Medical Terminology Simplified

Heart Valves

5–69 Label Figure 5–5 as you read the material about the heart valves and their

cusps, also called flaps.Four heart valves maintain the flow of blood in one direction

through the heart. The (1) tricuspid valveand the (2) mitral valveare situated be-

tween the upper and lower chambers and are attached to the heart walls by fibrous

strands called (3) chordae tendineae.The (4) pulmonary valveand the (5) aortic

valveare located at the exits of the ventricles.

Heart valves are composed of thin, fibrous cusps, covered by a smooth membrane

called the endocardium, and reinforced by dense connective tissue. The aortic, pul-

monary, and tricuspid valves contain (6) three cusps;the mitral valve contains

(7) two cusps.The purpose of the cusps is to open and permit blood to flow through

and seal shut to prevent backflow. The opening and closing of the cusps takes place

with each heartbeat.

5–70 To classify a heart abnormality, it is important to identify the part of the

organ in which the disorder occurs. A mitral valve murmur is caused by an incompe-

tent, or faulty,valve. This type of murmur occurs in the valvular structure of the

heart known as the ____________________ ____________________.

Frame 5–63to Frame 5–70

Cardiovascular System • CHAPTER 5 171

Normal vein with

competent valves

Varicose vein with

incompetent valves

Blood

Venous
blood flow
back to
the heart

Backflow

and pooling

of blood in

superficial

vein

Figure 5-4Healthy and unhealthy valves and veins. (A)Valve function in competent and
incompetent valves. (B)Varicose veins.

mitral valve

MĪ-trăl

A B