Gross Anatomy of The Heart Quiz

Heart Location and Structure

• The heart is located in the mediastinum, a region in the chest between the lungs.
• The base of the heart points towards the right shoulder, while the apex points towards the left hip.
• The heart's mass is approximately 250-350 grams in adults.
• The epicardium, also known as the visceral pericardium, is the outermost layer of the heart wall.
• The heart is enclosed within a double-walled sac called the pericardium, located within the thoracic cavity.

Cardiac Muscle Tissue

• The myocardium, the middle layer of the heart wall, mainly comprises cardiac muscle tissue.
• Intercalated discs, specialized junctions between cardiac muscle cells, allow ions to flow freely, enabling synchronized contractions.
• Gap junctions within intercalated discs facilitate the rapid spread of electrical impulses throughout the heart.

Heart Chambers and Valves

• The atria (right and left) are the receiving chambers of the heart, collecting blood returning from the body.
• The ventricles (right and left) are the pumping chambers, propelling blood to the lungs and the rest of the body.
• The left ventricle has thicker walls than the right ventricle to pump blood with greater force against higher resistance.
• The pulmonary trunk splits into the right and left pulmonary arteries, carrying deoxygenated blood to the lungs.
• The superior and inferior vena cava return deoxygenated blood to the right atrium from regions above and below the diaphragm, respectively.
• Semilunar valves prevent backflow of blood from the ventricles into the great arteries during ventricular relaxation.
• AV valves (tricuspid and bicuspid) open when ventricular pressure is lower than atrial pressure.
• When the ventricles contract, the AV valves close to prevent backflow of blood into the atria.
• Chordae tendineae anchor the AV valve flaps to papillary muscles, preventing them from everting into the atria.
• The semilunar valves close when ventricular pressure drops below arterial pressure during relaxation.
• The semilunar valves open when ventricular pressure exceeds arterial pressure.

Muscle Structure and Function

• Intercalated discs in cardiac muscle tissue facilitate communication and synchronous contractions, ensuring coordinated heartbeat.
• The troponin-tropomyosin complex is present on the thin filaments of cardiac muscle cells, regulating muscle contraction.
• Transverse tubules (T-tubules) in cardiac muscle cells help transmit action potentials, ensuring uniform contraction of the muscle fibers.
• Desmosomes, specialized junctions, hold cardiac muscle fibers together at their ends, providing structural integrity.
• Z discs, anchoring points for the thin filaments, are located at the ends of sarcomeres in cardiac muscle fibers.

Cardiac Cycle

• During ventricular filling, blood passively flows from the atria into the ventricles, followed by forceful atrial contraction to complete the filling
• End-diastolic volume (EDV) is the volume of blood in the ventricles at the end of atrial contraction.
• Ventricular systole is the period of ventricular contraction, marked by increased pressure within the ventricles.
• Isovolumetric contraction occurs at the beginning of ventricular systole when both AV and semilunar valves are closed, allowing for a brief increase in ventricular pressure without changing volume.
• Atrial contraction adds about 20% to the blood volume in the ventricles.
• Increased ventricular pressure leads to the closing of the AV valves.

Test your knowledge on the gross anatomy of the heart, including details on shape, size, mass, and location within the human body. Explore the key characteristics of the heart's position in relation to other organs.