HBL-7 Cardiovascular System PDF

HBL-7: CARDIOVASCULAR SYSTEM DR. NANG THINN THINN HTIKE M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) Life Science, Japan SENIOR LECTURER, PHYSIOLOGY UniKL (RCMP) LEARNING OUTCOMES i. Describe the structure and function...

HBL-7: CARDIOVASCULAR SYSTEM DR. NANG THINN THINN HTIKE M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) Life Science, Japan SENIOR LECTURER, PHYSIOLOGY UniKL (RCMP) LEARNING OUTCOMES i. Describe the structure and functions of the heart ii. Describe the structure and of the arteries veins and capillaries Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan CONTENTS i. Functional Anatomy of the heart ii. Functional Anatomy of the blood vessels and lymphatics iii. Functions of the heart iv. Functions of the arteries, veins and capillaries Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan Circulation of the Blood Circulatory System Serves as a transport system Blood – fluid medium carrying various substances to be transported Blood vessels – a set of tubes through which the blood flows Heart – 2 sided m/s pump, drives blood along vessels Lymph & lymphatic Blood vessels + Heart = Cardiovascular system Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan  Major Systemic Circulation Start– LV, End– RA Arterial system – oxygenated Venous system – deoxygenated High pressure and high resistance circulation The lesser Pulmonary Circulation Start– RV, End– LA Pulmonary Artery- deoxygenated The lesser Major Systemic Pulmonary Circulation Pulmonary Vein- oxygenated Circulation Low pressure low resistance circulation Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan Functional anatomy of the Heart Human heart is structural and functionally divided longitudinally into right and left halves (Rt heart and Lt heart); each consisting of two chambers: an atrium and a ventricle) There are one way valves between atria and ventricles and at the origin of the aortic and pulmonary arteries. Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan  Valves of the Heart Rt heart Lt Heart Atrioventricular valves Tricuspid Mitral Semilunar valves Pulmonary Aortic The atria and ventricles are completely separated by a single fibrous skeletal which comprises 4 interconnected rings of dense connective tissue. To this skeleton are attached the musculature of the atria (to the top) and ventricles (to the undersurface) and four set of valves. Valves on both sides open & close simultaneously Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan How blood flow from the heart! Heart function as a Pump Atrial Syncytium : both atria contract simultaneously to push blood into the respective ventricle Ventricular Syncytium : both ventricles contract simultaneously to push blood into the respective artery Primer Pump : atria Primary Pump : ventricles Systole Phase Contraction; ↑ Pressure → opening of valve in front and closing of valve behind → emptying of the chamber → ↓ of volume after Ejection/emptying (atrial contraction follow by ventricular contraction) Diastole Phase Relaxation: ↓ Pressure → opening of Atrioventricular valve and closing of semilunar valve → filling of the chamber → ↑ of volume i.e. ventricular Filling Filling = Emptying i.e. Normal if Filling ≠ Emptying i.e. heart failure Closing of valves produces Heart Sounds Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan  Phases of cardiac cycle Stroke volume : volume of blood pumped by each ventricle per beat ≈ 70 ml Cardiac output : volume of blood pumped by each ventricle per min = 5 - 6 L Diastole (Relaxation stage) Isovolumetric ventricular Relaxation Ventricular filling Systole (Contracting stage) Isovolumetric ventricular Contraction Ventricular ejection  Origin and spread of cardiac excitation/Impulses SA Node : pacemaker ↓ Lt and Rt atrium muscle cells ↓ AV Node ↓ Bundle of His ↓ Right & Left Bundle branch ↓ Purkinje fibers ↓ Cardiac conduction system Ventricular Muscle cells Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan  Coronary circulation Aorta gives rise to 2 arteries Right coronary artery : Supplies right side of heart Left coronary artery : Branches into left circumflex artery and left anterior descending artery Supplies left side of heart Blockage by arthrosclerosis → ↓ blood flow of the heart Partial blockage → chest pain / angina Total → heart attack / infarction Medical Emergency Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan  Nerve supply of the heart Normal Heart rate : 60 - 100 beats / min Sympathetic nerve stimulation → Noradrenaline release → ↑ rate and force of contractions Parasympathetic nerve stimulation → Acetylcholine release → ↓ rate and force of contractions Increase HR  Tacchycardia Decrese HR  Bradycardia Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan  Blood vessels Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan Arteries (Damping vessels) Structure Large amount of elastic tissues (Elastic arteries) Elastic Reservoir known as” Windkessel” in German Function Damp/stabilized huge pressure fluctuation occur with each cardiac contraction Give a fairly steady driving pressure for tissue perfusion by means of elastic recoil (Windkessel effect) Acting as secondary pump during diastole phase to maintain the blood flow forward. Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan  Arterioles (Resistance vessels) Structure Function Less elastic tissues Major site of resistance to blood flow More smooth muscles with Regulate systemic arterial blood cholinergic and adrenergic pressure by tap like phenomenon by receptors (muscular arteries) regulating arteriolar contraction Regulate the blood flow to different organs Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan Fig: Normal blood pressures in the different portions of the circulatory system when a person is lying in the horizontal position. Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan Capillaries (Exchange vessels) Structure Single layer of endothelial cells Function Exchange of materials by diffusion between blood plasma and ISF. Eg. Respiratory gases and metabolites Veins and venues (Capacitance vessels) Structure Thinner walls (less elastic tissues and muscles) with larger lumen Function Greater capacity to store blood When blood is needed, shunted the blood into systemic arterial circulation by venoconstriction. Eg when fall in arterial pressure Dr.Nang Thinn Thinn Htike, M.B.,B.S, M.Med.Sc (Physiology), Doctor of Science (D.Sc) (Life Science) Japan