Kk

• Homeostasis


  Maintaining a relatively constant state of the body's internal environment
• Negative feedback


  The pattern of response to restore the body to normal stable level
• Pulse rate is constantly checked by receptors (sensors) throughout your body
• A stimulus such as elevated pulse rate leads to a reaction by an organ making the response
• An appropriate response will return the pulse rate to normal
• Maintaining homeostasis when exercising


  1. Respiration increases

  2. Breathing and heart rate increase

  3. Remove extra carbon dioxide

  4. Increase oxygen

  5. Body normalizes itself
• Purpose


  To observe an example of homeostasis working to control your body's pulse rate (heart rate)
• The normal average pulse rate is 72 pulse per minute
• Procedure to measure pulse rate


  1. Determine who will exercise and who will measure

  2. Measure resting pulse rate 3 times

  3. Calculate average resting pulse rate

  4. Exercise vigorously for 3 minutes

  5. Measure pulse rate immediately after exercise

  6. Rest for 5 minutes, then measure pulse rate again
• Data Table 1: Resting Pulse Rate


  • Resting Pulse Rate 1
  • Resting Pulse Rate 2
  • Resting Pulse Rate 3
  • Average Resting Pulse Rate
• Data Table 2: Pulse Rate after Exercise


  • After 3 minutes vigorous activity
  • After 5 minutes of rest
  • After 15 minutes of rest
• Blood clotting


  When a wound causes bleeding, the body responds with a positive feedback loop to clot the blood and stop blood loss
• Clotting time


  The time taken by a blood sample to coagulate in vitro under standard conditions
• The normal range of clotting time is 2-8 minutes
• Any change in standard clotting time reflects change in the blood composition and occurrence of bleeding disorders and other diseases
• Procedure to measure clotting time

  1. Apply alcohol to fingertip

  2. Prick finger and collect blood in capillary tube

  3. Start stopwatch

  4. Break capillary tube every 30 seconds

  5. Record time until clot appears
• The expected range of clotting time is 5-10 minutes at 37°C and can be longer at room temperature