Homeostasis

• Homeostasis


  The process of keeping a constant internal state despite changes in the environment
• Maintaining body temperature


  1. Heat is gained from respiration and redistributed by the circulatory system

  2. Heat is lost through the skin by radiation, conduction, and evaporation
• Water balance


  The process of maintaining a constant level of water in the body, regulated by the kidneys
• Thermoregulation


  The process of maintaining a constant body temperature, involving sensors, a processing centre, and effectors
• Reactions to being too hot or cold

  Too cold: Shivering, hair standing up, vasoconstriction

  Too hot: Sweating, vasodilation
• How does the body maintain balance?

  1. Water Balance

  2. Kidneys excrete waste products and water to help keep conditions the same
• Thermoregulation


  1. Where are the sensors/receptors?

  2. What is the processing centre?

  3. Effectors

  4. How they help maintain a constant body temperature
• Too cold?


  1. Muscles contract which results in shivering to produce heat

  2. Effector muscles make hair stand up to trap a layer of warm air

  3. Vasoconstriction: vessels constrict to divert blood away from skin to core
• Too hot?


  1. No sweat made

  2. Hair is flat against skin

  3. Vasodilation: vessels dilate to allow heat to move into air

  4. Sweating; energy is lost as water evaporates from skin
• Thermoregulation is an example of negative feedback
• If body has too much water

  1. Hypothalamus detects it

  2. Pituitary produces/releases less ADH

  3. Kidneys reabsorb less water

  4. More dilute urine is made (less concentrated)
• Why is the entire body not at 37 degrees celsius?

  Because extremities have a larger surface area so they lose heat faster. Your extremities also do not contain vital organs.

  • Your core must be kept at or close to 37 degrees C
• Heat is produced during respiration
• Examples of effectors:

  • Sweat gland
  • Hair erector muscle
• What is vasodilation?


  Expansion of blood vessel - more blood can flow through the capillaries in the skin
• What is vasoconstriction?


  Vasoconstriction is the narrowing of blood vessels, resulting in a decrease in blood flow.
• When you’re too hot does vasoconstriction occur or vasodilation?

  Vasodilation - vessels dilate to allow heat to move into the air
• When you’re too cold, does vasoconstriction occur or vasodilation?

  Vasoconstriction - vessels constrict to divert blood away from skin to core
• What is water balance important for?

  It is crucial for maintaining homeostasis, regulating body temperature, and supporting cellular functions.
• What happens if water loss exceeds water intake?

  Dehydration occurs.
• What are some ways the body loses water?

  The body loses water through sweating, urine, and feces.
• Why is water important for cellular functions?

  Water is necessary for metabolism, protein synthesis, and waste removal at the cellular level.
• Where are the kidneys found in the body?

  In the abdominal cavity below the rib cage
• The kidneys are embedded in fatty tissue for protection and to help with blood flow
• If the body has too little water:

  1. Hypothalamus detects low levels of water in the blood
  2. Pituitary gland releases more ADH
  3. Kidneys re-absorb more water into blood
  4. Less volume of urine produced (more concentrated)