1. 1 The Heart The Cardiovascular System What are the components? (See an anatomy book and chapter 9 of G&H)

2. 2 Functions of the Heart Blood vessels Arteries- away from heart Veins- toward heart Pulmonary circuit- blood to lungs Systemic – blood to organs of the body Includes heart and lung wall tissues

3. 3 Location Base- inferior border of second rib Apex- rests on diaphragm and in between 5 th and 6 th rib Tilts to the left and anteriorly

4. 4 Pericardial Membranes (3 total) and Heart wall Fibrous skeleton- anchoring, structural support, and electrical insulation

5. 5

6. 6

7. 7 Atria Right: Auricle Smooth wall (posterior) Pectinate muscles Crista terminalis Fossa ovalis Coronary sinus, IVC, SVC openings Right AV valve Left: Mostly smooth with pectinate muscle Left AV valve What vessels lead into each atria? Describe the blood these vessels are carrying

8. 8 ventricles Trabeculae Carneae Papillary muscles Chordae tendineae Valves

9. 9

10. 10 Valves

11. 11 Sulci and Vessels Coronary sulcus Interventricular sulci (anterior and posterior) Cardiac vessels Arteries veins

12. 12 Blood Flow Pulmonary vs systemic circuit

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14. 14

15. 15 “Lub-Dub” Sounds

16. 16 Conductive System of the Heart-Myogenic (72bpm) Muscle, not Nerves that are autorhythmic! Sinoatrial node- pacemaker Internodal bundles Atrioventricular node Atrioventricular bundles (bundle of His) Bundle branches Purkinje fibers

17. 17 Innervation by Autonomic Nervous System Alter rate and Force only! Visceral sensory Parasympathetic- (Vagus)- slow down (20bpm or even stop)- SA would normally beat at 100bpm- but vagal tone slows down. Sympathetic – speed up (230bpm) Hypothalamus and Amygdala and Medulla Oblongata Most dense at SA and AV node

18. 18 Review of Heart Muscle Cardiocytes Branch Intercalated discs- interdigitating folds, mechanical junctions (desmosomes) and electrical junctions (gap junctions).

19. 19 Fetal Circulation Foramen ovale- right to left shunt. Most of the blood goes through here. Ductus arteriosus- right to left shunt.

20. 20 Blood Flow within the Fetal Heart Right atrium Foramen ovale Left ventricle Left atrium Systemic circuit Aorta Right ventricle Pulmonary trunk Ductus arteriosus Pulmonary circuit (Most of the blood)

21. 21 Birth Prostaglandin levels drop Baby breathes- lowers pressure in pulmonary circuit Umbilical cord is clamped and cut and increases systemic pressure Foramen ovale closes and becomes fossa ovalis Ductus arteriosus closes and becomes ligamentum arteriosum (oxygen content is signal for vessel to close)

22. 22 Foramen Ovale Fossa Ovalis

23. 23 Ligamentum Arteriosum Ductus Arteriosus

24. 24 PDA- patent ductus arteriosus Left to right shunt Blood flows back to lungs repeatedly- why? Net CO decreases so blood vol. increase and CO goes back toward normal Left and right ventricular hypertrophy Characteristic cyanosis of baby Pulmonary veins aorta Pulmonary trunk IVC

25. 25 Tetralogy of Fallot “Blue Babies” Right to left shunt Tetralogy of Fallot is made up of 4 heart defects

26. 26 Physiologic considerations Electrical features to know Cardiac muscle fibers: branched, with intercalated disks. Gap junctions. Low resistance (1/400) pathway for electrical spread from cell to cell. “functional syncitium” Two types of fibers in the heart: “specialized” (or leading cells and “contractile” (or following cells.) Autorhythmicity; intrinsic to the specialized cells. AP is generated within these cells (membrane feature) not from nerves or hormones. “intrinsic rhythm” Nerves, hormones can modify rate or force.

27. 27 Physiologic considerations Mechanical (contraction) features to know: 4 chambers, septa, valves Non-conductive connective tissue skeleton, wringing action. In ventricles direction is propelling blood from apex toward base. Systole = period of contraction and emptying Diastole = period of relaxation and filling Specify which chamber, as atrial and ventricular events are not the same. Show this! Ohm’s law: Pressure difference = flow x resistance Pressures generated in rt and left sides are different (more later.) Valves: damage can lead to stenosis and/or regurgitation

28. 28 Physiologic considerations Vasculature: Normal circuit is A,a,c,v,V Arteries: thick wall, narrower lumen than veins of same outer diameter. Muscular and elastic. Stretch and recoil, give back potential for kinetic energy. Arterioles: resistance vessels; precapillary sphincters. Capillaries: exchange vessels, thin wall, simple squamous endothelium, diffusion. Venules: thin walled, more elastic Veins: Capacitance vessels, hold large volume of blood supply

29. 29 Physiologic considerations Right/left side differences: In series circuit, R to L and around again. Same amt of blood pushed by each side, “cardiac output.” CO=6L/min at rest. R side (pulmonary circuit) pushes blood to lungs; low resistance circuit L side (systemic circuit) pushes blood to all organs in head, torso and limbs, ie. The system; high resistance circuit. In summary, same amt of blood, but with different resistance, require different pressures. MAP on L side = 100 mm Hg; MAP on R side =10 mm Hg

30. 30 Series Circuit