Chapter 9 Notes.docx - BIOL 4160 Chapter 9 Cardiac Physiology From lecture Cardiac Muscle More like skeletal muscle o Striated o Thin filaments contain

Chapter 9 Notes.docx - BIOL 4160 Chapter 9 Cardiac...

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BIOL 4160 Chapter 9: Cardiac Physiology From lecture: Cardiac Muscle More like skeletal muscle o Striated o Thin filaments contain troponin and tropomyosin o Clear length-tension relationship o T-tubules and moderately well- developed sarcoplasmic reticulum. Like oxidative skeletal muscle- possess lots of mitochondria and myoglobin, As in smooth muscle, calcium enters extracellularly and through voltage-gates DHP receptors (in T-tubule membrane). As in single-unit smooth muscle, cardiac muscle displays pacemaker (but not slow-wave) activity interconnected by gap junctions. Cardiac fibers exist in a branching network and action potentials last a relatively long time. 99% contractile cells, 1% pacemaker (autorhythmic) cells that do not contract. All body tissues constantly depend on the life-supporting blood flow the heart provides them by contracting or beating. The heart drives blood through the blood vessels for delivery to the tissues in enough amounts, whether the body is at rest or engaging in vigorous exercise. Pulmonary circulation - consists of a closed loop of vessels carrying blood between the heart and the lungs. Systemic circulation - a circuit of vessels carrying blood between the heart and all body systems. Although anatomically the heart is a single organ, the right and left sides of the heart functions as two separate pumps. The heart has right and left halves and has 4 chambers, an upper and a lower chamber within each. o Atria- upper chambers; receiving blood returning to the heart and transfer it to the lower chambers. o Ventricles- lower chambers; pump blood from the heart. Left- thicker muscle compared to right because it is the major driving force (except blood pressure) pumping blood to the rest of the body. Right- less muscular, pumps blood to lungs. The heart has 4 valves o Mitral valve and tricuspid valve- which control blood flow from the atria to the ventricles. Mitral valve - located between the left atrium and the left ventricle Bicuspid valve Left AV valve Tricuspid valve - located between the right atrium and the right ventricle Has 3 major banches right AV valve
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