from stomach to | appetite center if hypothalamus |
| Long term control of food intake mediated by different | brain molecules, hormones and emotional state |
| Leptin | produced by adipose cells in proportion to fat mass. Increase in stored fat= increase in leptin released, decrease in appetite |
| decrease in adipose mass = | decrease in leptin secretion |
| decrease in leptin secretion= | decrease in BMR |
| decrease in BMR= | increase in appetite |
| effect of high temp on chemical reactions | accelerates chemical reactions |
| effect of high temp on protein function | decreases protein function. Denatures them, changes their shape |
| effect of high temp on membrane structure | membrane more fluid. can become leaky |
| effect of low temp on membrane structure | membrane too rigid |
| homeotherms | maintain their body temp within a narrow range |
| heterotherms | body temp varies with environment |
| radiation | emission of electromagnetic waves by the surfaces of objects |
| evaporation | conversion of water from the liquid state to the gaseous state. Sweat |
| convection | transfer of heat by the movement of air or fluid next to the body. Fan |
| conduction | body surfaces loses or gains heat through direct contact with cooler or warmer substances. Jumping in a pool to cool off |
| On hot days, skin surface blood vessels ______ to dissipate heat | dilate |
| On cold days, skin surface blood vessels _____ to trap heat | constrict |
| countercurrent exchange | heat is transferred between fluids flowing in opposite directions. Between warm arteries and cold veins |
| Evaporative heat loss | changing the rate of water evaporation through perspiration |
| Behavioral adpatations | alter heat loss by radiation, conduction and evaporation. Changing surface area available to sun |
| Acclimization | long-term exposure to a challenging environment results in a fine-tuning of the adaptive mechanisms that persist for as long as the animal lives in that environment. |
| Excess body fat increases the risk of | high blood pressure, cancer, heart disease and diabetes |
| Body mass index (BMI) | preferred method for assessing body fat and health risks |
| Anorexia nervosa | characterized by weight loss. Pathologically obsessed with weight and body image to the point of starvation |
| Bulimia nervosa | recurrent episodes of binge eating followed by use of methods to prevent weight gain: self induced vomiting, laxatives and diuretics |
Created by:
Gianna B
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