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How does cardiac output vary between resting conditions and during intense exercise?
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Cardiac output is approximately 5 liters/min at rest; during exercise, it can increase to 13-15 liters/min for untrained individuals and 30-40 liters/min for elite athletes.
What is the relationship between total blood pumped and elite athletic performance?
Elite athletes have a significantly higher cardiac output during exercise (up to 40 liters/min), enabling greater delivery of oxygen and nutrients, which supports enhanced physical performance.
What long-term adaptations occur in muscle tissues with consistent exercise?
Long-term adaptations include increased microvascularization, leading to an enhanced number of capillaries, which improves oxygen delivery to muscle tissues.
Explain what happens in the aorta when the heart pumps blood.
The aorta, as the largest artery, utilizes elastic recoil and its large size to help distribute oxygenated blood from the heart to various branches reaching the body's tissues.
What factors influence cardiac output during exercise?
Cardiac output during exercise is influenced by heart rate (beats per minute) and stroke volume (volume of blood per beat).
Why does the resting heart rate decrease in trained individuals?
The resting heart rate decreases because the heart becomes more efficient and stronger with training, pumping more blood per beat with less effort.
How does stroke volume change with exercise and why?
Stroke volume increases during exercise due to stronger contractions of the left ventricle, allowing more blood to be pumped per beat.
List the four valves of the heart involved in blood flow direction.
The four heart valves are the tricuspid valve, pulmonary valve, mitral valve, and aortic valve.
What structural adaptation occurs in the heart muscle of elite athletes over time?
In elite athletes, myocardial mass can increase by 50-75% due to the hypertrophy of cardiac muscle cells, improving cardiac efficiency.
What is the primary function of the left ventricle in the heart?
The left ventricle's primary function is to pump oxygenated blood to the entire body through the aorta.
What sequence does blood follow after it returns deoxygenated to the heart?
Deoxygenated blood enters the right atrium, is pumped into the right ventricle, transported to the lungs to become oxygenated, then moves to the left atrium and finally the left ventricle before being pumped out via the aorta.
Describe the role of the Frank-Starling Law in exercise physiology.
The Frank-Starling Law states that the heart contracts more forcefully with an increased volume of blood filling it, which enhances the venous return and boosts cardiac output during exercise.
How does the blood flow change in muscles during exercise compared to rest?
Blood flow to muscles increases from 3-4 ml/min per 100g at rest to up to 200 ml/min during exercise for average individuals and up to 400 ml/min for elite athletes.
How does forceful contraction of vein walls assist in exercise?
Forceful contraction of vein walls aids in increasing venous return to the heart, thereby enhancing overall blood circulation and oxygen delivery during physical activity.
What does vasoconstriction of peripheral arterioles achieve during exercise?
Vasoconstriction of peripheral arterioles redirects blood flow to exercising muscles while reducing flow to non-essential areas, such as the intestines.
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