(30 points) Valvular stenosis and valvular regurgitation are diseases of the hea
ID: 3523479 • Letter: #
Question
(30 points) Valvular stenosis and valvular regurgitation are diseases of the heart valves that can affect blood flow and cardiovascular function. a. Explain how heart valves normally work to ensure single-direction blood flow and why that is important to normal cardiovascular function. Include an explanation of the forces involved in causing the valves to open and close. b. Describe how either of these conditions in the mitral valve would affect blood flow and cardiac output. c. These conditions may lead to secondary pulmonary hypertension (high blood pressure in the pulmonary circuit) and pulmonary edema (fluid build up in and around the lungs). Explain why these secondary diseases would occur and why they would occur in the pulmonary, rather than the systemic, circuit. Incorporate factors that affect blood flow and pressure, as well as capillary exchange, in your answer.
Explanation / Answer
A. Heart valves function to ensure a one-way flow of blood through a heart. The valves are not made of muscle, but rather are composed of sheets of tough connective tissue (leaflets) that acts like flaps. The heart valves open and close passively because of pressure differences on either side of the valve. When pressure is greater behind the valve, the leaflets are blown open and the blood flows through the valve. However, when pressure is greater infront of the valve, the leaflets snap shut and blood flow is stopped. The atrioventricular valves(AV) valves which separate the atria from the ventricles , allow blood to flow from the atria to the ventricles but prevent flow in the opposite direction. The right AV valve is tricuspid valve and the left AV valve is mitral valve. The opening and closing of AV valves is dependent on pressure difference between the atria and ventricles. When ventricle relax atrial pressure exceeds ventricular pressure, the AV valves are pushed open and blood flows into the ventricles. When ventricles contract ventricular pressure exceeds atrial pressure causing the AV valves to snap shut. The semilunar valves are one way valves that separate the ventricles from the major arteries. The aortic valve separates the left ventricle from the aorta while pulmonary valve separates the right ventricle ftom the pulmonary artery.
B. Mitral regurgitation is the abnormal backward flow of blood from the left ventricle to the left atrium due to either disease of the mitral valve apparatus, known as organic or due to dilation of the mitral valve annulus from left atrium or left ventricular disease, known as functional. When blood abnormally flows backward the volume of both chamber increases. Because a significant volume of blood is flowing retrograde forward cardiac output decreases despite the left ventricular ejection fraction apperaing normal.
C. The stenosis can occur in the supravalvular region at the valve annulus thus it leads to pulmonary hypertension .
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