Human Anatomy: Heart and Muscle Structure

Heart Location and Structure

• The heart is located in the left mediastinum.
• The heart is surrounded by the pericardium.

Heart Chambers

• The heart has four chambers.

Heart Node

• The sinoatrial (SA) node initiates the heart's action potential.

Heart Rate

• The intrinsic rhythm of the SA node is up to 100 beats per minute.

ECG Waves

• The P wave represents atrial depolarization.
• The phase corresponding to ventricular repolarization in an ECG is the T wave.

Muscle Type

• Skeletal muscle is striated and voluntary.

Functional Unit of Skeletal Muscle

• The functional unit of skeletal muscle is the sarcomere.

Muscle Contraction

• Tropomyosin is a muscle protein that binds to calcium ions to initiate contraction.
• Calcium ions are released from the sarcoplasmic reticulum to trigger muscle contraction.

Cardiac Cycle

• The heart sound S2 is caused by the closure of the semilunar valves.
• The first heart sound, S1, is caused by the closure of the atrioventricular (AV) valves.
• Ventricular filling occurs during atrial contraction and before ventricular systole

ECG Intervals

• The QT interval on an ECG represents ventricular depolarization and repolarization.
• The PR interval represents the delay at the AV node.

Other Cardiac Anatomy and Physiology

• Normal adult heart rate range is 60-100 beats per minute.
• The pericardium is the outermost layer surrounding the heart.
• The functional unit of the kidney is the nephron.
• The SA node is the primary pacemaker of the heart.
• Specific cells, like SA and AV node cells, are responsible for conducting electrical impulses.
• The typical position to auscultate the mitral area is the left 5th intercostal space mid-clavicular line.
• A stethoscope is used to auscultate heart sounds to identify any abnormalities.
• A murmur is an abnormal heart sound.
• "Stenosis" means valve narrowing.
• An abnormal heart sound is called a murmur.
• The left lateral position is good for auscultating mitral sounds.
• A high-pitched late-diastolic murmur indicates mitral stenosis.
• S3 is a heart sound during ventricular diastole.
• S1 coincides with ventricular contraction.