Ch. 12 - Bioenergetics And Regulation Of Metabolism Flashcards
The human body at large is considered an open system. When looking at the cellular level, what sort of system is described?
Closed - only exchanges heat with surroundings.
How much energy does ATP provide?
30 kJ/mol
ATP is a mid level energy carrier. Why is that better than a high level energy carrier if ATP is the main currency of energy in the body?
If it were able to provide more energy, then more energy would be wasted. For example - if a reaction only requires 15kJ/mol and ATP is used then only 15 kJ/mol is wasted. If ATP were higher in energy, then more than 15kJ/mol would be wasted.
Homeostasis
Physiological tendency toward a relatively stable state that is maintained and adjusted
Postprandial state
Well fed state, occurs shortly after eating, lasts 3-5 hours after meal.
Insulin Effect in Postprandial state
1) what are the 3 major target tissues?
2) what does insulin promote in these tissues?
1) liver, muscle, adipose tissue
2) liver: glycogen synthesis (after glycogen stores are filled, liver converts excess glucose to fatty acids and TAGs)
Muscle: glycogen and protein synthesis
Adipose tissue: TAG synthesis
What 5 hormones oppose the action of insulin?
Cortisol Epinephrine Norepinephrine Glucagon Growth hormone
What is the time frame that thyroxine acts over to increase metabolic rate?
Increase occurs after latency of several hours but may last several days.
What is the time frame over which T3 acts?
Produces rapid increases in metabolic rate but has short duration.
What is the respiratory quotient?
CO2 produced / O2 consumed
Differs depending on fuel being utilized
Ghrelin
Secreted by the stomach in response to signals of an impending meal, signals hunger and increases appetite. Stimulates secretion of orexin
Orexin
Further increases appetite, involved in alertness and sleep/wake cycle. Release triggered by ghrelin and hypoglycemia
Leptin
Hormone secreted by fat cells that decrease appetite by suppressing orexin production
