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Bio Test 2

Chapter 46 Metabolism, Control of Energy

TermDefinition
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