ireland3e_lecture_ch12

ireland3e_lecture_ch12 - Chapter 12 The Cardiovascular...

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10/12/2011 1 Chapter 12 The Cardiovascular System The Cardiovascular System The cardiovascular system transports blood, nutrients, wastes, and dissolved gases to and from the tissues it includes the heart, blood vessels, and blood it also works together with the respiratory system to deliver oxygen and remove carbon dioxide from cells in the body
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10/12/2011 2 The Heart The heart is a three-layered, four-chambered, two-cycle organ it resides in the center of the thoracic cavity The pericardium is a serous membrane, secreting a lubricating fluid that surrounds the heart and allows it to beat without causing damage to itself The walls of the heart are composed of three layers epicardium myocardium muscle of the heart, contracts to create heartbeats endocardium The Heart
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10/12/2011 3 The Heart The heart has four chambers two ventricles the left ventricle pushes blood throughout the body the less muscular right ventricle pushes blood only to the nearby lungs two atria smaller, thin-walled chambers sit atop the thick-walled, muscular ventricles they serve as holding tanks for blood after it returns from the body or lungs they receive blood from large veins and direct it into the ventricles The two sides of the heart are divided by a thick wall called the septum The Heart
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10/12/2011 4 Heart Valves Atrioventricular valves between the atria and the ventricles open to allow blood to pass and then close when the chamber contracts to pump the tricuspid valve is found in the right ventricle the bicuspid, or mitral valve, is found in the left ventricle Blood Flow Blood enters the heart twice during one complete circuit of the cardiovascular system Blood enters the right atrium from the superior and inferior vena cava and the cardiac sinus, and then drops through the tricuspid atrioventricular valve into the right ventricle, which pumps blood to the lungs Blood that returns from the lungs enters the left atrium and drops through the mitral valve into the left ventricle, which pumps the blood throughout the body
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10/12/2011 5 The Cardiac Cycle Blood Pressure At the beginning of the cardiac cycle, the heart is in diastol where the ventricles have relaxed after their recent contraction, and their volume has increased diastolic pressure is the force your blood exerts on the walls of your closed circulatory system while the heart is in complete diastole (relaxation) The two atria then undergo systole and force the remaining atrial blood into the ventricles systolic pressure measures the force of left ventricle contraction, which pushes blood through the circulatory system As the ventricles contract, the atria relax After a brief ventricular contraction, the entire heart relaxes The force created by the left ventricle generates the pulse we can feel and the blood pressure that is measured at the doctor’s office High blood pressure is loosely defined as a blood pressure reading of 140/90 or above
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This note was uploaded on 12/26/2011 for the course BSC 2023 taught by Professor Staff during the Fall '08 term at FIU.

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ireland3e_lecture_ch12 - Chapter 12 The Cardiovascular...

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