Cardiovascular System

The difference in oxygen content between arterial blood and venous blood is known as:

• Oxygen saturation

• Oxygen tension

• Arteriovenous oxygen difference

• Oxygen capacity

Answer explanation

The arteriovenous oxygen difference refers to the difference in oxygen content between arterial and venous blood, indicating how much oxygen is extracted by tissues. This is the correct term for the difference in oxygen levels.

What is the action of muscles contracting to compress veins and push blood back toward the heart called?

• Respiratory pump

• Skeletal muscle pump

• Pocket Valves

• Gravity

Answer explanation

The action of muscles contracting to compress veins and push blood back toward the heart is called the skeletal muscle pump. This mechanism helps facilitate venous return, especially in the limbs.

The process of redistribution of blood during exercise involves:

• increased blood flow to muscles and decreased flow to non-essential organs

• decreased blood flow to muscles and increased flow to non-essential organs

• equal distribution of blood to all body parts

• no change in blood distribution

Answer explanation

During exercise, the body prioritizes blood flow to active muscles to meet their increased oxygen and nutrient demands, while reducing blood flow to non-essential organs, making the correct choice: increased blood flow to muscles and decreased flow to non-essential organs.

What is the volume of blood pumped from the heart in 1 minute called?

• Cardiac output

• Stroke volume

• Heart rate

• Blood pressure

Answer explanation

The volume of blood pumped from the heart in 1 minute is called cardiac output. It is calculated by multiplying stroke volume (the amount of blood pumped per beat) by heart rate (the number of beats per minute).

What is the formula for cardiac output?

• Cardiac output (Q) is calculated using the formula: Q = Stroke Volume (SV) x Heart Rate (HR).

• Cardiac output (Q) is calculated using the formula: Q = Blood Pressure (BP) x Heart Rate (HR).

• Cardiac output (Q) is calculated using the formula: Q = Stroke Volume (SV) / Heart Rate (HR).

• Cardiac output (Q) is calculated using the formula: Q = Blood Pressure (BP) / Stroke Volume (SV).

Answer explanation

The correct formula for cardiac output (Q) is Q = Stroke Volume (SV) x Heart Rate (HR). This means cardiac output is determined by the amount of blood pumped with each heartbeat multiplied by the number of beats per minute.

What is blood pressure?

• The force of blood against the walls of arteries

• The amount of blood in the body

• The rate at which the heart beats

• The temperature of the blood

Answer explanation

Blood pressure is defined as the force of blood against the walls of arteries. This is crucial for understanding how blood circulates throughout the body, unlike the other options which refer to different aspects of blood or heart function.

The role of the sympathetic pathway at the start of exercise is to:

• increase heart rate and blood flow to muscles

• decrease heart rate and blood flow to muscles

• maintain current heart rate and blood flow

• none of the above

Answer explanation

The sympathetic pathway activates during exercise to increase heart rate and enhance blood flow to muscles, ensuring they receive more oxygen and nutrients needed for physical activity.

Explain what happens to arteriovenous oxygen difference (A–VO2 diff) following the onset of exercise.

• A–VO2 diff decreases due to increased oxygen delivery to muscles.

• A–VO2 diff remains unchanged as exercise does not affect it.

• A–VO2 diff increases due to greater oxygen extraction by muscles.

• A–VO2 diff fluctuates randomly without a specific pattern.

Answer explanation

During exercise, muscles require more oxygen, leading to an increase in A–VO2 diff as they extract more oxygen from the blood. This reflects enhanced oxygen utilization by active tissues.

Explain how redistribution of blood is achieved through exercise.

• Through vasodilation and vasoconstriction of blood vessels

• By increasing the heart rate only

• By decreasing the blood pressure

• Through the respiratory system

Answer explanation

Redistribution of blood during exercise is primarily achieved through vasodilation and vasoconstriction of blood vessels. This process directs more blood to active muscles while reducing flow to less active areas, optimizing performance.

What physiological change occurs in the heart during intense exercise?

• Decrease in heart rate

• Increase in stroke volume

• Decrease in stroke volume

• Increase in blood pressure only

Answer explanation

During intense exercise, the heart adapts by increasing stroke volume, which is the amount of blood pumped with each beat. This allows for more efficient oxygen delivery to muscles, enhancing performance.