Cardiac Anatomy and Function Quiz

Cardiac Anatomy, Histology, and Function

• Learning Objectives: Understand the mammalian heart structure, location, and relationships; describe the pericardium, myocardium, and endocardium; understand the heart "skeleton"; identify external heart features and cardiac chambers; recognize great vessels and their blood flow; describe heart valves and coronary circulation; and describe heart innervation.

Basic Heart Structure

• Description: The heart is a four-chambered pump (two pumps in series, left and right sides). Each side has an atrium and ventricle, separated by valves.
• Right Side: Receives deoxygenated blood from systemic circulation and pumps it to the lungs.
• Left Side: Receives oxygenated blood from pulmonary circulation and pumps it into systemic circulation.
• Muscle Mass: The left ventricle's muscle mass is greater than the right's, even though they pump equal volumes.
• Shape and Location: Heart shape varies between species (more ovoid in carnivores, conical in horses/ruminants). Located in the thorax, roughly midline (but towards the left).
• Relationships: Located within the mediastinum. The thymus is cranial, lungs and phrenic nerves are lateral, and the trachea/bronchial bifurcation and esophagus are dorsal

Heart Shape and Size

• Shape: Heart shape varies with species, from more ovoid in carnivores to more conical in horses and ruminants.
• Location: In the thorax, approximately midline, though positioned slightly leftwards with the apex contacting the left thoracic wall.
• Relationships: The heart is located within the mediastinum, where it is related to other thoracic structures such as the thymus (cranial), lungs and phrenic nerves (lateral), trachea/bronchial bifurcation and the esophagus (dorsal).
• Size: Generally, the heart is roughly 1% of the bodyweight and is about 2/3 the width/height of the thoracic cavity in carnivores.

Pericardium

• Description: A double-layered sac surrounding the heart. This is referred to as "Serous" and "Fibrous."
• Function: Encloses the heart, forming a fluid-filled space that reduces friction during heartbeats.

Myocardium

• Description: The heart muscle itself, largely composed of cardiomyocytes (contractile cells), specialized pacemaker and conducting cells, interstitial connective tissue, and blood vessels/nerves.
• Arrangement: The muscle fibers arranged interconnecting layers, having a spiral/figure 8 orientation.

Endocardium

• Description: A single layer of flattened endothelial cells with a basement membrane. Forms the innermost layer of the heart and a continuous layer with the blood vessels
• Function: Smooth surface to facilitate blood flow.

Heart Valves

• Atrioventricular (AV) Valves: (Right - Tricuspid; Left - Bicuspid or Mitral) Connect the atria and ventricles.
• Semilunar Valves: (Pulmonary and Aortic) Prevent backflow from the ventricles into the atria.

Blood Vessels and Coronary Circulation

• Coronary Circulation: The arteries supply the heart itself with oxygenated blood; veins drain blood away. The left and right coronary arteries branch from the aorta. Coronary veins return blood to the right atrium through the coronary sinus.

Innervation

• Sympathetic: Largely from major sympathetic ganglia.
• Parasympathetic: Primarily from the vagus nerve (also some recurrent laryngeal branch).

External Features of the Heart

• Atria: The base of the heart, with appendages (auricles).
• Ventricles: The major lower chambers of the heart, with the left ventricle forming the apex.
• Grooves: Grooves separate the atria and ventricles.

Other Features

• Important Clinical Conditions: Fluid accumulation within the pericardial space (such as cardiac tamponade) can have serious effects.
• Skeleton of the heart: A platform of fibrous tissue, critical for proper conduction of electrical impulses.
• Terminal crest: Location of the sinoatrial node, important for initiating the heartbeat.
• Fossa ovalis: a remnant of foetal circulatory structures that closes after birth.

Test your knowledge on the anatomy, histology, and function of the mammalian heart. This quiz covers the heart's structure, the function of its chambers, valves, and the overall circulation process. Perfect for students studying cardiac biology or anatomy!