Ch. 7.8 Circulatory System Key Terms
A semilunar valve located between the left ventricle and the aorta. It opens to allow oxygenated blood to be pumped into the systemic circulation and closes to prevent backflow into the ventricle.
Aortic valve
he complete system that circulates blood and lymph throughout the body, consisting of the heart, blood vessels (arteries, veins, capillaries), and the blood itself.
Circulatory system
The upper left chamber of the heart. It receives oxygenated blood from the lungs and pumps it through the mitral valve into the left ventricle.
Left atrium
A fluid-filled sac that surrounds the heart and the roots of the great blood vessels. It protects the heart, anchors it in place, and prevents overexpansion.
Pericardium
A muscular wall that divides the heart into a right side and a left side, preventing the mixing of deoxygenated and oxygenated blood.
Septum
Abnormal, irregular, or rapid heart rhythms. They occur when the electrical impulses in the heart don't work correctly, causing the heart to beat too fast, too slow, or irregularly.
Arrhythmias
The phase of the cardiac cycle when the heart muscle relaxes and the chambers (atria and ventricles) fill with blood. It is the period of lowest pressure.
Diastole
The lower left chamber of the heart. It is the heart's main pumping chamber, ejecting oxygenated blood through the aortic valve into the aorta (and the rest of the body). It has the thickest wall of any chamber.
Left ventricle
The liquid component of blood, making up about 55% of its volume. It is primarily water but contains dissolved proteins, glucose, clotting factors, mineral ions, hormones, and carbon dioxide
Plasma
The phase of the cardiac cycle when the heart muscle contracts, forcefully pushing blood out of the ventricles and into the arteries. It is the period of highest pressure.
Systole
Large blood vessels that carry oxygenated blood away from the heart to the rest of the body's tissues. They are under high pressure.
Arteries
The thin, smooth membrane that lines the interior of the heart's chambers and valves.
Endocardium
White blood cells (WBCs). These are the cells of the immune system that defend the body against infectious disease and foreign invaders.
Leukocytes
The upper right chamber of the heart. It receives deoxygenated blood from the systemic circulation (the body) and pumps it through the tricuspid valve into the right ventricle.
Right atrium
Also known as platelets. These are small, irregular, cell fragments in the blood whose main function is to prevent bleeding by forming blood clots.
Thrombocytes
The fluid tissue that circulates throughout the body, delivering oxygen and nutrients to cells and removing waste products. It is composed of plasma, erythrocytes, leukocytes, and thrombocytes.
Blood
An iron-containing protein found within erythrocytes. Its primary function is to bind to and transport oxygen and, to a lesser extent, carbon dioxide.
Hemoglobin
A bicuspid valve located between the left atrium and the left ventricle. It prevents the backflow of oxygenated blood into the left atrium when the ventricle contracts.
Mitral valve
A semilunar valve located between the right ventricle and the pulmonary artery. It opens to allow deoxygenated blood to be pumped toward the lungs and closes to prevent backflow.
Pulmonary valve
A valve with three flaps (cusps) located between the right atrium and the right ventricle. It prevents the backflow of deoxygenated blood into the right atrium when the ventricle contracts.
Tricuspid valve
The smallest and most numerous blood vessels, forming a network between the arteries and veins. This is where the exchange of oxygen, nutrients, and waste occurs between the blood and the tissue cells.
Capillaries
Red blood cells (RBCs). These are biconcave cells that contain hemoglobin and are responsible for transporting oxygen from the lungs to the body tissues.
Erythrocytes
The thick, muscular middle layer of the heart wall. Its powerful contractions are responsible for pumping blood throughout the circulatory system.
Myocardium
The lower right chamber of the heart. It pumps deoxygenated blood through the pulmonary valve into the pulmonary artery, which carries the blood to the lungs for oxygenation.
Right ventricle
Blood vessels that carry deoxygenated blood toward the heart from the capillaries and tissues. They are under low pressure and often contain valves to prevent backflow.
Veins