Circulatory System

• Hemolymph


  A mixture of blood and tissue fluid that is the circulating fluid in an open circulatory system
• Atrium


  A chamber of the the heart that receives blood from the body
• Ventricle


  A chamber of the heart that pumps blood to the body
• Septum


  A wall of tissue that divides a body cavity or structure into smaller parts
• Pulmonary circuit


  The part of the circulatory system that delivers blood to the lungs
• Systemic circuit


  The part of the circulatory system that delivers blood around the body
• Serum


  The fluid that results when the cells, platelets, and fibrinogen have been removed from the whole blood
• Pus


  A yellowish-white fluid formed in infected tissue, consisting of white blood cells and cellular debris
• Platelet


  A cell fragment in the blood that is necessary for blood clotting
• Leukocyte


  A white blood cell
• Erythrocyte


  A red blood cell
• Anemia


  A condition of a low erythrocyte (red blood cell) count or a low hemoglobin level, which leads to low oxygen levels
• Aorta


  The largest blood vessel in the body, connected directly to the heart; the aorta branches into arteries that carry oxygenated blood to the body tissues
• Arteriole


  The smallest artery, with smooth muscle in its walls
• Vasodilation


  An increase in the diameter (dilation) of arterioles that increases the blood flow to tissues
• Vasoconstriction


  A decrease in the diameter of arterioles that decreases the blood flow to tissues
• Venule


  The smallest vein; formed by the merging of capillaries
• Systolic pressure


  The blood pressure in the arteries when the heart contracts
• Diastolic pressure


  The blood pressure in the arteries when the heart relaxes
• Lymph


  Tissue fluid collected in lymph vessels and returned to the blood
• Lymph node


  An enlargement in the lymph vessels that acts as a filter to remove bacteria and foreign particles
• Spleen


  The largest organ of the lymphatic system; acts as a filter and a reservoir of erythrocytes and leukocytes
• Thymus


  A glandular organ of the lymphatic system; secrets hormones to promote the maturity of lymphocytes
• Pericardium


  A fibrous sac that encloses the heart and great vessels
• Coronary blood vessel


  A blood vessel that circulates blood to and from the muscle cells of the heart
• Semilunar valve


  The valve located between the left ventricle and the aorta and the right ventricle and the pulmonary arteries to prevent the backflow of blood when the ventricles relax
• Atrioventricular valve


  The mitral valve, and the tricuspid valve, which are situated between the atria and the ventricles, and prevent backflow from the ventricles into the atria during systole
• Chordae tendineae


  Tendons that support the atrioventricular valves
• Cardiac cycle


  The contractions and relaxations of the heart muscles during a complete heartbeat
• Diastole


  The period of the cardiac cycle when the ventricles are relaxed; blood fills the ventricles
• Systole


  The period of the cardiac cycle when the ventricles contract; blood is ejected from the ventricles
• Myogenic muscle


  Muscle that can contract and relax without input from an external source
• Sinoatrial (SA) node


  A mass of muscle and nerve cells in the right atrium; initiates the heartbeat and maintains the regular rhythm
• Atrioventricular (AV) node


  A mass od conducting cells that transmits the signals from the sinoatrial (SA) node to the muscles of the ventricles
• Purkinje fibre


  A conducting fibre that carries the electrical signals from the atrioventricular (AV) node to the muscle cells of the ventricles
• Electrocardiograph


  A device that detects the electrical activity of the heart through electrodes placed on the body's surface
• Arteriosclerosis


  The loss of elasticity and hardening of the arteries that may be caused by a number of factors including hypertension, age, and plaque build up
• Plaque


  Deposits of fat, cholesterol, calcium, and other materials on and in the walls if the arteries
• Atherosclerosis


  The hardening of the arteries due to a build of plaque on or inside the walls of the arteries; atherosclerosis is the most common form of arteriosclerosis
• Coronary artery disease


  The buildup of plaque on or inside the walls of the coronary arteries