Heart

The Cardiovascular System The heart beats about 100,000 times/day, 35 million times/year In a resting adult the heart rate is about 75 beats/minute Cardiology is the study of the normal heart and the diseases of the heart It is between the 2 lungs in the thoracic cavity Myocardium – cardiac muscle tissue, responsible for the pumping action of the heart

Heart It has 4 chambers 2 Atria at the top 2 ventricles at the bottom Partition between the left ventricle and the right ventricle is the interventricular septum

Valves Valves prevent blood from flowing the wrong direction Sometimes valves must be replaced The aortic valve is the most commonly replaced heart valve

Conduction system of the heart Pacemaker – 1% of the cardiac muscles fibers are different from all other. They can generate action potentials over and over and do so in a rhythmical pattern. They set the rhythm for the heart and form the conduction system which ensures the cardiac chambers to contract in a coordinated manner.

Artificial Pacemaker A device that sends out small electrical currents to stimulate the heart to contract. A pacemaker consists of a battery and impulse generator and is usually implanted beneath the skin just inferior to the clavicle.

Monitoring A recording of the electrical changes that accompany the heartbeat is called an electrocardiogram (EKG) Blood pressure – Systolic over Diastolic pressure. Systolic refers to the stage of contraction. Diastolic refers to the phase of relaxation. A normal adult blood pressure is 120/80.

Diseases Congestive heart failure – the heart is failing to pump. If the left side fails – it can’t pump out all the blood and it backs up into the lungs. The result is pulmonary edema – fluid accumulation in the lungs that can lead to suffocation. If the right side fails – blood backs up in the systemic vessels. The result is peripheral edema – swelling in the feet and ankles. Common causes – coronary artery disease, long-term high blood pressure, and valve disorders.

Exercise and the Heart Aerobic exercise – activity that works large body muscles for at least 20 minutes, elevates cardiac output and accelerates metabolic rate. Regular exercise helps to reduce blood pressure, anxiety, and depression and controls weight.