Cardiovascular system

1. Cardiovascular system

2. Learning objectives I • To outline the cardiovascular system; • To state the general properties of cardiac muscle; • To describe the conducting system of the heart; • To describe the cardiac action potentials;

3. Learning objectives II • To describe cardiac cycle; • To define cardiac output and blood pressure; • To describe the structure of blood vessels; • To identify the control of cardiac function and blood circulation; • To state the composition of blood; • To describe the relation between blood and lymph.

4. Transport in Human The necessity: • far distance • high metabolic rate • slow diffusion • small surface area for material exchange

5. The circulatory system in Human • Transport medium: blood • Pumping device: heart • One- way flow: valves • Way for the exchange of materials: capillary network

6. Plasma ~ pale yellow, alkaline, 90% water, 10% solid materials • Plasma protein: fibrinogen, globulin, prothrombin & albumen • Carbohydrates & fats • Inorganic ions : Fe, Ca, K, Mg & Na • Nitrogen: urea, uric acid • Others: O2. CO2 & antitoxins

7. Erythrocytes(Red blood cell) • 5,000,000 RBC /mm3 • Female has less RBC than male • No nucleus in matured RBC • Tiny biconcave disc • Million hemoglobin/ RBC • Production: Fetus  liver; Adult  bone marrow • Life span: 4 months • Destruction: liver, spleen & bone marrow

9. Leukocytes(White blood cell) Colorless or transparent Amoeboid in shape 1-2, or more distinct nuclei 5000- 10000 WBC/ mm3 5 main classes of leukocytes: Neutrophils, eosinophils, basophils, monocytes & lymphocytes

11. Platelets • 250,000 blood platelets / mm3 • Small colorless fragments • No nucleus • Produced in bone marrow • Life span: 10 days

12. Function of platelets • Stimulate contraction of injured vessels  prevent blood loss • Adhere to one another plug the wound • Formation of thromboplastin main step of blood clotting Hemophilia ~ / plateletexcessive bleeding Hemorrhage ~ vit. K bleeding

13. Function of blood • Transportation ~ gas, food, wastes, heat, hormones & metabolites • Homeostasis ~ water balance, acid- base balance • Defense ~ blood clotting, phagocytosis & immune response

14. Structure of heart • Pericardium ~ double-layer sac surrounding the heart; ~ fluid fills the sac to reduce friction. • Heart chambers ~ right atrium ~ right ventricle ~ left atrium ~ left ventricle

17. Atrium • Upper chambers • Thin wall • Smaller than the ventricles • Receive blood from the veins • Push blood into ventricles

18. Ventricles • Lower chambers • Thicker muscle wall • Pump blood out of the heart to he lungs or around the whole body. • The muscular wall of the left ventricle is thicker than that of the right ventricle

19. Heart valves • Allow one-way flow of the blood. • Closure of the heart valves results in heart beat sound “Lup dup” • Tricuspid valve: between RA & RV • Biscuspid valve: between LA & LV • Semi-lunar valve: at the base of pulmonary artery & the aorta

20. Coronary system • Coronary artery ~ branches from aorta ~ supplies oxygen and nutrients to the heart muscle • Coronary vein ~ drains deoxygenated blood from the cardiac muscle into RA

21. Heart beat • Heart beats automatically i.e. it does not depend on impulses from the nervous system. • Contraction is generated within the muscle itself. • Pacemaker (SA node) is the origin of stimulus(cardiac action potential) for heart muscle contraction.

22. Important ! SA node initiates the heart beat, but the rate at which it beats can be varied by stimulation from the nervous system.

24. Spread of cardiac impulses SA node  Atrial muscle  AV node  Bundle of His  All parts of ventricle

25. Characteristics of cardiac muscle • Long refractive period ~ avoid fatigue • No tetanus or oxygen debt ~ avoid fatigue • Highly vascularized ~ adequate nutrients & oxygen

26. Characteristics of cardiac cycle • Pressure in Left ventricle > Pressure in Right ventricle thicker muscle wall of left ventricle • Length of cardiac cycle is varied at different state, but during exercise, less time is consumed.

27. Cardiac cycle • Sequence of events taking place in one heartbeat: ~ Atrial systole (contraction of atrium) ~ Ventricular systole (contraction of ventricles) ~ Diastole ( both atrium and ventricles relax)

29. Heart sound • 1st heart sound “Lup”: ~ closure of tricuspid & bicuspid valves ~ low pitched, not very loud, long duration • 2nd hear sound “Dup” ~ closure of semi-luna valves ~ high pitches, louder, short duration

30. Control of heart beat I • Cardiac pacemaker ( SA node) ~ nerve innervated the heart only regulate the rate of heart beat but not initiation of heart beat • Cardiac output ~ CO = Heart Rate x Stroke Volume

31. Control of heart beat II • Nervous regulation ~ Parasympathetic nerve Cardio-inhibitor center  vagus nerve  acetycholine  SA node  slow down heart beat ~ Sympathetic nerve Cardio-accelerator center  accelerator nerve  noradrenaline SA node   heart beat

32. Control of heart beat III • Hormonal control ~ Adrenaline   heart beat • Others ~  pH   Heart beat ~  temperature   Heart beat

33. Blood vessels • Artery ~ elastic artery ~ muscular artery ~ arterioles • Vein ~venules • Capillary

36. Artery • Thick muscular wall • Small lumen • Much elastic tissue • Blood under high pressure • Oxygenated blood except in pulmonary artery • Elastic artery, muscular artery, arterioles

37. Capillary • No muscle & elastic tissue • Links arteries to vein • Blood change from oxygenated to deoxygenated

38. Vein • Thin muscular wall • Little elastic tissue • Large lumen • Presence of valves • Deoxygenated except in pulmonary vein • Blood under low pressure

39. Blood flow in arteries Left ventricle contract  Push blood through aorta  Ventricles relax & semi- lunar valve close  Elastic aorta recoils  Muscular wall contracts & push blood to adjacent part of aorta

40. Blood flow in veins • Contraction of skeletal muscle ~ many veins are lying between large skeletal muscle; ~ muscles contract and squeeze the blood to flow forward in the vein.

42. Blood flow in veins II. Inspiration movement Inspiration  ICM & diaphragm contract  Enlarge thoracic cavity & pressure  -ve pressure suck blood towards the heart

43. Blood flow in veins III. Remaining blood pressure ~ blood pressure in the vein is not zero; ~ the remaining blood pressure pushes blood back to the heart.

44. Material exchange  Matter out: O2, glucose, amino acid, fatty acid, hormones, water & inorganic ions  Matter in: CO2, ammonia, lactic acids

45. Variation in blood pressure Blood pressure in Arteries> Arterioles> Venules & vein > capillaries

46. Variation on permeability of blood vessels Permeability of Capillaries > arteries, arterioles, venules & veins

47. Variation in total sectional area • Capillaries have the largest total section area. • This makes sure the blood staying in the tissue area longer, so promote material exchange.

48. Variation in velocity Velocity in arteries > veins > capillaries

49. Blood circulation in the body • Mammalian double circulation • Coronary circulation • Portal circulation • Renal system