11.1.5 Factors Affecting Heart Rate

• What is the purpose of an electrocardiogram (ECG) machine?

  To measure the spread of electricity across the heart
• What do changes in electrical waves on an ECG indicate?

  They can indicate heart problems
• What heart problems can be diagnosed using an ECG?

  Damaged muscles or blockages
• Do you need to remember the P, QRS, and T waves on the ECG for the exam?

  No, you do not need to remember them
• Where can we measure the pulse rate?

  At the carotid pulse in the neck or the radial pulse in the wrist
• What does the pulse rate indicate?

  It indicates where the artery expands as the heart contracts
• What does a stethoscope help to measure?

  It helps to listen to the 'lub dub' sounds of the heart
• What is the relationship between exercise and heart rate?

  • Before exercise, heart rate stays constant
  • Heart rate increases as you begin exercise
  • After exercise, heart rate decreases until it returns to resting rate

  
• Why does heart rate increase during exercise?

  Because muscles contract and need energy from respiration
• What do cells need for respiration during exercise?

  Oxygen and glucose
• What needs to be removed from the body during exercise?

  Carbon dioxide (CO2)
• How does increased heart rate benefit respiring tissues?

  It leads to more blood flowing to them, providing oxygen and glucose
• What happens to CO2 concentration in the blood during exercise?

  It increases
• How does increased CO2 concentration affect blood acidity?

  It increases the acidity of the blood (lowers pH)
• How does the brain respond to increased acidity in the blood during exercise?

  It sends impulses to the heart to contract more frequently and with more force
• Why do fit people have lower resting heart rates?

  Because their hearts become stronger and can contract more forcefully
• What should you avoid using when describing heart function?

  Do not use the word 'pump'
• What is the purpose of an electrocardiogram (ECG) machine?

  To measure the spread of electricity across the heart
• What do changes in electrical waves on an ECG indicate?

  They can indicate heart problems
• What types of heart problems can be diagnosed using an ECG?

  Damaged muscles or blockages
• Do you need to remember the P, QRS, and T waves on the ECG for the exam?

  No, you do not need to remember them
• Where can we measure the pulse rate?

  At the carotid pulse in the neck or the radial pulse in the wrist
• What does the pulse rate indicate?

  It indicates where the artery expands as the heart contracts
• What does a stethoscope help to measure?

  It helps to listen to the 'lub dub' sounds of the heart
• Describe the relationship between exercise and heart rate.

  • Before exercise, heart rate stays constant.
  • Heart rate increases as you begin exercise.
  • After exercise, heart rate decreases until it returns to resting levels.

  
• Why does heart rate increase during exercise?

  Because muscles contract and need energy from respiration
• What do cells need for respiration during exercise?

  Oxygen and glucose
• What happens to CO2 levels during exercise?

  CO2 concentration in the blood increases
• How does increased CO2 concentration affect blood acidity?

  It increases the acidity of the blood and lowers pH
• How does the brain respond to increased acidity in the blood?

  It sends impulses to the heart to contract more frequently and with more force
• Why do fit people have lower resting heart rates?

  Because their hearts become stronger and can contract more forcefully
• What should you avoid using when describing heart function?

  The word 'pump'