The Cardiovascular System

• What are the two main circulatory circuits in the body?

  • Pulmonary circulation – Carries deoxygenated blood from the heart to the lungs for gas exchange and returns oxygenated blood to the heart.
  • Systemic circulation – Distributes oxygenated blood from the heart to the body tissues and returns deoxygenated blood back to the heart.
• Describe the flow of blood through the pulmonary circulation Deoxygenated blood from the body enters the right atrium via the superior and inferior vena cava.Blood moves through the tricuspid valve into the right ventricle.The right ventricle contracts, pushing blood through the pulmonary valve into the pulmonary trunk.The pulmonary trunk bifurcates into the right and left pulmonary arteries, which transport blood to the lungs.In the lung capillaries, gas exchange occurs: CO₂ is expelled, and O₂ is absorbed.Oxygenated blood returns to the heart via the pulmonary veins, emptying into the left a...
• Describe the flow of blood through the systemic circulation Oxygenated blood from the left atrium passes through the mitral (bicuspid) valve into the left ventricle.The left ventricle contracts, forcing blood through the aortic valve into the aorta.The aorta distributes blood to the body via arteries (e.g., carotid, subclavian, renal, femoral).Arteries branch into arterioles, which further divide into capillaries, where nutrient and gas exchange occurs in tissues.Deoxygenated blood is collected by venules, which merge into veins.Major veins (e.g., superior and inferior vena cava) return blood ...
• Why does the left ventricle have a thicker wall than the right ventricle? The left ventricle has a thicker myocardium because it pumps blood into the systemic circulation, which requires higher pressure to distribute blood throughout the body.The right ventricle pumps blood only to the lungs, which is a shorter and lower-resistance circuit, requiring less force.
• What is the role of heart valves in blood circulation? Atrioventricular (AV) valves (tricuspid & mitral) prevent backflow into the atria during ventricular contraction.Semilunar valves (pulmonary & aortic) prevent backflow into the ventricles after blood is ejected into the arteries.They ensure unidirectional blood flow, preventing regurgitation and maintaining efficiency.
• What happens if there is a blockage in the pulmonary or systemic circulation? Pulmonary blockage (e.g., pulmonary embolism): Reduced oxygenation of blood, increased right ventricular strain, possible respiratory distress.Systemic blockage (e.g., atherosclerosis): Decreased oxygen supply to tissues, potential ischemia, risk of stroke or heart attack.
• What are the five classes of blood vessels? Arteries – Carry blood away from the heart.Arterioles – Smallest branches of arteries.Capillaries – Smallest blood vessels, allowing exchange between blood and interstitial fluid.Venules – Collect blood from capillaries.Veins – Return blood to the heart
• What is the function of arteries? Arteries carry oxygenated blood away from the heart to the body's tissues (except for pulmonary arteries, which carry deoxygenated blood to the lungs).
• What are arterioles, and what is their primary function? Arterioles are small-diameter arteries that branch from larger arteries.Contain a high proportion of smooth muscle, allowing them to regulate blood pressure and blood flow by vasoconstriction and vasodilation.Act as resistance vessels controlling blood distribution to capillary networks.
• What is the primary function of capillaries? They facilitate gas exchange (O2, CO2), nutrient delivery, and waste removal.Three types: Continuous, Fenestrated, Sinusoidal.
• What are venules, and what is their role in circulation? Venules are small veins that receive deoxygenated blood from capillaries.They have thin walls with minimal smooth muscle.Serve as sites of immune cell migration and fluid exchange with tissues.
• What is the function of veins? Veins return deoxygenated blood to the heart (except for pulmonary veins, which carry oxygenated blood from the lungs to the heart). They have valves to prevent backflow.
• What structural differences exist between arteries and veins? Arteries: Thicker tunica media, more elastic fibers, narrow lumen, no valves.Veins: Thinner tunica media, less elasticity, wider lumen, contain valves to prevent backflow.
• What role do valves play in veins? Valves in veins prevent backflow of blood, ensuring one-way circulation back to the heart, especially in the lower limbs where blood must flow against gravity.
• How does blood pressure differ between arteries, capillaries, and veins? Arteries: High pressure due to direct pumping from the heart.Capillaries: Moderate pressure, allowing for exchange of substances.Veins: Low pressure, requiring valves and skeletal muscle contraction to aid return flow.
• What are the three types of capillaries and their functions? Continuous capillaries – Most common; found in muscles, skin, and CNS; allow selective permeability.Fenestrated capillaries – Have pores; found in kidneys, intestines, and endocrine glands; facilitate increased exchange.Sinusoidal capillaries – Large gaps; found in liver, bone marrow, and spleen; allow passage of large molecules and cells.
• What is the function of the tunica media in different blood vessels? In arteries, the tunica media is thick, with smooth muscle and elastin, allowing for vasoconstriction and vasodilation.In veins, it is thinner and contains less smooth muscle, making veins less resistant to pressure changes.In arterioles, it is highly muscular and controls peripheral resistance and blood pressure regulation.
• What is the function of the tunica intima in different blood vessels? Innermost layer of blood vessels, composed of a single layer of endothelial cells supported by a thin layer of connective tissue.Provides a smooth, frictionless surface to reduce resistance to blood flow.Secretes substances like nitric oxide (NO) to regulate vasodilation and blood clotting.In capillaries, it is the only layer present, allowing for efficient diffusion of gases and nutrients.In arteries, it contains an internal elastic lamina that provides flexibility and recoil.
• What is the function of the tunica externa (adventitia) in different blood vessels? Outermost layer of blood vessels, composed of connective tissue, collagen, and elastic fibers.Provides structural support and protection to prevent vessel overexpansion.Contains vasa vasorum (small blood vessels that supply larger vessel walls).In veins, it is thicker than the tunica media, reinforcing their structure since veins experience lower pressure.In arteries, it helps anchor vessels to surrounding tissues.
• How many chambers does the heart have? The heart has four chambers:Right Atrium – Receives deoxygenated blood from the body via the superior and inferior vena cava.Right Ventricle – Pumps deoxygenated blood to the lungs via the pulmonary artery.Left Atrium – Receives oxygenated blood from the lungs via the pulmonary veins.Left Ventricle – Pumps oxygenated blood to the body via the aorta.
• What is the function of the right atrium? The right atrium receives deoxygenated blood from the body via the superior and inferior vena cava and sends it to the right ventricle.
• What is the function of the right ventricle? The right ventricle pumps deoxygenated blood into the pulmonary artery for oxygenation in the lungs.
• What is the function of the left atrium? The left atrium receives oxygenated blood from the pulmonary veins and transfers it to the left ventricle.
• What is the function of the left ventricle? The left ventricle pumps oxygenated blood into the aorta, which distributes it throughout the body.
• Name the major blood vessels that carry deoxygenated blood to the heart Superior vena cava – Returns deoxygenated blood from the upper body to the right atrium.Inferior vena cava – Returns deoxygenated blood from the lower body to the right atrium.Coronary sinus – Collects blood from the heart's own circulation and drains into the right atrium.
• What is the function of the pulmonary artery? The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs for gas exchange.
• What is unique about the pulmonary veins? The pulmonary veins are unique because they carry oxygenated blood from the lungs to the left atrium, whereas most veins carry deoxygenated blood.
• What are the major branches of the aorta? Ascending aorta – Supplies coronary arteries.Aortic arch – Gives rise to the brachiocephalic artery, left common carotid artery, and left subclavian artery.Descending aorta – Supplies blood to the lower body.
• What are the major arteries supplying the brain? The carotid arteries (common, internal, and external) and vertebral arteries supply the brain with oxygenated blood.
• What are the major veins that drain blood from the brain? The internal jugular veins drain deoxygenated blood from the brain into the superior vena cava.
• What is the function of the coronary arteries? The coronary arteries supply oxygenated blood to the heart muscle itself.
• Which major veins return blood from the lower limbs to the heart? The femoral vein and iliac vein merge into the inferior vena cava, returning blood to the heart.
• What is the origin of the subclavian artery? Right subclavian artery arises from the brachiocephalic trunk.Left subclavian artery arises directly from the aortic arch.
• Where is the pectoralis minor muscle located? The pectoralis minor is a thin, triangular muscle located beneath the pectoralis major in the anterior chest wall.
• hat is the function of the pectoralis minor muscle? Stabilises the scapula by drawing it anteriorly and inferiorly.Elevates ribs during forced inspiration when the scapula is fixed.
• What is the origin and course of the brachial artery? The brachial artery is a continuation of the axillary artery.It begins at the lower border of the teres major muscle and travels down the arm.It terminates in the cubital fossa, where it bifurcates into the radial and ulnar arteries.
• What are the two main arteries supplying the forearm? Radial artery – Supplies the lateral (thumb side) forearm.Ulnar artery – Supplies the medial (pinky side) forearm.
• What are the two main arterial arches in the hand? Superficial palmar arch – Formed mainly by the ulnar artery, with a contribution from the radial artery.Deep palmar arch – Formed mainly by the radial artery, with a contribution from the ulnar artery.
• What is the origin of the axillary artery? The axillary artery is a continuation of the subclavian artery.It begins at the lateral border of the first rib and continues until the lower border of the teres major muscle, where it becomes the brachial artery.
• What is the clinical significance of the Allen’s test? Allen’s test is used to assess collateral circulation between the radial and ulnar arteries before performing procedures like radial artery cannulation or harvesting for coronary artery bypass grafting (CABG).