- alveolus: tiny air sac at the end of a bronchiole in the lungs that provides surface area for gas exchange to occur
- aorta: brings oxygen-rich blood from the left ventricle to the body
- aorta: large blood vessel in mammals through which blood travels after it leaves the left ventricle
- artery: large blood vessel that carries blood from the heart to the tissues of the body
- atherosclerosis: condition in which fatty deposits called plaque build up on the inner walls of the arteries
- atrium: upper chamber of the heart that receives and holds blood that is about to enter the ventricle
- bronchus: passageway leading from the trachea to a lung
- capillary: smallest blood vessel; brings nutrients and oxygen to the tissues and absorbs carbon dioxide and waste products
- diaphragm: large, flat muscle at the bottom of the chest cavity that helps with breathing
- emphysema: disease in which the tissues of the lungs lose elasticity, making breathing very difficult
- hemoglobin: iron-containing protein in red blood cells that transports oxygen from the lungs to the tissues of the body
- inferior vena cava: vein that brings oxygen-poor blood from the lower part of the body to the right atrium
- larynx: structure in the throat containing the vocal cords
- left atrium: left upper chamber of heart; receives oxygen-rich blood from the pulmonary veins
- left ventricle: left lower chamber of heart; pumps blood out of the heart
- lymph: fluid lost by the blood into surrounding tissue
- lymphocyte: type of white blood cell that produces antibodies that help destroy pathogens
- myocardium: thick middle muscle layer of the heart; pumps blood through the circulatory system
- nicotine: stimulant drug in tobacco that increases heart rate and blood pressure
- pacemaker: small group of cardiac muscle cells in the right atrium that "set the pace" for the heart as a whole; also known as the sinoatrial node (SA)
- pharynx: muscular tube at the end of the throat that connects the mouth with the rest of the digestive tract, and serves as a passageway for air and food
- plasma: straw-colored fluid that makes up about 55% of blood
- platelet: cell fragment released by bone marrow that helps in blood clotting
- pulmonary arteries: bring oxygen-poor blood to the right or left lung
- pulmonary circulation: pathway of circulation between the heart and the lungs
- pulmonary valve: prevents blood from flowing back into the right ventricle after it has entered the pulmonary artery
- pulmonary veins: bring oxygen-rich blood from each of the lungs to the left atrium
- right atrium: right upper chamber of heart; receives oxygen-poor blood
- right ventricle: right lower chamber of heart; pumps blood out of the heart
- septum: divides the right side of the heart from the left side
- superior vena cava: large vein that brings oxygen-poor blood from the upper part of the body to the right atrium
- systemic circulation: pathway of circulation between the heart and the rest of the body except the lungs
- trachea: windpipe; tube through which air moves
- valve: flap of connective tissue between an atrium and a ventricle, or in a vein, that prevents backflow of blood
- vein: a blood vessel that returns blood to the heart
- ventricle: lower chamber of the heart that pumps blood out of the heart