Heart

Here are 75 average and 25 difficult questions about the cardiovascular system (specifically the heart, pericardium, position and size of the heart, shape and surface topography of the heart, compartments of the heart, and blood supply), drawing on the provided sources:

Average Difficulty Questions (with answers):

Question: What is another term for the pericardium? Answer: Heart sac.
Question: What type of covering does the pericardium have? Answer: Fibroserous covering.
Question: What fluid is found within the pericardial cavity? Answer: Serous fluid.
Question: What is the function of the serous fluid in the pericardial cavity? Answer: To facilitate easy movement of the heart wall within the pericardial sac.
Question: Name the two main layers of the serous pericardium. Answer: Visceral layer and parietal layer.
Question: What is another name for the visceral layer of the serous pericardium? Answer: Epicardium.
Question: Where is the visceral layer of the serous pericardium firmly attached? Answer: To the heart wall.
Question: What is the pericardial cavity? Answer: The tiny space between the visceral and parietal layers of the serous pericardium, filled with serous fluid.
Question: What can the heart accommodate a small degree of due to the pericardium? Answer: Distension (rhythmic pulsation).
Question: Under what conditions might the heart stretch, according to the sources? Answer: Exercise and disease.
Question: What is pericardiocentesis? Answer: A medical procedure to remove an excess of fluid in the pericardial cavity.
Question: Where is the heart located within the thorax? Answer: Within the mediastinum.
Question: Is the heart positioned symmetrically or asymmetrically in the thorax? Answer: Asymmetrically.
Question: Approximately what percentage of the heart lies to the left of the median plane? Answer: About 60%.
Question: Where is the base of the heart located? Answer: Dorsally.
Question: Where is the apex of the heart located? Answer: Ventrally, close to the sternum.
Question: Between which ribs does the projection of the heart on the chest wall generally extend in the dog? Answer: Between the third and sixth ribs (or thereabouts).
Question: What is the general shape of the heart? Answer: Conical.
Question: What is the hilus of the heart considered to be? Answer: The base of the heart, through which great vessels enter and exit.
Question: Name the four compartments (chambers) of the heart. Answer: Right atrium, right ventricle, left atrium, left ventricle.
Question: Which side of the heart receives deoxygenated blood? Answer: The right side (right atrium and right ventricle).
Question: Where does the right ventricle pump blood to? Answer: To the lungs via the pulmonary trunk.
Question: Which side of the heart receives oxygenated blood? Answer: The left side (left atrium and left ventricle).
Question: Where does the left ventricle pump blood to? Answer: To the rest of the body via the aorta.
Question: What separates the atria from the ventricles? Answer: A transverse, incomplete septum, indicated on the surface by the coronary groove.
Question: What is the function of the atria? Answer: To collect blood and ensure enough is present to fill each ventricle quickly.
Question: What is the function of the ventricles? Answer: To pump blood out of the heart.
Question: Which ventricle typically has thicker walls? Answer: The left ventricle.
Question: Why does the left ventricle have thicker walls? Answer: Because it pumps blood to the entire systemic circulation against higher pressure.
Question: What is the blood supply to the heart called? Answer: The coronary circulation.
Question: From where do the coronary arteries originate? Answer: From the aorta.
Question: Specifically, where on the aorta do the coronary arteries arise? Answer: From two of the three sinuses above the semilunar cusps at the root of the aorta (aortic bulb).
Question: Name the two main coronary arteries. Answer: Left coronary artery and right coronary artery.
Question: Which coronary artery is typically larger? Answer: The left coronary artery.
Question: What are the main branches of the left coronary artery? Answer: Interventricular paraconal branch and circumflex branch.
Question: What area of the heart does the interventricular paraconal branch supply? Answer: The walls of the left ventricle and most of the interventricular septum.
Question: Where does the circumflex branch of the left coronary artery run? Answer: In the coronary groove towards the caudal aspect of the heart.
Question: Where does the right coronary artery run? Answer: Between the right auricle and the pulmonary trunk to the coronary groove, around the cranial aspect of the base of the heart.
Question: What is the function of the heart valves? Answer: To ensure a unidirectional flow of blood and prevent reflux.
Question: Where are the atrioventricular valves located? Answer: Between the atria and the ventricles.
Question: Name the left atrioventricular valve. Answer: Bicuspid or mitral valve.
Question: Name the right atrioventricular valve. Answer: Tricuspid valve.
Question: Where are the semilunar valves located? Answer: At the exit of the ventricles into the great arteries.
Question: Name the semilunar valve at the exit of the right ventricle. Answer: Pulmonary valve.
Question: Name the semilunar valve at the exit of the left ventricle. Answer: Aortic valve.
Question: What is the heart's inherent rhythm controlled by? Answer: The sinoatrial node (pacemaker).
Question: Where is the sinoatrial node located? Answer: Below the epicardium of the right atrial wall ventral to the cranial caval opening.
Question: What is the next node in the heart's conducting system after the sinoatrial node? Answer: The atrioventricular node.
Question: Where is the atrioventricular node located? Answer: Within the interatrial septum, cranial to the opening of the coronary sinus.
Question: What structure arises from the atrioventricular node to conduct the impulse to the ventricles? Answer: The atrioventricular bundle.
Question: What are Purkinje fibers? Answer: Modified cardiac muscle fibers that conduct impulses much more rapidly than those of the common sort.
Question: What is the layer of the heart wall primarily composed of cardiac muscle? Answer: Myocardium.
Question: What is the thin, smooth inner lining of the heart chambers? Answer: Endocardium.
Question: What is the term for the contraction phase of the heart? Answer: Systole.
Question: What is the term for the relaxation phase of the heart? Answer: Diastole.
Question: What is stroke volume? Answer: The volume of blood ejected by the ventricle with each contraction.
Question: What is cardiac output? Answer: The product of stroke volume and heart rate.
Question: What helps in the return of blood to the heart during diastole? Answer: Ventilation and contraction of the diaphragm.
Question: Closure of which valves produces the first heart sound (S1)? Answer: Atrioventricular valves.
Question: Closure of which valves produces the second heart sound (S2)? Answer: Semilunar valves.
Question: In which intercostal space is pericardiocentesis most safely performed in the bovine? Answer: The 5th intercostal space of the left side, directly dorsal to the costochondral joints.
Question: What is the sternopericardial ligament? Answer: A ligament that forms at the ventral apex of the pericardial sac and attaches to the sternum.
Question: What is the approximate percentage of body weight that the heart typically constitutes? Answer: About 0.75%.
Question: Is the heart relatively larger in smaller or larger species? Answer: Smaller species.
Question: How does exercise affect the size of the heart? Answer: It becomes larger (hypertrophied).
Question: What is the coronary groove? Answer: A groove on the surface of the heart that separates the atria from the ventricles.
Question: What is the paraconal (left) interventricular groove? Answer: A shallow groove that descends toward the apex on the cranial aspect of the heart, conveying substantial vessels.
Question: What is the subsinuosal (right) interventricular groove? Answer: A shallow groove that descends toward the apex on the caudal aspect of the heart, conveying substantial vessels.
Question: What is the ligamentum arteriosum? Answer: The fibrosed remnant of the ductus arteriosus.
Question: Where does the ligamentum arteriosum attach? Answer: Joins the pulmonary trunk on its right face.
Question: What is the fossa ovalis? Answer: A depression in the interatrial septum, a remnant of the foramen ovale in the fetus.
Question: What are trabeculae carneae? Answer: Myocardial ridges that project mainly from the outer wall of the ventricles, thought to reduce blood turbulence.
Question: What are papillary muscles? Answer: Muscles within the ventricles that are connected to the cusps of the atrioventricular valves via chordae tendineae.
Question: What are chordae tendineae? Answer: Fibrous cords that connect the cusps of the atrioventricular valves to the papillary muscles.
Question: What is the intervenous tubercle? Answer: A ridge within the right atrium between the openings of the cranial and caudal vena cava.

Difficult Questions (with answers):

Question: Describe the reflection of the pericardium around the great vessels. Answer: The visceral and parietal layers of the pericardium continue into each other at a complicated reflection that runs over the atria and the roots of the great vessels.
Question: How does the position of the heart in ruminants differ slightly from the general description, according to one source? Answer: In ruminants, the heart extends between the planes of the 2nd to 5th intercostal spaces and lies mainly under cover of the limbs in an animal standing square.
Question: Explain the clinical challenge posed by the position of the heart in larger animals. Answer: Much of the heart is covered by the forelimb, making clinical examination, especially auscultation and palpation, a challenge.
Question: Describe the sternopericardiac ligament in more detail, including its origin and insertion in the dog. Answer: The parietal layer of the pericardium has a thick external fibrous covering that blends with the adventitia of the great vessels dorsally and forms a ligament at the ventral apex of the sac to attach to the sternum (sternopericardiac ligament).
Question: What is the significance of the cardiac notch of the lungs? Answer: The cardiac notch allows the heart to come into closer contact with the lateral thoracic wall, separated only by the pericardium, the mediastinum, and the pleura, facilitating auscultation.
Question: How does the exit of the aorta compare to the pulmonary trunk in terms of position at the base of the ventricles? Answer: The exit to the aorta takes a more central position within the heart compared to the pulmonary trunk, which opens more dorsally than the atrioventricular ostium and is craniosinistral to the origin of the aorta.
Question: What is the fibrous skeleton of the heart, and what is its significance? Answer: The fibrous skeleton is a framework of dense connective tissue that surrounds the heart valves and provides attachment for the myocardium. It electrically isolates the atria from the ventricles, except at the atrioventricular node, ensuring coordinated contraction.
Question: Describe the arrangement of chordae tendineae and papillary muscles in relation to the cusps of the atrioventricular valves. Answer: Chordae tendineae connect each cusp of the atrioventricular valves to papillary muscles. Typically, each muscle connects to two cusps, and each cusp receives chordae from multiple papillary muscles, preventing eversion of the cusps during ventricular systole.
Question: What are the ossa cordis, and in which species are they particularly prominent? Answer: Ossa cordis are nodules of bone that develop in the fibrous skeleton, particularly near the aortic valve in the bovine heart.
Question: Explain the variation in the termination of the circumflex branch of the left coronary artery across different species mentioned in the sources. Answer: The circumflex branch of the left coronary artery continues in the coronary groove towards the caudal aspect of the heart, where it terminates close to the right interventricular groove in the horse and pig, but continues into the apex of the heart in carnivores and ruminants.
Question: Describe the venous drainage of the heart. Answer: Deoxygenated blood from the heart muscle is collected by cardiac veins, the largest of which is the great cardiac vein. The great cardiac vein opens separately into the right atrium via the coronary sinus. Many small veins (thebesian veins) also open directly into all four chambers of the heart.
Question: How does the coronary blood flow differ during systole and diastole, and why? Answer: Coronary blood flow is greatest during diastole because during systole, the contracting myocardium compresses the coronary arteries, reducing blood flow. During diastole, the relaxation of the ventricular walls allows for unimpeded blood flow into the coronary vessels.
Question: What is the clinical relevance of collateral circulation in the coronary arteries? Answer: Preformed anastomoses between the coronary arteries can enlarge and provide an alternative blood supply to the myocardium if a major coronary artery becomes occluded, potentially preventing or limiting myocardial infarction.
Question: Explain the embryological development of the interventricular septum and its potential for defects. Answer: The interventricular septum initially appears as a falciform crest formed by myocardial thickening at the ventricular apex, extending to divide the common cavity. Complete closure involves fusion with endocardial cushions and the truncus septum. Failure of complete fusion can result in ventricular septal defects.
Question: How does the left atrium receive blood, and what structural feature prevents backflow? Answer: The left atrium receives oxygenated blood from the lungs via the pulmonary veins. Some sources mention a valve at the entrance of the pulmonary veins into the left atrium in birds, capable of preventing reflux.
Question: Describe the structure and function of the trabecula septomarginalis (moderator band) in the right ventricle. Answer: The trabecula septomarginalis is a single muscular band that passes from the interventricular septum to the outer wall of the right ventricle. It provides a short cut for the electrical impulse from the atrioventricular bundle to reach the papillary muscles of the right ventricle, ensuring coordinated contraction.
Question: How does the innervation of the heart by the autonomic nervous system affect its function? Answer: Sympathetic innervation (via cervical cardiac nerves and caudal thoracic nerves) generally increases heart rate and contractility. Parasympathetic innervation (via branches of the vagus nerve) generally decreases heart rate and contractility, primarily acting on the sinoatrial and atrioventricular nodes.
Question: What is the clinical significance of knowing the projection of heart valves on the chest wall for auscultation? Answer: While the anatomical projections of the heart valves are not necessarily the spots where their closure sounds are best heard (puncta maxima), they provide a general guide for placing the stethoscope to auscultate different valves.
Question: Explain why the heart is considered to be located within the mediastinum. Answer: The mediastinum is the partition that separates the right and left pleural cavities. The heart, enclosed within the pericardium, resides within this central thoracic compartment, along with other structures like the trachea, esophagus, and major blood vessels.
Question: How might effusion within the pericardial cavity affect the heart's function? Answer: Excessive fluid accumulation in the pericardial cavity (pericardial effusion) can increase pressure on the heart, limiting its ability to fill properly during diastole. This condition, known as cardiac tamponade, can severely impair cardiac output.
Question: Describe the blood supply to the atrial myocardium compared to the ventricular myocardium. Answer: Both atria and ventricles are supplied by branches of the coronary arteries. The specific distribution and dominance (whether the left or right coronary artery supplies the majority of the ventricles) can vary between species. The sources don't explicitly detail differences in the density or amount of blood supply between atrial and ventricular myocardium, but given the thicker walls and greater workload of the ventricles, they likely have a more extensive capillary network.
Question: What are the implications of the heart's position relative to the diaphragm, particularly in species like cattle? Answer: The caudal surface of the heart faces toward the diaphragm and may be indirectly related through it to cranial abdominal organs. This is of importance in certain species such as cattle, where conditions like traumatic reticuloperitonitis can lead to traumatic pericarditis due to the proximity and potential for direct or indirect spread of inflammation.
Question: Explain the function of the ligament at the ventral apex of the pericardial sac in limiting the displacement of the heart. Answer: The sternopericardial ligament, attaching the pericardium to the sternum, along with the anchorage provided by the great vessels at the base of the heart, helps to stabilize the heart within the thoracic cavity and limits excessive movement or displacement.
Question: How does the size of the heart typically change from a newborn animal to an adult? Answer: The heart grows proportionally with the animal's overall body size. In the newborn calf, the isthmus of the aorta is greatly constricted, but the heart attains usual proportions within a few days of birth.
Question: Discuss the significance of the connective tissue layer of the parietal pericardium. Answer: The parietal pericardium has a thick external fibrous covering, which is a key component of the pericardium. This layer provides structural integrity and protection to the heart and helps to anchor it within the mediastinum. It also blends with the adventitia of the great vessels and forms ligaments that attach to the sternum.