2. The Cardiovascular System

3. Learning Outcome  Show an understanding of the cardiovascular system Describe the structure and function of the heart Describe the major components of the circulatory system

4. Cardiovascular System  Consists of Heart, Lungs and Vessels BODYHEARTLUNGS Systemic circulationPulmonary Circulation

5. The Heart  Made of cardiac muscle (myocardium)  Has it’s own blood supply  Two upper thin walled chambers – atria  Two lower thick walled chambers – ventricles  Atria collect blood from the body – attached to veins  Ventricles send blood to the body – attached to arteries

6. The Heart  Right side – deoxygenated  Left side – oxygenated  Separated by a thick walled septum  Right atrium and ventricle connected by tricuspid valve  Left atrium and ventricle connected by bicuspid (mitral) valve  Cuspid valves held shut by Chordae Tendinae  Left ventricle is thicker than the right

7. Vessels of the Heart  Pulmonary artery*  Pulmonary vein  Superior and Inferior Vena cava  Aorta* *Semi-lunar valves

8. Diagram of the Heart

9. Blood Flow Through the Heart 1.Vena Cava – Superior/Inferior 2.Right Atrium 3.Tricuspid Valve 4.Right ventricle 5.Pulmonary Artery LUNGS

10. Blood Flow Through the Heart 6.Pulmonary veins 7.Left Atrium 8.Bicuspid/Mitral/Atrioventricular valve 9.Left Ventricle 10.Aorta MAJOR ORGANS

11. Control of the Heart  Myogenic-Initiated from inside the heart as opposed to nervous stimulus outside  Initial Stimulus originates in the Sinoatrial node (SA node) *show location  Pacemaker determines heart rate  Wave of excitation across both atria causes them to contract

12. Control of the Heart  Sinoventricular node (SV node)  Sends waves of excitation along Purkinje Fibres which collectively make up the Bundle of Hiss. Along septum, radiate upwards  Ventricles contract  Both atria and both ventricles contract at the same time  Systole-contraction of heart  Diastole-Relaxation/filling of the heart

13. Diagram  On Board

14. Vessels of the Cardiovascular System  Arteries – Arterioles – Capillaries - Venules - Veins  Different structures and functions

15. Arteries  Carry blood Away from the heart, generally oxygenated there are some exceptions.  Blood in arteries in under high pressure  Their structure is related to their function  Round in structure with relatively thick walls composed of three layers

16. Arteries A.Tunica Intima – Single layer of endothelial cells B.Tunica Media – A thick layer containing elastic fibres and muscle tissues. Closer to heart more elastic fibres those further away have more muscle fibre C.Tunica Externa – Contains collagen fibres for strength

17. Diagram of an Artery

18. Veins  Carry blood back to the heart (generally deoxygenated)  Blood now flowing slowly, smoothly and under low pressure (structure related to this function)  Walls are relatively thin compared with arteries  Still same three layers but the tunica media differs in size – relatively narrow with few muscle fibres and elastic fibres  Semi Lunar valves present along length

19. Diagram of Veins

20. Capillaries  Link the arterial and venous blood supplies  Blood flow is slow, blood pressure is falling and is non-pulsatile  Capillaries form vast networks in all tissues and organs  Composed of only the Tunica Intima, only a single layer of endothelial cells, no elastic fibres and no muscle tissue

21. Capillaries  Exchange of materials between the blood and the body takes place in the capillary bed  Diagram of a capillary bed.

22. Diagram of a Capillary