Cardiovascular Physiology MBBS basic science MCQ , CEE ,Nepal
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MBBS Basic Science: Cardiovascular System Overview
Structure of the Cardiovascular System
The cardiovascular system consists of the heart, blood vessels, and blood. The heart is a muscular organ located in the thoracic cavity, functioning as a pump to circulate blood throughout the body. It is divided into four chambers: two atria and two ventricles. The right side of the heart pumps deoxygenated blood to the lungs via the pulmonary circulation, while the left side pumps oxygenated blood to the rest of the body through systemic circulation.
Circulation of Blood
Blood circulates through two primary pathways: pulmonary and systemic circulation. Pulmonary circulation carries deoxygenated blood from the right ventricle to the lungs, where gas exchange occurs, and oxygenated blood returns to the left atrium. Systemic circulation moves oxygen-rich blood from the left ventricle to the entire body, supplying tissues with oxygen and nutrients, and returns deoxygenated blood to the right atrium.
Heart Function and Electrical Conduction
The heart functions as a pump through a cycle of contraction (systole) and relaxation (diastole). Electrical impulses generated by the sinoatrial (SA) node initiate heart contractions, spreading through the atria to the atrioventricular (AV) node, and then down the bundle of His and Purkinje fibers, triggering ventricular contraction. This electrical system ensures the coordinated contraction of the heart, maintaining efficient blood flow.
Blood Vessels and Blood Pressure
Blood vessels form a network of arteries, veins, and capillaries that transport blood throughout the body. Arteries carry oxygenated blood away from the heart, while veins return deoxygenated blood back to the heart. Capillaries, the smallest blood vessels, facilitate nutrient and gas exchange between blood and tissues. Blood pressure, the force exerted by circulating blood on the walls of blood vessels, is regulated by cardiac output, blood volume, and resistance within the vessels.
Regulation of the Cardiovascular System
The cardiovascular system is regulated by multiple mechanisms to maintain homeostasis. The autonomic nervous system controls heart rate and vessel diameter, while hormones like adrenaline and angiotensin influence blood pressure and cardiac function. Baroreceptors in major arteries detect changes in blood pressure and trigger reflex responses to stabilize circulation.
Clinical Significance
A comprehensive understanding of the cardiovascular system is essential for diagnosing and managing conditions like hypertension, coronary artery disease, heart failure, and arrhythmias. The MBBS curriculum emphasizes the application of cardiovascular physiology in clinical settings to ensure future physicians can address a range of heart and vascular disorders.
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