Ch. 7.8 Circulatory System Key Terms
Aortic valve
The valve between the left ventricle and the aorta; it closes after the left ventricle contracts to prevent blood from flowing back into the ventricle.
Arrhythmias
Abnormal heart rhythms caused by problems in the heart’s electrical conduction system; they range from mild to life-threatening.
Arteries
Blood vessels that carry blood away from the heart; they are strong, elastic, and include the aorta and its branches.
Blood
A tissue made of plasma and blood cells that transports oxygen, carbon dioxide, nutrients, hormones, waste products, and heat throughout the body.
Capillaries
Tiny, one-cell-thick blood vessels that connect arterioles and venules; they allow the exchange of oxygen, nutrients, and waste between blood and the body’s cells.
Systole
The phase of the cardiac cycle when the ventricles contract and pump blood to the lungs and body.
Circulatory system
The body’s “transportation system,” made of the heart, blood, and blood vessels; it moves oxygen, carbon dioxide, nutrients, hormones, and wastes.
Diastole
The period of rest in the cardiac cycle when the heart relaxes and the ventricles fill with blood.
Endocardium
The smooth inner lining of the heart that is continuous with blood vessel linings and allows smooth blood flow.
Erythrocytes
Red blood cells made in the red bone marrow; they carry oxygen and carbon dioxide using hemoglobin.
Hemoglobin
A complex protein containing globin and heme that binds oxygen and carbon dioxide; gives blood its red color.
Left atrium
The upper left chamber of the heart that receives oxygenated blood from the lungs via the pulmonary veins.
Left ventricle
The lower left chamber that pumps oxygenated blood into the aorta to deliver it to the body.
Leukocytes
White blood cells formed in bone marrow and lymph tissue; they fight infection through phagocytosis and immune responses.
Mitral valve
The valve between the left atrium and left ventricle; it prevents blood from flowing backward during ventricular contraction.
Myocardium
The thick, muscular middle layer of the heart responsible for pumping blood.
Pericardium
A double-layered sac surrounding the heart; it contains fluid that reduces friction as the heart beats.
Plasma
The liquid component of blood (90% water) that carries proteins, nutrients, hormones, electrolytes, and waste products.
Pulmonary valve
The valve between the right ventricle and pulmonary artery; it prevents backflow into the right ventricle after contraction.
Right atrium
The upper right chamber of the heart that receives deoxygenated blood from the body via the superior and inferior vena cava.
Right ventricle
The lower right chamber that pumps deoxygenated blood into the pulmonary artery and to the lungs for oxygenation.
Septum
The muscular wall dividing the heart into right and left sides; prevents oxygenated and deoxygenated blood from mixing.
Thrombocytes
Also called platelets; cell fragments that help form clots to stop bleeding
Tricuspid valve
The valve between the right atrium and right ventricle; it prevents backflow into the right atrium during contraction.
Veins
Blood vessels that carry blood back to the heart; they have thinner walls than arteries and many contain valves to prevent backflow.