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Questions and Answers
What is the average heart rate in adults?
What is the average heart rate in adults?
Which factor is known to decrease heart rate?
Which factor is known to decrease heart rate?
What is the stroke volume in adults?
What is the stroke volume in adults?
How does sympathetic stimulation affect cardiac output?
How does sympathetic stimulation affect cardiac output?
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During which phase of the cardiac cycle does blood pass from the atria to the ventricles?
During which phase of the cardiac cycle does blood pass from the atria to the ventricles?
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What separates the right atrium from the right ventricle?
What separates the right atrium from the right ventricle?
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Which vessels carry oxygenated blood away from the heart?
Which vessels carry oxygenated blood away from the heart?
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What is the function of the heart valves?
What is the function of the heart valves?
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What structures prevent the eversion of the A-V valves during ventricular contraction?
What structures prevent the eversion of the A-V valves during ventricular contraction?
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Which part of the heart starts the systemic circulation?
Which part of the heart starts the systemic circulation?
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Which type of circulation is responsible for sending deoxygenated blood to the lungs?
Which type of circulation is responsible for sending deoxygenated blood to the lungs?
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What is the role of the atria in the heart?
What is the role of the atria in the heart?
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What connects the papillary muscles to the atrioventricular valves?
What connects the papillary muscles to the atrioventricular valves?
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What role does the sino-atrial node play in the heart's function?
What role does the sino-atrial node play in the heart's function?
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What is cardiac output a product of?
What is cardiac output a product of?
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During which stage of the cardiac cycle does blood return to the atria from the body?
During which stage of the cardiac cycle does blood return to the atria from the body?
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How does thyroxin influence cardiac output?
How does thyroxin influence cardiac output?
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What is the primary role of the ventricles in the heart?
What is the primary role of the ventricles in the heart?
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What type of blood is delivered by the aorta?
What type of blood is delivered by the aorta?
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What separates the left atrium from the left ventricle?
What separates the left atrium from the left ventricle?
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What is the function of the pericardium?
What is the function of the pericardium?
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Which structure collects deoxygenated blood returning from the body?
Which structure collects deoxygenated blood returning from the body?
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Which component prevents the backflow of blood into the ventricles during contraction?
Which component prevents the backflow of blood into the ventricles during contraction?
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Which valve allows blood to exit the left ventricle into the aorta?
Which valve allows blood to exit the left ventricle into the aorta?
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What are the two primary divisions of the circulatory system?
What are the two primary divisions of the circulatory system?
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Study Notes
Introduction to Cardiovascular Physiology
- Presented by Dr. Sherif Diaaeldin, Assistant Professor of Physiology at Ain Shams University.
Functional Anatomy of the Heart
- The heart is a hollow muscular organ enclosed by the pericardium, a connective tissue sac.
- The pericardium protects the heart, reducing friction during contractions.
- The heart wall is composed of cardiac muscle.
- The heart is divided into right and left halves, each with one atrium and one ventricle.
Heart Valves
- The right atrium is separated from the right ventricle by the tricuspid valve.
- The left atrium is separated from the left ventricle by the bicuspid (mitral) valve.
- Both valves are called atrioventricular (A-V) valves.
- Within the ventricles are papillary muscles, with chordae tendineae attached. This prevents the valves from inverting during ventricular contraction.
Divisions of the Circulation
- Systemic circulation: Begins in the left ventricle, then flows through the aorta, arteries, arterioles, capillaries, venules, and veins, returning to the superior and inferior venae cavae, and into the right atrium.
- Pulmonary circulation: Begins in the right ventricle, then flows through the pulmonary artery, pulmonary capillaries, pulmonary veins, and into the left atrium.
Functions of the Atria and Ventricles
- Atria are entryways to the ventricles.
- Ventricles pump blood throughout the body (right to lungs, left to body).
- Oxygenated blood leaves the heart via the aorta.
- Deoxygenated blood enters the heart via the vena cavae and exits via the pulmonary artery to the lungs.
- Pulmonary veins carry oxygenated blood back to the heart.
Mechanism of Heart Beating
- Heart rate averages 72 beats per minute in adults.
- The sinoatrial (SA) node, located in the right atrium, initiates the heartbeat.
- The impulse from the SA node spreads through the atria causing them to contract.
- The impulse reaches the atrioventricular (AV) node, then travels through the Bundle of His and Purkinje fibers to the ventricles, causing ventricular contraction.
Factors Affecting Heart Rate
- Increased heart rate: Sympathetic stimulation, exercise, increased body temperature (every degree Celsius increases the heart rate by 10 beats per minute), fever, hormones (thyroxin and adrenalin).
- Decreased heart rate: Parasympathetic stimulation, sleep, decreased body temperature, and certain drugs (e.g., beta-blockers).
Heart Sounds
- S1 ("Lubb"): Sound of mitral and tricuspid valve closure, marking the start of ventricular systole. Heard loudest at the apex of the heart.
- S2 ("Dubb"): Sound of pulmonic and aortic valve closure, marking the end of ventricular systole. Heard loudest at the base of the heart.
The Cardiac Cycle
- The cardiac cycle includes one systole-diastole sequence, lasting approximately 0.8 seconds.
- Atrial systole: Blood moves from atria to ventricles.
- Ventricular systole: Blood is pumped to the lungs (right ventricle) and the rest of the body (left ventricle).
- Atrial diastole: Blood enters atria from veins.
- Ventricular diastole: Blood enters ventricles from atria.
The Cardiac Output
- Cardiac output is the amount of blood pumped by each ventricle per minute (approximately 5.5 liters/minute).
- Stroke volume is the amount of blood pumped by each ventricle per beat (approximately 80 milliliters).
- Cardiac output= heart rate × stroke volume.
Factors Affecting Cardiac Output
- Increased cardiac output: Sympathetic stimulation.
- Decreased cardiac output: Parasympathetic stimulation.
- Catecholamines and thyroxin increase cardiac output.
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Description
Explore the functional anatomy of the heart, including its structure and valves, in this comprehensive quiz. Understand the divisions of circulation and the role of each component in maintaining cardiovascular health.
