Uploaded byKameshwaran Sugavanam
CARDIOVASCULAR SYSTEM - ANATOMY & PHYSIOLOGY
The cardiovascular system consists of the heart and blood vessels that circulate blood throughout the body. The heart has four chambers and uses valves to ensure one-way blood flow. It is regulated by the autonomic nervous system. During each cardiac cycle, the atria contract followed by ventricular contraction that pumps blood out of the heart into the arteries. Relaxation of the ventricles allows blood to flow back into the heart. The conductive system generates electrical signals that coordinate the heart's pumping action.
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CARDIOVASCULAR SYSTEM - ANATOMY & PHYSIOLOGY
- 1. Cardiovascular System ANATOMY &PHYSIOLOGY -By-DR.S.Kameshwaran
- 2. Cardiovascular System • Alsoknown as circulatory system • Consists of: the heart, arteries, veins, capillaries
- 3. Functions of thecardio vascular system: • Distribution of oxygen and nutrients to all the body parts • Transportation of CO2 and metabolic waste products from tissues to lungs and other excretory organs • Distribution of water electrolytes and hormones through out the body • Part of immune system • Thermoregulation
- 4. Heart • Blood pumpedthrough the muscular organ called heart • It is composed of strong cardiac muscle tissue • Shows rhythmic contraction and relaxation • Due to this blood pumped to the entire body along with nutrients and oxygen
- 5. ANATOMY OF HEART: •Heart is a muscular organ • Size is about closed fist • Average weight – female – 250-300gms, Male – 300-350gms • Average human heart beats 70-72 times per minute • Situated in the thoracic cavity – in the mediastinum space, just above the diaphragm • Present at the level of thoracic vertebrae T5-T8 • Present in the midline just tilted towards the left • It is a rounded cone shaped structure
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- 7. Walls of theHeart • Pericardium – loose fitting sac surrounding the heart • EPICARDIUM • MYOCARDIUM • ENDOCARDIUM
- 8. Epicardium: outer layerof heart Consist of 2 layers – Fibrous pericardium – tough, loose- fitting, inelastic – Serous pericardium • Parietal layer: lines the inside of the fibrous pericardium • Visceral layer: adheres to outside of the heart – Pericardial space: between parietal and visceral layer • Filled with 10-15mL of pericardial fluid • Decreases friction
- 10. Myocardium: • It isthe thickest layer • contractile layer composed of cardiac muscle cells • Cardiac muscle is striated, involuntary, and branched • Heart contracts by contraction of myocardial membrane Endocardium: • – inner most and third layer of heart wall – Consist thin layer of specialized epithelial tissue (Endothelium) – Covers inner layers of heart and provides smooth flow of blood inside the heart
- 11. Chambers of theHeart • Heart is a hollow chamber • Divided in to 4 different chambers Atria – two superior chambers – “Receiving chambers” – Thin walled low pressure chambers – Blood from superior vena cava & Inferior vena cava enters atria Ventricles – two inferior chambers – “pumping chambers” – Thick walled high pressure chamber – Thick muscular walls to increase force of pumping action – Left & right venticles Separated by interventricular septum
- 12. Valves of theHeart “Permit blood flow in one direction during circulation” • Atrioventricular valves (AV valves) – Also cuspid valves – Between atria and ventricles • Semilunar (SL valves) – Between R ventricle and pulmonary arteries and L ventricle and aorta
- 13. Atrioventricular Valves Tricuspid valve –Between R atrium and ventricle – 3 flaps of endocardium – Connected to ventricular papillary muscle via chordae tendinea Bicuspid valve – Between L atrium and ventricle – Also called mitral valve – Two flaps of endocardium – Connected to ventricular papillary muscle via chordae tendinea
- 15. Semilunar Valves • Pulmonarysemilunar valve – Btwn R ventricle and pulmonary trunk • Aorta semilunar valve – Btwn L ventricle and aorta
- 16. Chambers & Valves Tracethe blood flow through the heart
- 17. Blood Supply tothe Heart • To work efficiently the heart needs a continues blood supply • Needs to supply oxygen and nutrients and to remove the waste materials • Heart has its own system of circulation – coronary circulation • Left and right coronary arteries arises at the base of aorta • From there they supply the blood to right and left side of heart • Coronary artery provides – pure blood • Coronary vein – remove waste products • Coronary sinus – empties the deoxygenated blood in to the right atrium
- 19. CONDUCTION SYSTEM OFTHE HEART Conduction system of heart includes 6 components • SINOATRIL (SA) NODE • INTERNODAL PATHWAYS • ATRIOVENTRICULAAR (AV) NODE • BUNDLE OF HIS • BUNDLE BRANCHES • PURKINJIE FIBRES
- 21. • Sinoatrial Node(SA Node) – It is located it right atrium – near the opening of superior vena cava. – It is 1.5cm length & 0.5cm width – It is also known as Pacemaker of the heart – It comprises of pacemaker cells (P) & some myofilaments – Impulse is generated by the P cells and transmitted with in the conducting system for the excitation and contraction of heart muscles
- 22. INTERNODAL PATHWAYS: • Theyconnect SA node and AV node • They are – Anterior internodal pathway – Middle internodal pathway – Posterior internodal pathway
- 23. ATRIOVENTRICULAAR (AV) NODE •It is located in the lower part of the right atrium • Close to the interatrial septum • It is 2.2cm long 10mm wide and 3 mm thick • The pacemaker (P) cells are also present in the AV node • Impulse formation is slower in AV node than SA node
- 24. BUNDLE OF HIS: •A small fibre bundle arising from the AV node and terminating in the purkinje system - Bundle of His It is located beneath the AV node and passes towards the interventricular septum It is about 1 cm in length Left branch bundle & Right branch bundle In case of non functioning SA & AV node impulse generated by Bundle of His
- 26. BUNDLE BRANCHES: “The branchesof bundle fibres enters the walls of the ventricle to further branch out in to very small fibre bundles – further branch in to very small fibre“ – Purkinje fibres The bundle branches also have ability to generate impulses 2 types: Right bundle branch & Left Bundle branch
- 27. PURKINJE FIBRES: • Thefibres forms a network of small bundle of conducting fibres • They are located all over the sub endocardial regions of R&L ventricles
- 28. PATHWAY OF NERVEIMPULSE SA NODE ↓ INTERNODAL PATHWAY ↓ AV NODE ↓ BUNDLE OF HIS ↓ RIGHT AND LEFT BUNDLE BRANCHES ↓ PURKINJE FIBRES ↓ VENTRICULAR MYOCYTES
- 29. REGULATION OF HEARTBY ANS The centre for regulation of the heart is CARDIOVASCULAR CENTRE Which is present in the medulla oblongata It receives input from Sensory receptor Higher centre of brain The cardiac output is maintained either by increasing or decreasing the frequency of nerve impulses in the ANS – increase or decrease cardiac output.
- 30. • Sympathetic Neurons(thoracic region of spinal cord) – release - Nor-Epinephrine – acts on - muscle fiber of heart – produces 2 effects • Increases heart rate – by increasing the rate of spontaneous depolarization in SA node, AV Node & cardiac muscle fibers • Increases contractility – by increasing entry of Ca2+ ions through voltage gated calcium channels present in the contractile fibers • Maximum synthetic stimulation can be 200pulse per min
- 31. PARA SYMPATHETIC NEURONS: •Reaches heart via Xth cranial nerve (vagus) • Releases acetylcholine – act on muscle fibers of heart – decreases HR by decreasing the rate of spontaneous depolarization in cardiac muscle fibres • The heart can slow to 20-30 beats/Min
- 34. PHYSIOLOGY OF HEART: •The heart has four separate chambers. • The upper chamber on each side of the heart, which is called an atrium - receives and collects the blood coming to the heart. • The atrium then delivers blood to the powerful lower chamber, called a ventricle - which pumps blood away from the heart through powerful, rhythmic contractions.
- 35. • The humanheart doing two pumps in one. • The right side receives oxygen-poor blood from the various regions of the body and delivers it to the lungs. • In the lungs - oxygen is absorbed in the blood. • The left side of the heart receives the oxygen-rich blood from the lungs and delivers it to the rest of the body.
- 36. Cardiac cells • Cardiaccells are cylindrical in shape • It is arranged such if one cell is stimulated it stimulates the adjacent cell Two types of cardiac cells • Electrical cells & Myocardial cells Electrical cells - Specialized cell • This cell cannot able to contract but can conduct the nerve impulse • Electrical impulse – produced in SA Node – forwarded to rest of the heart – force of contraction is generated – pumps the blood.
- 37. ACTION POTENTIAL • Restingmembrane potential at the heart is – 90mV • Sudden influx of Na+ Ions in cardiac membrane – initiates action potential in myocardial cell - Phase 0/ Upstroke of action potential • outward movement of K+ ions – initial phase of repolarization – 1st phase of action potential
- 38. Increase inthe Inward movement of Ca2+ ions and outward movement of K+ ions - 2nd Phase/ plateau phase Inward movement of calcium ions (decreasing)& outward movement of potassium ions (increasing) - 3rd phase/ phase of repolarization The potassium ions concentration becomes equilibrium by the outward conduction of potassium ions in the third phase -4th Phase/ Phase of repolarization
- 41. CARDIAC CYCLE “Rhythmic Pumpingof Heart” Contraction and relaxation occurring during the one heart beat – cardiac cycle Phases of Cardiac Cycle 1. Systole – contraction 2. Diastole – relaxation • At a normal heart rate, one cardiac cycle last for 0.8 seconds!
- 42. • “One contraction(systole) and one relaxation (diastole) of auricles and ventricles resulting in one heart beat” » - known as CARDIAC CYCLE SYSTOLE: • A significant pumping of blood from the cardiac chamber DIASTOLE: • Significant entry of blood in to the cardiac chamber
- 43. Stages of cardiaccycle: 4 stages: • ATRIAL SYSTOLE • VENTRICULAR SYSTOLE • VENTRICULAR DIASTOLE • JOINT DIASTOLE ATRIAL SYSTOLE: This is marked by stimulation of SA node A wave of contraction spreads through atria and bicuspide and tricuspid valves open up Which pumps blood from atria in to ventricles
- 44. VENTRICULAR SYSTOLE: • Contractionof ventricles occurs as the wave of contraction spreads through both the ventricles • This is stimulated by AV node stimulation • The bi & tri cuspid valves close and produce the first heart sound – LUB • The sound lasting for 0.16-0.90 sec • As the ventricle contracts blood flows into dorsal aorta from left ventricle & pulmonary artery from right ventricle
- 45. VENTRICULAR DIASTOLE: • Asventricles relax both semilunar valves closes with a sound of – DUB • Pressure with in the ventricles decreases continuously • When the pressure falls below the pressure of atrium both bicuspid and tricuspid valves open and the blood again flows in to the ventricles
- 46. JOINT DIASTOLE: • Beforethe cycle starts again, both the atria and ventricles are relaxed - JOINT DIASTOLE During this state blood flows from superior and inferior vena cava into the atria & atria to ventricles Duration of cardiac cycle: 0.88 Sec Which can be divided as Auricular systole - 0.18 Sec Auricular diastole - 0.08 sec Ventricular systole - 0.30 sec Ventricular diastole - 0.32 sec
- 47. CARDIAC OUTPUT: “The amountof blood flowing from the heart ( from left ventricle in to aorta) in one heart beat” Cardiac output = stroke volume x Heart rate = 70ml x 72/min = 5040 ml/min = about 5 liters/ min Stroke volume = volume of blood pumped by heart per heart beat Heart rate = ventricular systole / min
- 48. PULSE: “A wave ofdistension felt in the arteries with each heartbeat “ It is counted from radial artery of the wrist Pulse rate normally is the same as the heart rate Tachycardia – increase in the pulse/ heart rate over 100 beats/min Bradycardia – decrease in the heart/pulse rate under 50 beats/ min Normal pulse rate – 70-90 per minute Men – 72/min, women – 80/min
- 49. ELECTRO CARDIOGRAM(ECG) Electrical current generated in the heart by the propagation of action potential can be detected on the surface of the body as electrical signals These changing signals are recorded by an instrument – Electrocardigram (ECG) ECG – composite record of action potentials produced by the heart muscles Recording done by using electrodes – helps in detection of cardiac abnormalities
- 51. There are 3recognizable waves – P wave – QRS complex – T wave P WAVE: This is first wave spreading from SA node through contractile fibres in both atria Representing atrial depolarisation It is seen as a small upward deflection on ECG
- 52. QRS COMPLEX • thisis the second wave • Occurs due to action potential spreadds through ventricular contractile fibres • Representing rapid ventricular depolarisation • It continues as large upright, triangular wave • Beginning as downward deflection and ending as downward wave
- 53. T WAVE: • Thisis the third wave • Its seen when ventricle relax • Indicating ventricular repolarisation • Appear as dome shaped upward deflection • Smaller and wider than QRS complex • This is due to the slower repolarisation than the depolarisation
- 54. • Size ofeach wave appearing on ECG helps in interpreting any abnormality • Larger P wave – Enlarged atrium • Large Q wave – possible myocardial infarction • Large R wave – Enlargement of ventricles • Flatter T wave – insufficient O2 supply to cardiac muscles • Elevated T wave – high level of K+ in the blood
- 55. Analysis of ECG: •Intervals or segments are the time spans present between the waves • This helps in analyzing an ECG • P-Q INTERVAL • S-T SEGMENT • Q-T INTERVALS
- 56. BLOOD PRESSURE “BLOOD PRESSURE(BP) IS THE PRESSURE OF CIRCULATING BLOOD ON THE WALLS OF BLOOD VESSELS” Normal blood pressure has high systolic value and low diastole value 120mm Hg/ 80mm Hg in arteries The blood pressure is measured by sphygmomanometer
- 57. Types of bloodpressure: Arterial blood pressure may be of 4 types Systolic pressure : maximum pressure exerted during systole of the heart when LV contact & pump blood to aorta), Normal value: 120mm Hg Occurs in the beginning of the cardiac cycle Diastolic pressure: it is the minimum pressure on the arteries Normal value: 90mm Hg It occurs at the end of the cardiac cycle When V is in resting phase after pumping blood Pulse pressure: it is differential pressure of systolic and diastolic pressure – 40mm Hg Mean atrial pressure – average pressure on the arteries
- 58. REGULATION OF BLOODPRESSURE: SHORT TERM REGULATION OF BLOOD PRESSURE: • BARORECEPTOR REFLEXES • CHEMORECEPTOR REFLEXES • CNS ISHCHAEMIC RESPONSE • SHIFT OF CAPILLARY FLUID LONG TERM REGULATION OF BLOOD PRESSURE • REGULATION OF VOLUME OF EXTRACELLULAR FLUID • RENIN- ANGIOTENSIN MECHANISM HORMONAL CONTROL
- 59. Baroreceptors reflex: Baroreceptorsare receptors found in carotid sinus & aortic arch. They are stimulated by changes in BP. BP + Baroreceptors Stimulate Para Sympathetic nerve Stimulate Sympathetic nerve Heart contractility & vasoconstriction Heart contractility & vasoconstriction Decrease in blood pressure Increase in blood pressure
- 60. Chemoreceptors reflex: ■ Chemoreceptorsare receptors found in carotid & aortic bodies. ■ they are stimulated by chemical changes in blood mainly - hypoxia ( O2), hypercapnia ( CO2), & pH changes. Chemoreceptors Vasomotor centre in heart rate & stroke volume Decreased partial pressure of oxygen Increase in the blood pressure Increased partial pressure of oxygen
- 61. CNS ISHCHAEMIC RESPONSE Ifthe blood pressure reduces to less than 50mm Hg & Increased partial pressure of CO2 Vasomotor centre stimulated by this Increase in the sympathetic activity Increases heart rate BP turns to normal
- 62. Shift of capillaryfluid: • Capillary pressure is directly proportional to arterial pressure • When arterial pressure is more the fluid present in the capillaries start passing out to the capillary • Automatically blood pressure comes to normal
- 63. LONG TERM REGULATIONOF BLOOD • Regulation of volume of extracellular fluid: Increase in volume of extra cellular fluid ↓ Which increases blood volume ↓ Thus increases arterial blood pressure ↓ The kidney excrete excess amount of water and salt ↓ There by reducing the ECF volume ↓ Brings the blood pressure to the normal
- 64. RENIN – ANGIOTENSINMECHANISM: Hypotension ↓ Low blood flow to the kidney ↓ Secretes renin ↓ Renin converts Angiotensinogen to Angiotensin-I ↓ ACE- converts Angiotensin-I to Angiotensin-II ↓ Angiotensin-II is potent vasoconstrictor ↓ Increase Blood Pressure
- 65. HORMONAL CONTROL Hormonesmay increase or decrease blood pressure THYROXIN: increases systolic blood pressure Reduces diastolic blood pressure ANGIOTENSIN & SERATONIN: Increases blood pressure by vasoconstriction BRADYKININ & ACETYLCHOLINE: Reduces BP by vasodilatation
- 66. DISORDERS OF HEART: •Coronary heart disease – affect coronary blood vessel • Rhuematic heart disease – damage to heart muscle & valve • Congenital heart disease – due to genetic factor deformities of heart structure • Stroke: interruption of blood supply to brain • Peripheral artery disease (PAD) – Plaque in peripheral artery ( supply blood to limbs & heart) • Deep vein thrombosis - blood clots in the vein – carried to the heart • pulmonary embolism – blood clots in the vein – carried to the lungs Hypertension – High blood pressure > 140/90mm Hg Hypotension – Low blood pressure < 90/60 mm Hg • Angina pectoris – chest pain - decreased blood supply to heart • Myocardial ischemia – imbalance btn supply and demand of oxygen • Myocardial infarction – due to loss of blood supply – death of heart cell • Congestive heart failure – heart fails to pump blood from ventricle • Cardiac arrhythmia – irregularities in cardiac rhytham • Arteriosclerosis – formation of fibrofatty plaques in tunica intima layer of arteries
- 67.