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“Learning is not child’s play; we cannot learn without pain.” Aristotle, Greek philosopher. THE HEART. I. Location. A. Cavity between lungs, 2/3 left of midsagittal 1. About the same size as fist. II. Pericardial sac (pericardium ). A. parietal pericardium 1. External (outer) layer
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“Learning is not child’s play; we cannot learn without pain.” • Aristotle, Greek philosopher
I. Location • A. Cavity between lungs, 2/3 left of midsagittal • 1. About the same size as fist
II. Pericardial sac (pericardium) • A. parietal pericardium • 1. External (outer) layer • B. visceral pericardium (epicardium) • 1. On heart wall • C. pericardial cavity and pericardial fluid • 1. Reduce friction
III. The heart wall • A. epicardium (see above) • 1. Penetrated by fat • B. myocardium- muscle • C. endocardium- epithelial tissue inner lining
IV. Heart chambers • A. 4 chambers • 1. Atrium (left and right atria) • a. receive blood from veins • b. divided by the septum • c. fossa ovalis • 2. Ventricles (left and right) • a. muscular pumps • b. divided by the interventricular septum
V. Heart Valves • A. Two atrioventricular valves (AV valves) • 1. Tricuspid valve- between right atrium and ventricle • 2. Bicuspid (mitral) valve- between left atrium and ventricle • a. heavier and stronger • b. chordae tendinae and papillary muscles stop valves from going too far
3. Pulmonary semilunar valve- between the pulmonary artery and right ventricle • 4. Aortic semilunar valve- between aorta and left ventricle
PHYSIOLOGY OF THE HEART III. The Conducting System (Electricity) A. Sinoatrial Node (SA)- PACEMAKER 1. Located in wall of right atrium 2. Specialized myocardial cells 3. Sends impulse to both atria, causes them to contract
B. Atrioventricular Node (AV node) • 1. Located at base of right atrium • 2. Delay of 0.1 seconds before impulse is sent • C. Atrioventricular bundle- middle of septum • 1. Impulse from AV node goes down bundle to base of heart • 2. It then travels up the sides of the ventricles through the Purkinje network causing the ventricles to contract from the bottom up.
IIV. Rate of Heart Beat • A. Some factors: age, sex, position of body, physical activity, temperature, thought processes • B. Rate is high at birth (100-140bpm)- declines steadily until average is reached • 1. Greater in females
V.TheElectrocardiogram(EKG) • A. amplifies the electric current produced by the heart
p=depolarization of atria qrs=depolarization of ventricles t=repolarization of ventricles
VI. Heart Disorders • Risk factors:cholesterol, hypertension, smoking, obesity, lack of exercise and diabetes mellitus • A. Coronary Artery Disease (CAD) or Coronary Heart Disease (CHD) • 1. Inadequate blood supply to heart muscle • 2. Can lead to angina, ischemia and infarctions
B. Myocardial Infarction (heart attack)-MI • 1. Ischemia (lack of blood) destroys muscle • 2. Treatments:nitroglycerin (vasodilator), angioplasty, bypass surgery, lasers(?)
C. Fibrillation-problem with SA node • 1. Atrial fibrillation- atria quiver and do not contract normally • 2. Ventricular fibrillation-death
D. Heart Murmurs and valve defects • 1. Murmur- blood leaks through valves • a. can be congenital • 2. Stenosis- valves become calcified, rough and narrow and do not close properly