Chapter 19 - Section 19.2 - Study Guide - Assess Your Learning Outcomes - Page 740: 6

The heart valves have distinct structural differences that correspond to their specific roles in regulating blood flow. Additionally, the papillary muscles and tendinous cords are important structures within the heart that are closely associated with the valves. Let's delve into these aspects: **Structural Differences Between Valves:** 1. **Aortic Valve and Pulmonary Valve (Semilunar Valves):** - These valves consist of three semilunar cusps (leaflets) that are thin and shaped like half-moons. - The cusps are attached to the wall of the aorta and pulmonary artery at their bases. During ventricular contraction, these cusps open to allow blood to be ejected from the ventricles into the respective arteries. When the ventricles relax, the cusps close to prevent backflow. 2. **Tricuspid Valve:** - The tricuspid valve has three leaflets or cusps, similar to the aortic and pulmonary valves. - It is located between the right atrium and right ventricle. - The tricuspid valve prevents blood from flowing back into the right atrium during ventricular contraction. 3. **Mitral Valve:** - The mitral valve, also known as the bicuspid valve, consists of two leaflets. - It is located between the left atrium and left ventricle. - The mitral valve prevents blood from flowing back into the left atrium during ventricular contraction. **Anatomy and Function of Papillary Muscles and Tendinous Cords:** Papillary muscles and tendinous cords are structures within the ventricles that are closely associated with the atrioventricular valves (tricuspid and mitral valves). They play a crucial role in preventing the valves from being pushed into the atria when the ventricles contract, which could lead to regurgitation (backflow) of blood. 1. **Papillary Muscles:** - Papillary muscles are small, muscular projections located within the ventricles. - They attach to the ventricular walls and are connected to the leaflets of the atrioventricular valves by tendinous cords. - When the ventricles contract, the papillary muscles also contract, pulling on the tendinous cords. - This action creates tension in the tendinous cords and prevents the valve leaflets from being forced into the atria, ensuring that blood flows in the correct direction. 2. **Tendinous Cords (Chordae Tendineae):** - Tendinous cords are strong, fibrous strings that connect the papillary muscles to the leaflets of the atrioventricular valves. - These cords transmit the force generated by the papillary muscles to the valve leaflets. - They help maintain the proper closure of the valves during ventricular contraction, preventing regurgitation of blood into the atria. In summary, the structural differences between the heart valves reflect their specific functions in regulating blood flow. The papillary muscles and tendinous cords are integral to the functioning of the atrioventricular valves by preventing valve prolapse and ensuring efficient one-way blood flow from the atria to the ventricles.

The heart valves have distinct structural differences that correspond to their specific roles in regulating blood flow. Additionally, the papillary muscles and tendinous cords are important structures within the heart that are closely associated with the valves. Let's delve into these aspects: **Structural Differences Between Valves:** 1. **Aortic Valve and Pulmonary Valve (Semilunar Valves):** - These valves consist of three semilunar cusps (leaflets) that are thin and shaped like half-moons. - The cusps are attached to the wall of the aorta and pulmonary artery at their bases. During ventricular contraction, these cusps open to allow blood to be ejected from the ventricles into the respective arteries. When the ventricles relax, the cusps close to prevent backflow. 2. **Tricuspid Valve:** - The tricuspid valve has three leaflets or cusps, similar to the aortic and pulmonary valves. - It is located between the right atrium and right ventricle. - The tricuspid valve prevents blood from flowing back into the right atrium during ventricular contraction. 3. **Mitral Valve:** - The mitral valve, also known as the bicuspid valve, consists of two leaflets. - It is located between the left atrium and left ventricle. - The mitral valve prevents blood from flowing back into the left atrium during ventricular contraction. **Anatomy and Function of Papillary Muscles and Tendinous Cords:** Papillary muscles and tendinous cords are structures within the ventricles that are closely associated with the atrioventricular valves (tricuspid and mitral valves). They play a crucial role in preventing the valves from being pushed into the atria when the ventricles contract, which could lead to regurgitation (backflow) of blood. 1. **Papillary Muscles:** - Papillary muscles are small, muscular projections located within the ventricles. - They attach to the ventricular walls and are connected to the leaflets of the atrioventricular valves by tendinous cords. - When the ventricles contract, the papillary muscles also contract, pulling on the tendinous cords. - This action creates tension in the tendinous cords and prevents the valve leaflets from being forced into the atria, ensuring that blood flows in the correct direction. 2. **Tendinous Cords (Chordae Tendineae):** - Tendinous cords are strong, fibrous strings that connect the papillary muscles to the leaflets of the atrioventricular valves. - These cords transmit the force generated by the papillary muscles to the valve leaflets. - They help maintain the proper closure of the valves during ventricular contraction, preventing regurgitation of blood into the atria. In summary, the structural differences between the heart valves reflect their specific functions in regulating blood flow. The papillary muscles and tendinous cords are integral to the functioning of the atrioventricular valves by preventing valve prolapse and ensuring efficient one-way blood flow from the atria to the ventricles.