Ch. 7.8 Circulatory System Key Terms
Arteries
Blood vessels that carry blood away from the heart. They are muscular and elastic.
Blood
The fluid tissue that flows through the circulatory system; it consists of plasma and formed elements (erythrocytes, leukocytes, thrombocytes).
Veins
Blood vessels that carry blood back to the heart. Most contain valves to prevent backward flow of blood.
Right Ventricle
The lower right chamber of the heart that receives blood from the right atrium and pumps the blood into the pulmonary artery (to the lungs for oxygen).
Endocardium
The smooth, innermost layer of cells that lines the inside of the heart chambers and is continuous with the inside of blood vessels, allowing for the smooth flow of blood.
Circulatory System
Also known as the cardiovascular system; it consists of the heart, blood vessels, and blood, functioning as the transportation system of the body.
Plasma
The fluid portion of blood (approximately 90% water) that contains dissolved or suspended substances like proteins, nutrients, salts, and waste products.
Septum
A muscular wall that separates the heart into a right side and a left side, preventing blood from mixing.
Mitral Valve
The one-way valve located between the left atrium and the left ventricle; also called the bicuspid valve.
Myocardium-
The thickest layer of the heart wall; the muscular middle layer.
Hemoglobin
-A complex protein in erythrocytes that is composed of the protein globin and the iron compound heme. It carries both oxygen and carbon dioxide.
Pulmonary Valve
The one-way valve located between the right ventricle and the pulmonary artery. It closes after contraction, preventing blood from flowing back into the ventricle.
Leukocytes
White blood cells (WBCs). They are formed in the bone marrow and lymph tissue, and their main function is to fight infection (e.g., via phagocytosis).
Erythrocytes
-Red blood cells (RBCs). They are produced in the red bone marrow, lack a nucleus, contain hemoglobin, and function to carry oxygen and carbon dioxide.
Capillaries
Tiny, thin-walled blood vessels that connect arterioles with venules. Their thin walls allow for the exchange of oxygen, nutrients, and waste products between blood and body cells.
Left Ventricle
The lower left chamber of the heart that receives blood from the left atrium and pumps the oxygenated blood into the aorta for transport to the body cells.
Right Atrium
The upper right chamber of the heart that receives deoxygenated blood as it returns from the body cells (via the superior and inferior vena cava).
Tricuspid
The one-way valve located between the right atrium and the right ventricle.
Hemoglobin
A complex protein in erythrocytes that is composed of the protein globin and the iron compound heme. It carries both oxygen and carbon dioxide.
Diastole
A brief period of rest in the cardiac cycle when the atria are filling with blood.
Pericardium
A double-layered membrane, or sac, that covers the outside of the heart. It contains lubricating pericardial fluid to prevent friction.
Systole
A period of ventricular contraction in the cardiac cycle, during which blood is pushed out into the pulmonary artery and the aorta.
Thrombocytes
-Also called platelets. They are cell fragments formed in the bone marrow and are important for the clotting process (which stops bleeding).
Aortic Valve-
The one-way valve located between the left ventricle and the aorta (the largest artery). It closes when the left ventricle finishes contracting, preventing blood from flowing back into the ventricle.
Arrhythmias
Abnormal heart rhythms caused by interference with the heart's normal electrical conduction pattern.