The document discusses the structure and function of the cardiac muscle and heart. It describes the heart chambers, valves, and blood flow through the heart. It explains that the heart pumps blood through contraction and relaxation in a cardiac cycle. It details the conducting system of the heart which generates and spreads the electrical impulse for heart contraction. This includes the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers. It notes that cardiac muscle cells are striated like skeletal muscle but have specialized ion channels and gap junctions allowing rapid impulse transmission.

1. Cardiac Muscle Dr. Mohammed Abdul Hannan Hazari Assistant Professor, Department of Physiology, Deccan College of Medical Sciences, Hyderabad

2. Heart

3. Coronary Arteries Anterior View Posterior View

4. Heart Location In The Chest Precordium

5. Weight: 300g Work: 72beats/min Pumps: 70mL/beat The busy and hard working heart! Heart

6. Heart Chambers Left atrium Right atrium Left ventricle Right ventricle

7. Heart Pump The heart pumps blood by contraction and relaxation. Contraction is called systole . Relaxation is called diastole . The Cardiac Cycle is the cycle through one systole and one diastole.

8. Heart Pump 2. Left Heart receives oxygenated blood from pulmonary veins pumps blood into systemic circulation 1. Right Heart receives venous blood from systemic circulation via superior and inferior vena cava into right atrium pumps blood to pulmonary circulation from right ventricle

9. Direction Of Flow In The Heart

10. Heart Valves 1. Atrioventricular Tricuspid between RA and RV three leaflets Mitral between LA and LV two leaflets 2. Semilunar Pulmonic --three leaflets Aortic --three leaflets

11. Cardiac Muscle Myocardial cells Working myocardial cells Contraction & relaxation (Heart Pump) Pacemaker cells Impulse generation & conduction (Conducting system of the heart)

12. Cardiac Muscle Striated Sarcomere is the functional unit. Nuclei - centrally located. Abundant mitochondria .

13. Cardiac Muscle SR is less abundant than in skeletal muscle. Sarcolemma has specialized ion channels that skeletal muscle does not  voltage-gated Ca 2+ channels.

14. The Sarcomere 1.6 – 1.7 μ

15. Cardiac Muscle

16. Functional Syncitium Fibers are branched; connect to one another at intercalated discs . The discs contain several gap junctions providing cytoplasmic continuity. Rapid transmission of impulse. 2 syncitia Atrial syncitium Ventricular syncitium *Separated by fibrous ring

17. Ventricular Action Potential

19. Conducting System Of The Heart

20. Direction Of Spread Of Impulse Sinoatrial node (SAN) – pacemaker Internodal pathways –fast conduction Atrioventricular node (AVN) – nodal delay Bundle of His – fast conduction Rt. & Left bundle branches Purkinje’s fibers Atrial muscle Ventricular muscle

21. Membrane Potential Of SAN L-type T-type

22. Conduction Speeds In Cardiac Tissue 1 Ventricular muscle 4 Purkinje system 1 Bundle of His 0.05 AV node 1 Atrial pathways 0.05 SA node Conduction Rate (mts/s) Tissue

23. Questions?

24. Thank You