7.3.3 Control of Heart Rate

• The heart consists of four chambers: two atria and two ventricles
• What is the function of the tricuspid valve?

  Controls blood flow
• Match the major blood vessels with their functions:

  Superior vena cava ↔️ Returns blood from the body to the right atrium

  Aorta ↔️ Carries oxygenated blood to the body

  Pulmonary artery ↔️ Transports blood to the lungs

  Pulmonary vein ↔️ Returns blood from the lungs to the left atrium
• The sinoatrial (SA) node and atrioventricular (AV) node control heart rate and cardiac output.
• Cardiac output is calculated using the formula CO = SV × HR
• Order the components of the heart based on their function in blood flow:

  1️⃣ Atria receive blood

  2️⃣ Ventricles pump blood

  3️⃣ Tricuspid valve controls blood flow from the right atrium

  4️⃣ Bicuspid valve controls blood flow from the left atrium

  5️⃣ Pulmonary valve controls blood flow from the right ventricle

  6️⃣ Aortic valve controls blood flow from the left ventricle
• The parasympathetic nervous system decreases heart rate by releasing acetylcholine
• What effect does the sympathetic nervous system have on heart rate?

  Increases heart rate
• The vagus nerve releases acetylcholine to inhibit the SA node, decreasing heart rate.
• Match the nervous system with its effect on heart rate and key hormone:

  Sympathetic ↔️ Increases heart rate, Norepinephrine

  Parasympathetic ↔️ Decreases heart rate, Acetylcholine
• The SA node functions as the heart's natural pacemaker
• Which hormone increases heart rate during stress or physical activity?

  Epinephrine
• The vagus nerve releases acetylcholine
• What hormone is released by the sympathetic nervous system to increase heart rate?

  Norepinephrine
• The parasympathetic nervous system decreases heart rate by releasing acetylcholine
• What is the primary function of the sinoatrial (SA) node?

  Heart's natural pacemaker
• Cardiac output is calculated as stroke volume multiplied by heart rate.
• Epinephrine increases heart rate by stimulating beta-adrenergic receptors
• Which hormone increases basal metabolic rate and heart rate by enhancing sensitivity to catecholamines?

  Thyroxine
• Order the steps of hormonal control of heart rate:

  1️⃣ Hormone released (e.g., epinephrine)

  2️⃣ Hormone binds to receptors

  3️⃣ SA node activity changes

  4️⃣ Heart rate is affected
• Hormonal control of heart rate is faster than neural control.

  False
• What are the four chambers of the heart?

  Two atria, two ventricles
• The tricuspid valve is located between the right atrium and right ventricle
• Which valve controls blood flow from the right ventricle to the pulmonary artery?

  Pulmonary valve
• Match the heart component with its function:

  Atria ↔️ Receive blood from body and lungs

  Ventricles ↔️ Pump blood to lungs and body

  Tricuspid Valve ↔️ Controls blood flow from right atrium to right ventricle

  Bicuspid Valve ↔️ Controls blood flow from left atrium to left ventricle
• Which part of the brain controls heart rate through the autonomic nervous system?

  Medulla oblongata
• The parasympathetic nervous system slows heart rate by releasing acetylcholine
• The relationship between stroke volume, heart rate, and cardiac output is expressed by the formula CO = SV × HR.
• What mechanism does epinephrine use to increase heart rate?

  Stimulates beta-adrenergic receptors
• Stress increases heart rate due to the release of epinephrine