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Cardiovascular System. Heart. The Pump. The heart is a pump with two sides Right side pumps blood to the lungs Pulmonary Left side pumps blood to the body systems Systemic Heart has four chambers Right and Left atria (receiving) Right and Left ventricles (pumps). Where is the heart?.
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Cardiovascular System Heart
The Pump • The heart is a pump with two sides • Right side pumps blood to the lungs • Pulmonary • Left side pumps blood to the body systems • Systemic • Heart has four chambers • Right and Left atria (receiving) • Right and Left ventricles (pumps)
Where is the heart? • The heart is located in the ventral body cavity in the PERICARDIAL CAVITY • The pericardial cavity is located in the mediastinum • The pericardial cavity is lined by a serous membrane called the pericardium • Pericardium has two divisions • Visceral pericardium – lies on surface of heart • Parietal pericardium – lies on the surface of the pericardium
Structure of Heart Wall • Three layers: • Epicardium: visceral pericardium, outer surface of the heart • Myocardium: cardiac muscle • Endocardium: inner surface of the heart. Covered by simple squamous epithelium the ENDOTHELIUM
Inside the heartPulmonary circuit • Right ATRIUM receives blood from superior and inferior VENA CAVA • Blood flows out of the R atrium into the Right VENTRICLE through the TRICUSPID VALVE • R ventricle contracts and blood flows out of the R ventricle through the PULMONARY SEMILUNAR VALVE into the PULMONARY TRUNK • Pulmonary trunk divides into the right and left PULMONARY ARTERIES and blood flows to the lungs
Inside the HeartSystemic circuit • Blood flows back into the L ATRIUM from the PULMONARY VEINS • Blood flows from the L atrium into the L VENTRICLE through the BICUSPID VALVE • The L ventricle contracts and blood flows out through the AORTIC SEMILUNAR VALVE into the AORTA and from the aorta to all parts of the body
Heart Strings? • Chordae tendineae • Strings that attach to the flaps (cusps) of the bicuspid and tricuspid valves from the papillary muscles • These “strings” limit the movements of the cusps and prevent backflow of blood into the artia
Coronary Circulation • Blood supply to the heart muscle • Consists of coronary arteries and coronary veins • Right and left coronary arteries arise from the base of the aorta • Highest blood pressure in the systemic circuit
Coronary Arteries • Right coronary artery • Marginal artery • Posterior interventricular artery • Left coronary artery • Circumflex artery • Anterior interventricular artery
Coronary Veins • Great cardiac vein • Middle cardiac vein • Posterior cardiac vein • Small cardiac vein • All empty into the CORONARY SINUS which empties into the right atrium
Electrical Conduction in the Heart • Cardiac muscle tissue contracts on its own • Special cells in the heart called NODAL CELLS are responsible for establishing the rate of cardiac contraction • SINOATRIAL NODE (SA node) in the right atrium is the cardiac pacemaker • Cells of the SA node generate 80-100 action potentials per minute • These potentials stimulate cells of the ATRIOVENTRICULAR NODE (AV node) to spread the signal for contraction to other parts of the heart.
Cardiac Output • Measure of the volume of blood pumped by the heart in a given period of time. • CO = heart rate X stroke volume • CO = 72 beats/min X 70ml/beat • CO = 5040 ml/min or ~5L/min • Average total blood volume is about 5L • This means that at rest one side of the heart pumps all the blood in the body through it in one minute • During exercise the cardiac output can increase to 30-50L/min!
Sheep heart 1. right atrium 2. right ventricle 3. left atrium 4. left ventricle 5. rigt/left auricles 6. precava 7. postcava 8. pulmonary trunk 9. aorta 10. pulmonary veins 11. innominate or brachiocephalic artery 12. left sublclavian artery 13. ligamentum arteriosum 14. coronary arteries 15. apex 16. interventricular septum 17. bicuspid valve 18. chordae tendineae 19. papillary muscles 20. trabeculae carnae 21. aortic semilunar valve Sheep Heart Key to the sheep heart