Homeostasis

• How Is Breathing Controlled

  • by the muscles, diaphragm and intercostal muscles causing air to move in and out of the lungs
• As oxygen is consumed by the cells, its concentration in the blood begins to fall
• How Do Humans Achieve Voluntary Breathing

  • comes through connections from the cerebral cortex to descending tracts in the spinal cord
  • thus bypassing the respiratory centre in the medulla oblongata enabling us to prevent irritating gasses and water from entering the lungs
• Hyperventilation 


  rapid, deep breathing that provides more oxygen than required and remove more carbon dioxide than necessary
• Thermoregulation


  the regulation of body temperature
• Why Is Thermoregulation Important

  the chemical reactions occurring in cells are very heat sensitive
• Body Temperature Tolerance Limits

  • optimal temperature of 37
  • increased body temperature can cause nerve malfunction, change in structure of proteins and death
• Conduction


  transfer of heat from one object to another with direct contact
• Convection


  transfer of heat via moving air currents
• Radiation


  transfer of heat from one object to another without direct contact
• Evaporation


  transfer of heat as a liquid changes to gas and takes heat with it
• Factors That Influence Body Temperature

  • cellular respiration
  • physical activities
• Metabolic Rate

  the rate at which energy is released by the breakdown of food
• Factors That Affect Metabolic Heat

  • exercise
  • stress
  • body temperature
• Peripheral thermoreceptors are found in the skin and in some mucous membrane
• Peripheral Thermoreceptors


  detect temperature changes in the external environment and sends this information to the hypothalamus
• Central thermoreceptors are found in the hypothalamus