The Heart Valves PDF

The Heart Valves Intended Describe the location of structure (cusps, chordae tendineae & papillary muscles) and Learning function (when open/closed) of the valves of the heart Outcome  Heart Valves Loading… Valves Atrioventricular Valves Loading...

The Heart Valves Intended Describe the location of structure (cusps, chordae tendineae & papillary muscles) and Learning function (when open/closed) of the valves of the heart Outcome  Heart Valves Loading… Valves Atrioventricular Valves Loading… Tricuspid Valve Superior view of valves  Heart Dissection Showing Valves  Semilunar Valves Structure and Function Summary – Valves of the Heart The valves of the heart are structures which ensure blood flows in only one direction. They are composed of connective tissue and endocardium (the inner layer of the heart). There are four valves of the heart, which are divided into two categories: Atrioventricular valves: The tricuspid valve and mitral (bicuspid) valve. They are located between the atria and corresponding ventricle. Semilunar valves: The pulmonary valve and aortic valve. They are located between the ventricles and their corresponding artery, and regulate the flow of blood leaving the heart. Summary - Atrioventricular Valves The tricuspid and bicuspid valves are termed atrioventricular (AV) valves. When an AV valve is open, the rounded ends of the cusps project into the ventricle. Loading… When the ventricles are relaxed, the papillary muscles are relaxed, the chordae tendineae are slack, and blood moves from a higher pressure in the atria to a lower pressure in the ventricles through open AV valves When the ventricles contract, the pressure of the blood drives the cusps upward until their edges meet and close the opening. At the same time, the papillary muscles contract, which pulls on and tightens the chordae tendineae. This prevents the valve cusps from everting (opening into the atria) in response to the high ventricular pressure. If the AV valves or chordae tendineae are damaged, blood may regurgitate (flow back) into the atria when the ventricles contract. Summary - Semi lunar Valves The aortic and pulmonary valves are known as the semilunar (SL) valves because they are made up of three crescent moon–shaped cusps Each cusp attaches to the arterial wall by its convex outer margin. The SL valves allow ejection of blood from the heart into arteries but prevent backflow of blood into the ventricles. The free borders of the cusps project into the lumen of the artery. When the ventricles contract, pressure builds up within the chambers. The semilunar valves open when pressure in the ventricles exceeds the pressure in the arteries, permitting ejection of blood from the ventricles into the pulmonary trunk and aorta As the ventricles relax, blood starts to flow back toward the heart. This backflowing blood fills the valve cusps, which causes the free edges of the semilunar valves to contact each other tightly and close the opening between the ventricle and artery