Ch. 7.8 Circulatory System Key Terms
Aortic Valve
The semilunar valve located between the left ventricle and the aorta. It prevents the backflow of blood from the aorta back into the ventricle during diastole.
Circulatory System
The biological system that moves blood throughout the body to transport oxygen, nutrients, hormones, and waste. It is composed of the heart, blood vessels, and blood.
Left Atrium
The upper left chamber of the heart. It receives oxygenated blood from the lungs via the pulmonary veins.
Pericardium
The protective, double-layered sac or membrane that surrounds the heart.
Septum
The muscular wall that separates the right and left sides of the heart, preventing the mixing of deoxygenated and oxygenated blood.
Arrhythmias
Abnormalities or disturbances in the rhythm of the heartbeat. They occur when the electrical impulses that coordinate heartbeats don't work properly, causing the heart to beat too fast, too slow, or irregularly.
Diastole
The phase of the cardiac cycle when the heart muscles relax and the chambers fill with blood. This corresponds to the lower number in a blood pressure reading.
Left Ventricle
The lower left chamber of the heart. It has the thickest muscular wall (myocardium) and pumps oxygenated blood through the aortic valve into the aorta for distribution to the entire body.
Plasma
The straw-colored, liquid matrix of the blood, making up over half of its volume. It is mostly water, carrying dissolved proteins, glucose, electrolytes, hormones, and carbon dioxide.
Systole
The phase of the cardiac cycle when the heart's ventricles contract and forcefully push blood out into the arteries (the pulmonary artery and the aorta). This corresponds to the higher number in a blood pressure reading.
Arteries
Large, thick-walled blood vessels that carry oxygenated blood away from the heart to the rest of the body's tissues
Endocardium
The thin, smooth innermost layer of tissue that lines the four chambers and valves of the heart.
Leukocytes
Cells of the immune system that protect the body against infection and disease.
Pulmonary Valve
The semilunar valve located between the right ventricle and the pulmonary artery. It controls blood flow to the lungs.
Thrombocytes
Small, irregular cell fragments in the blood that are essential for initiating blood clotting and wound repair.
Blood
The fluid connective tissue that circulates throughout the body, consisting of plasma and formed elements. It transports oxygen, nutrients, hormones, and waste products.
Erythrocytes
The most common type of blood cell. They contain hemoglobin and are primarily responsible for transporting oxygen from the lungs to the tissues.
Mitral Valve
A valve situated between the left atrium and the left ventricle. It prevents the backflow of blood into the atrium when the ventricle contracts.
Right Atrium
The upper right chamber of the heart. It receives deoxygenated blood returning from the body via the superior and inferior vena cava.
Tricuspid Valve
The valve situated between the right atrium and the right ventricle. It has three cusps (flaps) and prevents the backflow of blood into the atrium.
Capillaries
: The smallest and most numerous blood vessels, forming a fine network connecting the smallest arteries (arterioles) to the smallest veins (venules). This is the site of gas and nutrient exchange between the blood and the tissue cells.
Hemoglobin
An iron-containing protein molecule found within erythrocytes that is responsible for binding and carrying oxygen.
Myocardium
The thick, muscular middle layer of the wall of the heart. It is the muscle tissue responsible for the heart's pumping action.
Right Ventricle
The lower right chamber of the heart. It pumps deoxygenated blood to the lungs through the pulmonary valve.
Veins
Blood vessels that carry deoxygenated blood toward the heart from the body's tissues