Metabolism P4

• Fasted State/Catabolic


  Breaking down larger molecules
• Fed State/Anabolic


  Storage for later use
• Insulin


  Pancreatic Beta cells
• Glucagon


  Pancreatic Alpha cells
• Fed state: Insulin dominates


  • Glucose oxidation
  • Glycogen synthesis
  • Fat synthesis
  • Protein synthesis
  • Glycogenolysis
  • Gluconeogenesis
  • Ketogenesis
• Plasma glucose concentration


  • Plasma glucagon concentration
  • Plasma insulin concentration
• Metabolism is controlled by the insulin:glucagon ratio
• Nervous and Endocrine systems in control of storage and mobilize as needed
• Excess Glucose is stored as Glucose, Glycogen, Fat
• Glucagon and Insulin work to maintain homeostatic balance
• Anya had been looking forward to her first backpacking trip to the Canadian Rockies
• Anya unpacked her equipment and ran through a mental checklist of the essential gear she had brought
• Anya's hike went well at first
• Anya was starting to feel quite cold and rather fatigued
• Mechanisms of heat loss


  • Conductive heat loss
  • Radiant heat loss
  • Convective heat loss
  • Evaporative heat loss
• Physiologic responses to maintain normal body temperature


  1. Minimize heat loss

  2. Maximize heat production
• Mechanisms and structures responsible for initiating and controlling physiologic responses


  • Neural
  • Endocrine
  • Metabolic
• Humans are homeothermic temperature regulated within a narrow range
• 40% of energy released by catabolism can be captured as ATP, rest is lost as heat
• Cellular Metabolism inside the cell gives off heat
• Thermoregulatory center is in the hypothalamus
• Alterations in cutaneous blood flow conserve or release heat
• Sweat contributes to heat loss
• We are better suited to adapt to HEAT than cold
• Vasoconstriction and vasodilation are neural responses
• Non-shivering thermogenesis and increased metabolic activity are endocrine responses
• Increased cardiovascular and muscular activity are metabolic responses
• Countercurrent heat exchange occurs in the blood vessels
• Vasoconstriction to the dermis and shunting to the deep veins limits heat loss
• Shivering increases skeletal muscle tone to produce heat
• Non-shivering thermogenesis in "brown fat" increases metabolic heat generation
• Frostbite involves freezing of the skin
• Hypothermia involves losing heat faster than it can be produced