Ch. 7.8
Arteries
: Blood vessels that carry blood away from the heart. They are more muscular and elastic than other blood vessels. The largest artery is the aorta.
Aortic Valve
: A one-way valve located between the left ventricle and the aorta (the largest artery in the body). 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.
Plasma
The fluid portion of blood (approximately 55% of total volume). It is 90% water and contains dissolved substances like proteins (for clotting), nutrients, salts, gases, hormones, and enzymes.
Leukocytes
(White Blood Cells): Blood cells formed in the bone marrow and lymph tissue. Their main function is to fight infection by engulfing and destroying pathogens (phagocytosis) or developing antibodies.
Diastole
: A brief period of rest in the cardiac cycle, during which the atria relax and fill with blood returning from the body and lungs.
Mitral Valve
A one-way valve located between the left atrium and left ventricle. It closes when the left ventricle contracts, allowing blood to flow into the aorta and preventing backflow into the left atrium.
Left Ventricle
One of the two lower chambers of the heart. It receives blood from the left atrium and pumps the blood into the aorta for transport to the body cells.
Left Atrium
One of the two upper chambers of the heart. It receives oxygenated blood from the lungs.
Septum
: A muscular wall that separates the heart into a right side and a left side, preventing blood from moving between the two sides.
Blood
: The tissue that flows through the circulatory system, often called a tissue because it contains many kinds of cells. It transports oxygen, carbon dioxide, nutrients, waste products, heat, hormones, and antibodies.
Capillaries
: Tiny blood vessels that connect arterioles (smallest arteries) with venules (smallest veins). They have thin walls that allow oxygen and nutrients to pass through to the cells and allow carbon dioxide and metabolic products to enter the bloodstream.
Systole
: The period of ventricular contraction in the cardiac cycle, when the ventricles push blood into the pulmonary artery and the aorta.
Circulatory System (Cardiovascular System)
: The body's "transportation" system, consisting of the heart, blood vessels, and blood, which transports vital substances throughout the body.
Hemoglobin
: A complex protein within erythrocytes, composed of the protein molecule globin and the iron compound heme. It carries both oxygen and carbon dioxide.
Endocardium
: A smooth layer of cells that lines the inside of the heart and is continuous with the inside of blood vessels, allowing for the smooth flow of blood.
Pericardium
: A double-layered membrane, or sac, that covers the outside of the heart. It contains pericardial fluid to prevent friction as the heart beats.
Thrombocytes
Fragments or pieces of cells important for the clotting process. They form a sticky plug at an injury site and release chemicals to initiate the formation of a blood clot
Myocardium
: The thickest layer of the heart; the muscular middle layer responsible for contracting to pump blood.
Arrhythmias
Abnormal heart rhythms that occur when something interferes with the normal electrical conduction pattern of the heart. They can range from mild to life-threatening.
Pulmonary Valve
A one-way valve located between the right ventricle and the pulmonary artery. It closes after the right ventricle contracts, preventing blood from flowing back into the right ventricle.
Erythrocytes
(Red Blood Cells): Blood cells produced in the red bone marrow that contain hemoglobin. Their primary function is to carry oxygen from the lungs to the body cells and carbon dioxide from the cells back to the lungs.
Tricuspid Valve
A one-way valve located between the right atrium and the right ventricle. It closes when the right ventricle contracts, allowing blood to flow to the lungs and preventing backflow into the right atrium.
Right Atrium
One of the two upper chambers of the heart. It receives deoxygenated blood as it returns from the body cells.
Veins
: Blood vessels that carry blood back to the heart. They are thinner than arteries and most contain valves to prevent the backflow of blood.
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 it to the lungs for oxygenation.