1 The Heart

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4 The Heart Heart pumps over 1 million gallons per yearOver 60,000 miles of blood vessels

5 I. Layers of Heart Wall Pericardium Myocardium Endocardiumprotects and anchors the heart, prevents overstretching Myocardium cardiac muscle layer is the bulk of the heart Endocardium chamber lining & valves

6 II. Structures of the HeartLeft common carrotid Left subclavian artery Brachiocephalic trunk aorta left pulmonary artery Superior vena cava Mitral/bicuspid Right atrium pulmonary semi-lunar Left atrium Right pulmonary vein Aortic semi-lunar tricuspid Chordae tendinae myocardium Papillary muscle Left ventricle inferior vena cava Interventricular septum Right ventricle Descending aorta

7 III. Blood Circulation Two closed circuits, the systemic and pulmonicPulmonary circulation Right atrium pumps blood through the tricuspid valve to the right ventricle Right ventricle pumps blood through the pulmonary semi-lunar valve to pulmonary trunk pulmonary trunk branches into left and right pulmonary arteries Pulmonary arteries carry blood to lungs for exchange of gases Which gases and in what direction? Oxygenated blood returns to the heart through the pulmonary veins into the left ventricle

8 Blood Circulation (con’t)Systemic circulation Left atrium pumps blood though the mitral valve (bicuspid) to the left ventricle Why is this valve replaced the most often? left ventricle pumps oxygenated blood through the aortic semi-lunar valve into aorta Why is the myocardium of this chamber the thickest? Aorta branches into many arteries that travel to organs Arteries branch into many arterioles in tissue. Arterioles branch into thin-walled capillaries for exchange of gases and nutrients Deoxygenated blood begins its return in venules Venules merge into veins and return to right atrium via the vena cavas

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12 IV. Blood Flow Off Descending AortaCommon carotid artery (left) First branch coming off of the aorta and it carries blood to head and brain Returns through jugular veins to superior vena cava Left & right Subclavian arteries carries blood to the arms and the subclavian veins return blood to the superior vena cava.

13 Blood flow off Descending Aorta (2)Celiac artery carries blood to stomach, spleen and liver Portal vein leads to the liver and leaves through the hepatic (liver) vein to inferior vena cava. Superior mesenteric artery carries blood to the small intestine, which in turn connects to the portal vein. This way all materials entering the blood stream from the digestive tract are sent directly to the liver for detoxification.

14 Blood flow off Descending Aorta (3)Inferior mesenteric artery leads to large intestine (and small, but mostly large) Large intestine leads to internal iliac vein (hypogastric) that connects to the inferior vena cava The Iliac arteries branches to supply blood to reproductive and excretory organs, as well as the legs Blood returns through iliac veins to inferior vena cava

15 HEART QUESTIONS How many times will your heart beat in 80 years?How much blood is pumped with each heart beat?

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17 V. Cardiac Cycle Atrial diastole Atrial systoleboth atria fill with blood atrioventricular valves are open and the semilunar valves are closed 75% of ventricular filling occurs now lasts about 0.7 seconds Atrial systole atria contract forcing the remaining 25% of the blood into the ventricles lasts about 0.1 seconds

18 Cardiac Cycle (2) Ventricular diastole Ventricular systoleventricles are relaxing lasts about 0.5 seconds Ventricular systole ventricles are contracting blood is being forced into the aorta and pulmonary arteries. the semilunar valves are open and the atrioventricular valves are closed. lasts about 0.3 seconds

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20 VI. Cardiac Conduction SystemImpulse originates in sinoatrial node (SA node or pacemaker) which is located in the superior region of the right atrium. Impulse spreads across both atria which causes them to contract at the same time. The impulse reaches atrioventricular node (AV node) located at the top of the right ventricle.

21 Cardiac Conduction System (con’t)From the AV node the impulse passes through the atrioventricular bundle node to (Bundle of His). The Bundle of His branches off into right and left bundle branches. The impulse now flows through the many branches of the Purkinje fibers which pass deep into the ventricular myocardium.

22 Pacemaker Bundle of His AV node Purkinje fibers

23 VII. Electrocardiogram-ECG or EKGAction potentials of all active cells can be detected and recorded The machine amplifies electrical impulses generated by your muscles. 4 basic parts to analyze: P wave P to Q interval QRS complex T wave

24 VIII. ECG Analysis Parameters Horizontal Axis Vertical AxisMeasures time of duration. Each box or mm = seconds Vertical Axis Measures voltage or amplitude Each box or mm = 0.1 mV

25 P-Wave Depolarization of the atria (atrial systole)Amplitude of P-Wave should be less than 0.2 mV to 0.3 mV Duration of P-Wave should be less than seconds

26 QRS Complex Atria repolarization (atrial diastole)Ventricle depolarization (ventricular systole) Amplitude should be greater than 0.5 mV in leads 1, 2, or 3 Measured from tip of R to bottom of S Duration should be less than secs.

27 T-Wave (isoelectric) Repolarization of ventricles (ventricular diastole) Amplitude should be less than 0.5 and greater than 1/10 of R wave for that segment. T-wave should be on the isoelectric line Duration not a concern T-wave should be in the same direction as the R- wave

28 P-Q Interval Measured from beginning of P to beginning of Q.Between 0.12 and 0.2 second duration. Too long indicates AV block.

29 ST Segment Amplitude should be isoelectricIf depressed more than 2 mm indicates ischemic heart. Most often caused by atherosclerosis. Duration should be between sec.

30 Heart Rate HR= 60/(R to R Interval in seconds)

31 Cardiac Cycle

32 Regulation of Heart Rate

33 I. Cardiac Output (CO) The amount of blood the heart pumps in 1 minute. stroke volume (SV) = amount of blood pumped per beat

34 II. Influences on Stroke VolumePreload (affect of stretching heart muscle) Frank-Starling Law of Heart The longer the filling time, the greater the stretch of cardiac muscle more muscle is stretched, greater force of contraction This explains why athletes have lower resting heart rates but the same cardiac output more blood more force of contraction results Contractility autonomic nerves, hormones, Ca+2 or K+ levels Afterload amount of pressure created by the blood in the way high blood pressure creates high afterload

35 III. Control Centers for Heart RateTwo centers found in the medulla Cardioacceleratory center has a sympathetic nerve (cardioaccelerator nerve) that connects to the SA node of the heart. Cardioinhibitory center has a parasympathetic nerve (vagus nerve) that connects to the SA node of the heart.

36 IV. Factors that effect heart rateBlood Pressure (BP) Carotid Sinus Reflex: As the BP in the carotid sinus rises the walls of the carotid sinuses stretch (baroreceptors) Stretching increases stimulation of the glossopharyngeal nerve, which leads to the cardioinhibitory center in the medulla. The inhibitory center stimulates the Vagus nerve which slows down the heart rate Therefore a drop in HR, produced a drop in CO, which produced a drop in blood pressure, that reduced the amount of stretch in the carotid sinus. What happens if there is a drop in blood pressure in the carotid sinus?

37 Factors that effect heart rate (con’t)Aortic reflex (regulates BP to rest of body) Right Atrial (Bainbridge) reflex There are baroreceptors located in the right atrium and in the superior and inferior vena cavas. When these are stimulated heart rate increases. Why increase heart rate instead of decrease?

38 Factors that effect heart rate (con’t)Chemical Factors CO2 increases heart rate Adrenaline (epinephrine) Ca 2+ Na+ and K+ lower heart rate

39 Factors that effect heart rate (con’t)Other factors Sex females have higher heart rates Age older-slower Exercise increase person who exercises regularly has a lower resting heart rate than one who doesn't - called Bradycardia Temperature Higher temperature, higher heart rate

40 Cardiovascular Disease (CVD)In the U.S.—1 million deaths/year

41 I. Coronary heart disease (56%)Cause Slow build up of fatty plaque (atherosclerosis) along the walls of the coronary blood vessels which reduces blood flow to heart The drop in O2 levels (ischemia) causes a angina which could lead to myocardial infarction.

42 B. Diagnosis Outward symptoms of a heart attack:pain in chest and left arm cyanosis of lips nausea dizziness shortness of breath cold sweat denial

43 Diagnosis (con’t) Exercise ECG ST Depression Problems with PR intervalAngiogram A catheter is inserted into femoral artery of pelvis and worked into the aorta. Then dye is injected through catheter. A fluoroscope will show the dye pathway. Any narrowing or blockages will show up on the fluoroscope.

44 C. Treatment Bypass surgeryremove a vein from the leg and use it to bypass a blockage in heart vessel stop heart and put on a heart lung machine Angioplasty (see angiogram) Catheter with specialized tip is positioned where the coronary artery is narrowed or blocked. Use syringe to blow up catheter’s balloon (fig , page 599). Balloon presses the plaque up against the walls of the vessel.

45 By-pass Graft

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47 Coronary Angioplasty

48 CVD Stroke 20% The interruption of blood flow to the brain Causesthrombus vs. embolus atherosclerosis (has no symptoms) aneurysm-broken blood vessel

49 Stent in an Artery Maintains patency of blood vessel

50 CVD Hypertension 7% Myocardial degeneration 5% Arteriosclerosis 4%Chronic high blood pressure More common in black males than white. Myocardial degeneration 5% Heart muscle degenerates Arteriosclerosis 4% Hardening of the arteries Rheumatic fever 2% Childhood disease that damages heart valves

51 Risk Factors associated with Cardiovascular Diseaseage sex genetics diets high in fat (hyperlipidemia) high blood pressure smoking stress alcohol obesity inactivity

52 First Heart Attack Risk TestAge: Men: 0 pts = Less than 35, 1 pt = 35 to39, 2 pts = 40 to 48, 3 pts = 49 to 53, 4 pts = 54+. Women: 0 pts = Less than 42, 1 pt = 43 to 45, 2 pts = 46 to 54, 3 pts = 55 to 73, 4 pts = 74+. Family History: 2 pts if family has a history (parents and/or grandparents) of heart disease or heart attack before age 60. Inactivity: 1 pt if you rarely exercise or do anything physically demanding. Weight: 1 pt if you are more than 20 pounds overweight.

53 First Heart Attack Risk Test (con’t)Inactivity: 1 pt if you rarely exercise or do anything physically demanding. Weight: 1 pt if you are more than 20 pounds overweight. Smoker: 1 pts if you smoke Diabetes: 1 pt if you are male, 2 pts if your are female. Total Cholesterol Level: 0 pts if you are less than 240 mg/dl, 1 pt if you are mg/dl and 2pts if you are greater than 315 mg/dl.

54 First Heart Attack Risk Test (con’t)HDL Level: 2 pts if you are under 30 mg/dl, 1 pt if you are mg/dl or 1 pt if you are over 60 mg/dl, and 0 pts if you are mg/dl. Blood Pressure (Systolic): 0 pts if less than 140 mmhg, 1 pt if mm/hg and 2 pts if greater than 170 mmhg. Scoring the test: Any value above four represents an above average risk; the higher the number, the greater the risk.

55 IX. Benefits of Aerobic ExerciseNormalizes BP Bradycardia heart pumps more blood per beat more efficient Increases the number of RBC's Increases caloric output Decreases LDL's and increases HDL's High density lipoproteins (HDL's) contain more protein than fat and HDL's are able to remove low density lipoproteins (LDL's) from the blood stream LDL's have a higher proportion of fat and tend to accumulate along the walls of the arteries of the body, and heart in cerebral arteries

56 X. Designing A Good Exercise ProgramCorrect intensity as measured by heart rate Heart must work athlete % of the max. HR normal % of the max. HR older 60-70% of the max. HR Maximum HR= 220 — age e.g. a normal person 40 years of age (220-40) x 70% 180 x 0.7 =126.0 beats/min x 0.8=144 beats/min.

57 Designing A Good Exercise Program (con’t)Correct duration 20 minutes or longer at target heart rate Frequency 3-4 times a week or every other day