Anatomy of the Heart

Anatomy

• The heart is a four-chambered muscular organ located in the mediastinum, between the lungs.
• It is roughly the size of a clenched fist.
• The heart's apex (tip) points towards the left hip.
• The heart wall is composed of three layers: epicardium (outer), myocardium (middle, muscular), and endocardium (inner).

Chambers

• The heart has four chambers: two atria (receiving chambers) and two ventricles (pumping chambers).
• The right atrium receives deoxygenated blood from the body.
• The right ventricle pumps deoxygenated blood to the lungs.
• The left atrium receives oxygenated blood from the lungs.
• The left ventricle pumps oxygenated blood to the body.

Valves

• The heart valves regulate blood flow through the chambers.
• The atrioventricular (AV) valves (tricuspid and mitral) prevent backflow from the ventricles to the atria.
• The semilunar valves (pulmonary and aortic) prevent backflow from the arteries to the ventricles.

Blood Flow

• Deoxygenated blood enters the heart through the superior and inferior vena cava into the right atrium.
• Blood flows from the right atrium to the right ventricle and then to the lungs via the pulmonary arteries.
• In the lungs, blood becomes oxygenated.
• Oxygenated blood returns to the heart through the pulmonary veins to the left atrium.
• Blood flows from the left atrium to the left ventricle and then to the body via the aorta.

Conduction System

• The heart has an intrinsic conduction system that initiates and coordinates its contractions.
• The sinoatrial (SA) node is the pacemaker of the heart, initiating the heartbeat.
• The atrioventricular (AV) node delays the impulse, allowing the atria to contract before the ventricles.
• The bundle of His and Purkinje fibers conduct the impulse throughout the ventricles, causing them to contract.

Cardiac Cycle

• The cardiac cycle is a series of events that occur during one complete heartbeat.
• It consists of systole (contraction) and diastole (relaxation) of the atria and ventricles.
• The cycle repeats rhythmically, maintaining blood flow throughout the body.
• Pressure changes drive blood flow through the heart.

Heart Sounds

• Heart sounds (lub-dub) are produced by the closing of the heart valves.
• The "lub" sound is produced by the closing of the AV valves.
• The "dub" sound is produced by the closing of the semilunar valves.

Cardiac Output

• Cardiac output (CO) is the amount of blood pumped by each ventricle per minute.
• CO is calculated by multiplying stroke volume (SV) by heart rate (HR).
• Factors influencing CO include preload, afterload, and contractility.
• Preload refers to the degree of stretch of the ventricles before they contract.
• Afterload refers to the pressure opposing blood ejection from the ventricles to the arteries.
• Contractility is the force of ventricular contraction.

Coronary Circulation

• The heart receives its own blood supply through the coronary arteries.
• The coronary arteries branch off the aorta and supply the myocardium with oxygen and nutrients.
• Blockages in these arteries (coronary artery disease) can lead to angina, heart attack, and death.

Cardiac Disorders

• Various heart conditions can affect function and structure.
• Examples include: mitral valve prolapse, heart failure, arrhythmias, and congenital heart defects.
• Specific symptoms of heart conditions can vary.

यह क्विज़ दिल की संरचना, कक्षों, वाल्वों और रक्त प्रवाह के बारे में जानकारी प्रदान करता है। आप सीखेंगे कि दिल में चार कक्ष होते हैं और कैसे रक्त प्रवाहित होता है। साथ ही, यह जानते हैं कि वाल्व रक्त प्रवाह को कैसे नियंत्रित करते हैं।