Ch. 7.8 Circulatory System Key Terms
Aortic valve
A valve located between the left ventricle and the aorta. It closes when the left ventricle is finished contracting, allowing blood to flow into the aorta and preventing blood from flowing back into the left ventricle.
Circulatory system
Often referred to as the "transportation" system of the body. It consists of the heart, blood vessels, and blood, and transports nutrients, oxygen, hormones, and antibodies, while carrying away waste products.
Left atrium
One of the two upper chambers of the heart.
Pericardium
A loose, double-layered membrane or sac that covers the outside of the heart.
Septum
A muscular wall that separates the heart into a right side and a left side, preventing blood from moving between the right and left sides.
Arrhythmias
Abnormal heart rhythms or heartbeats.
Diastole
The period of relaxation during the cardiac cycle when the atria are filling, systole ends, and the ventricles relax.
Left ventricle
One of the two lower chambers of the heart. It receives oxygenated blood from the left atrium and pumps the blood into the aorta for transport to the body cells.
Plasma
The fluid, straw-colored part of the blood that is about 90% water. It carries dissolved or suspended substances, including proteins, nutrients, and waste products.
Systole
The period of contraction during the cardiac cycle when the atria and then the ventricles contract, pushing blood into the arteries.
Arteries
Blood vessels that carry blood away from the heart.
Endocardium
The innermost layer of tissue forming the heart, lining the inside of the heart, and is continuous with the inside of blood vessels.
Leukocytes
The white blood cells whose main function is to fight infection by ingesting pathogens (phagocytosis) and by producing antibodies.
Pulmonary valve
A valve located between the right ventricle and the pulmonary artery.
Thrombocytes
Small, irregular fragments or pieces of cells, also called platelets, that are important for the clotting process to stop bleeding.
Blood
The fluid that flows through the circulatory system.
Erythrocytes
The red blood cells responsible for carrying oxygen and carbon dioxide via the protein hemoglobin.
Mitral valve
A valve located between the left atrium and the left ventricle.
Right atrium
One of the two upper chambers of the heart. It receives deoxygenated blood as it returns from the body cells.
tricuspid valve
A valve located between the right atrium and the right ventricle. It closes when the right ventricle contracts, preventing blood from flowing back into the right atrium.
Capillaries
The tiniest blood vessels that connect arteries with venules.
Hemoglobin
A protein molecule contained in red blood cells that is composed of a protein component and a complex iron compound. It is responsible for carrying oxygen and carbon dioxide.
Myocardium
The middle layer of heart muscle, which performs the work of the heart.
Right ventricle
One of the two lower chambers of the heart. It receives blood from the right atrium and pumps the blood into the pulmonary artery, which carries the blood to the lungs for oxygen.
Veins
Blood vessels that carry blood back to the heart.