Homeostasis

• Homeostasis


  Homeo = similar, Stasis = state
• Homeostasis


  • Mammals maintain a relatively constant internal environment
  • Maintaining homeostasis involves conforming, avoiding or regulating
  • Self-regulation
• Claude Bernard (1813-1878) introduced the concept of the internal environment (le milieu interieur)
• Walter Cannon (1872-1945) coined the term "homeostasis"
• Your body


  • Temperature ~37oC
  • pH ~7.4
  • Blood glucose ~90mg/100ml

  
• Coffee

  • Temperature ~95oC
  • pH ~5
  • Blood glucose increases with caffeine
  • Blood glucose increases with sugar
• Thermoregulation


  • Conform (endotherm vs ectotherm)
  • Avoid
  • Regulate
• Negative feedback is the most common form of homeostatic regulation
• Positive feedback is usually not used in homeostatic regulation as it can lead to disruption and illness or even death
• Hormones are involved in homeostatic regulation
• Organ systems contribute to homeostasis
• Cell homeostasis


  Regulated by the cell membrane