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Lab and Lecture Notes. Location  Thoracic cavity between two lungs  ~2/3 to left of midline  surrounded by pericardium:  Fibrous pericardium- 

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Presentation on theme: "Lab and Lecture Notes. Location  Thoracic cavity between two lungs  ~2/3 to left of midline  surrounded by pericardium:  Fibrous pericardium- "— Presentation transcript:

1 Lab and Lecture Notes

2

3 Location  Thoracic cavity between two lungs  ~2/3 to left of midline  surrounded by pericardium:  Fibrous pericardium-  Inelastic and anchors heart in place  Inside is serous pericardium- double layer around heart  Parietal layer fused to fibrous pericardium  Inner visceral layer adheres tightly to heart  Filled with pericardial fluid- reduces friction during beat.

4 Figure 15.1

5 Heart Wall  Epicardium- outer layer  Myocardium- cardiac muscle  Two separate networks via gap junctions in intercalated discs- atrial & ventricular  Networks- contract as a unit  Endocardium- Squamous epithelium  lines inside of myocardium

6 Figure 15.2a

7 Figure 15.2b

8 Figure 15.2c

9 Chambers  4 chambers  2 upper chambers= Atria  Between is interatrial septum  Contains fossa ovalis- remnant of foramen ovalis  2 lower chambers = ventricles  Between is interventricular septum  Wall thickness depends on work load  Atria thinnest  Right ventricle pumps to lungs & thinner than left

10 Great Vessels Of Heart- Right  Superior & inferior Vena Cavae  Delivers deoxygenated blood to R. atrium from body  Coronary sinus drains heart muscle veins  R. Atrium  Tricuspid Valve  R. Ventricle  pumps through Pulmonary Trunk   R & L pulmonary arteries   lungs

11 Great Vessels Of Heart-Left  Pulmonary Veins from lungs  oxygenated blood   L. atrium  Bicusid (Mitral) Valve  Left ventricle   ascending aorta  body  Between pulmonary trunk & aortic arch is ligamentum arteriosum  fetal ductus arteriosum remnant

12 Figure 15.3a

13 Figure 15.3b

14 Figure 15.3c

15 Valves  Designed to prevent back flow in response to pressure changes  Atrioventricular (AV) valves  Between atria and ventricles  Right = tricuspid valve (3 cusps)  Left = bicuspid or mitral valve  Semilunar valves near origin of aorta & pulmonary trunk  Aortic & pulmonary valves respectively

16 Figure 15.4ab

17 Figure 15.4c

18 Figure 15.4d

19 Figure 15.5a

20 Figure 15.5b

21 Blood Supply Of Heart  Blood flow through vessels in myocardium = coronary circulation  L. & Right coronary arteries  branch from aorta  branch to carry blood throughout muscle  Deoxygenated blood collected by Coronary Sinus (posterior)  Empties into R. Atrium

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23 Conduction System  1% of cardiac muscle generate action potentials= Pacemaker & Conduction system  Normally begins at sinoatrial (SA) node   Atria & atria contract   AV node -slows   AV bundle (Bundle of His)   bundle branches  Purkinje fibers   apex and up- then ventricles contract

24 Pacemaker  Depolarize spontaneously  sinoatrial node ~100times /min  also AV node ~40-60 times/min  in ventricle ~20-35 /min  Fastest one run runs the heart = pacemaker  Normally the sinoatrial node

25 Figure 15.6

26 Electrocardiogram  Recording of currents from cardiac conduction on skin = electrocardiogram (EKG or ECG)  P wave= atrial depolarization  Contraction begins right after peak  Repolarization is masked in QRS  QRS complex= Ventricular depolarization  Contraction of ventricle  T-wave = ventricular repolarization  Just after ventricles relax

27 Figure 15.7

28 Cardiac Cycle  after T-wave  ventricular diastole  Ventricular pressure drops below atrial & AV valves open  ventricular filling occurs  After P-wave  atrial systole  Finishes filling ventricle (`25%)  After QRS  ventricular systole  Pressure pushes AV valves closed  Pushes semilunar valves open and ejection occurs  Ejection until ventricle relaxes enough for arterial pressure to close semilunar valves

29 Action Potential  Review muscle  Heart has addition of External Ca 2+  creates a plateau  prolonged depolarized period.  Can not go into tetanus.

30 Figure 15.8

31 Flow Terms  Cardiac Output (CO) = liters/min pumped  Heart Rate (HR) = beats/minute (bpm)  Stroke volume (SV) = volume/beat  CO = HR x SV

32 Controls- Stroke Volume (S.V.)  Degree of stretch = Frank-Starling law  Increase diastolic Volume increases strength of contraction  increased S.V.  Increased venous return  increased S.V.  increased sympathetic activity  High back pressure in artery  decreased S.V.  Slows semilunar valve opening

33 Controls- Heart Rate  Pacemaker adjusted by nerves  Cardiovascular center in Medulla  parasympathetic- ACh slows  Via vagus nerve  Sympathetic - norepinephrine speeds  Sensory input for control:  baroreceptors (aortic arch & carotid sinus)- B.P.  Chemoreceptors- O 2, CO 2, pH

34 Other Controls  Hormones:  Epinephrine & norepinephrine increase H.R.  Thyroid hormones stimulate H.R.  Called tachycardia  Ions  Increased Na + or K + decrease H.R. & contraction force  Increased Ca 2+ increases H.R. & contraction force

35 Figure 15.9

36 Exercise  Aerobic exercise (longer than 20 min) strengthens cardiovascular system  Well trained athlete  doubles maximum C.O.  Resting C.O. about the same but resting H.R. decreased

37 Figure 15.10


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