BIOL 160 Chapter 33 Circulation PDF

BIOL160 Chapter 33 Circulation 1 Circulatory System Three major parts – Heart – Blood – Blood vessels 2 Diverse Functions 1. Transport of O2 and CO2 2. Distribution of nutrients 3. Transport of waste 4. Distribution of hormones 5...

BIOL160 Chapter 33 Circulation 1 Circulatory System Three major parts – Heart – Blood – Blood vessels 2 Diverse Functions 1. Transport of O2 and CO2 2. Distribution of nutrients 3. Transport of waste 4. Distribution of hormones 5. Regulation of body temperature 6. Prevent blood loss 7. Protect against disease 3 Evolution of the Vertebrate Heart Vertebrate hearts have muscular chambers called atria and ventricles Can have 2, 3, or 4 chambers – Atria collect blood Contract and deposit blood in ventricles – Ventricles distribute blood contract and discharge blood to body and lungs Evolution of the Vertebrate Heart Four chambered hearts – Most advanced – Have two atria and two ventricles – Separation of O2-rich and O2-poor blood maximizes O2 levels in blood – Examples: bird and mammal hearts Human Heart Function  Two types of blood vessels connect to heart chambers: – Veins: carry blood to atria – Arteries: carry blood away from ventricles Human Heart Function Made of two separate pumps  Right pump: made of right atrium and right ventricle deoxygenated blood  Left pump: made of left atrium and left ventricle oxygenated blood Right atrium receives O2-poor blood from body by superior and inferior vena cavae Right ventricle ejects O2-poor blood into pulmonary arteries to be oxygenated by lungs Left atrium receives O2-rich blood from lungs by pulmonary veins Left ventricle ejects O2-rich blood into aorta to be distributed to body tissues Heart Valves Heart valves insure one-way flow of blood through heart – Insure that O2-poor blood is sent to lungs and O2-rich blood is sent to body tissues – Atrioventricular valves: allow blood to flow from atria to ventricles, prevent back flow – Semilunar valves: allow blood to flow from ventricles to arteries, prevent back flow Blood flow Cardiac Muscle The heart is composed of cardiac muscle tissue Cardiac muscle cells are – Small, branched, and striated – Linked to one another via intercalated discs containing gap junctions – Gap junctions allow the electrical signals that trigger contractions to spread directly and rapidly from one muscle cell to the next This results in the coordinated, synchronous contraction of heart muscle The Cardiac Cycle The heart beats in a coordinated fashion: – Both atria contract and pump blood into ventricles – Both ventricles contract and pump blood into arteries – All chambers relax briefly before the cycle repeats – This cardiac cycle lasts less than 1 second