Heart and Circulatory system DTH21 GN.pdf
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The Heart and Circulatory System Learning Outcomes At the end of the session students will be able to: Describe the heart Explain the structure of the heart Describe the flow of blood through the heart Understand the conduction system of the heart Describe blood supply to the heart...
The Heart and Circulatory System Learning Outcomes At the end of the session students will be able to: Describe the heart Explain the structure of the heart Describe the flow of blood through the heart Understand the conduction system of the heart Describe blood supply to the heart Describe the components of the circulatory system 2 2417 Pumps Opints blood - of Heart Beats - > 3 Smillion - times at end of eetime The heart is a hollow four chambered muscular organ roughly the size of a clenched fist Loading… The heart beats around 100 000 times a day It acts as two separate pumps; the right heart pumps blood to the lungs and the left heart pumps blood to the body Right heart-longs Left heart-body Image Pinterest Feb 2021 3 213ra(of midline with core shaped end - APEX.. Heart shape and position The heart is located in the thoracic cavity, in between the lungs, in a region known as the mediastinum It sits behind the breastbone (sternum) Most of the heart lies left of the midline, with its apex pointing downwards in contact with diaphragm. The base of the heart is the broad superior end, where the large vessels attach Image University of Michigan Feb 2021 4 pericarditis > - inflammation of pericardial sac accompanied by increase in secretion of pericardial fluid into pericardial Heart structure cavity As fibrous lawyer is tough and. inelastic , an increase in fluid pressure can compress the heart and impair movement of blood in or out. The heart is enclosed and protected by the parietal pericardium (or pericardial sac) which separates the heart from other thoracic organs and forms the wall of the pericardial cavity pericardial fluid Loading… which contains The parietal pericardium is composed of an outer fibrous and an inner serous layer The serous layer secretes the pericardial Image Heart Valve Surgery Website Feb 2021 fluid as the heart beats acts to reduce friction 5 thickness varies different myocardium an chambers of the recent. Heart structure – Heart wall The wall of the heart is comprised of three distinct layers: -viceral lays Epicardium outer layer - Myocardium thick middle layer comprised of thick cardiac muscle I responsible for > - contraction - Endocardium smooth inner layer lining the heart and its internal Image Oregon State University Feb 2021 structures I of Endocardium= Endocarditis Inflammation bloodstream > - continuous with ↳ can be trigged by bacteria entering heart endothelium of blood vessels 6 through. mouth S 3 muscle types Atrial muscle - Simular to Skeletal though contraction last longs + automatic NS. Ventricular muscle - Specialized excitatory and conductive muscle fibres Heart structure – cardiac muscle Exists only in the heart of animals Controlled by the autonomic nervous system Fibres are branched and arranged in a striated pattern Cardiac muscle cells are and connected by intercalated discs consisting of fascia adherens, allow ions to - gap junctions and desmosomes L hold cells and to end pass between The regular arrangement and specialised cell cells, junctions allow the muscle to contract smoothly transmitting and repeatedly + quickly impulses. Image Quora Feb 2021 between. them 7 Heart structure - Chambers The heart is divided into four chambers the upper right and left atria and the lower right and left ventricles long) into atria flows from body + Blood The atria are receiving chambers which contract and empty into the ventricles. They are separated by a G thin muscular interatrial septum The ventricles are pumping chambers are are separated by a O thick muscular interventricular septum /Blood is under pressure to the propelled longs and rest of body. Grooved depressions on the surface of the heart /most indicate the partitions between the chambers and also contain cardiac vessels that supply blood to the heart wall Solcu prominant at recentricular groove/comory 8 atria+ ventricle 3 devision between Image Heart Foundation Feb 2021 Cardiac Cyc repeting pattern of contraction and relaxation of heart systole diastole Heart structure – right atrium and right ventricle The right atrium receives venous blood from the superior vena cava and the inferior vena cava upper body lower a body The cardiac cycle consists of a period of relaxation when the heart fills with blood (diastole) followed by a period of contraction (systole) During diastole blood passes from the right atrium to the right ventricle through the atrioventricular triscuspid valve & During systole when the right ventricle contracts 80 % of blood flow: the tricuspid valve closes preventing backflow of blood into the atrium Image Society of Thoracic Surgery Feb 2021 directly through atria into ventricles before contraction. 9 Contraction of atria adds final 20 %. Question If the atria fail the difference is unlikely to be noticed unless a person exercises – can you think why this might be? 10 Heart structure – left atrium and ventricle After gas exchange in the lungs oxygenated blood is passed to the left atrium from the pulmonary veins During diastole blood passes from the left atrium to the left ventricle through the bicuspid mitral Loading… valve During systole when the left ventricle contracts the mitral valve closes preventing backflow of blood into the atrium The left ventricle has thicker walls than the right ventricle - due to increased pressure needed. Oxygenated blood leaves the left ventricle via the aorta. The aortic semilunar valve prevents backflow from the aorta into the left ventricle. Image Thoughtco Feb 2021 11 Heart sounds When listening to the heart with a stethoscope we are listening to the turbulence created when the heart valves close S1 First heart sound (‘Lub’) systole S2 Second heart sound (‘Dub’) Diastole Problems with the valves may be detected by variations in these sounds known as heart murmurs ↳ turbulence of blood flow. 12 Heart structure Image Google Feb 2021 13 Heart structure – helpful videos https://anatomyzone.com/thorax/heart/heart-structure-and-function-basics/ https://www.youtube.com/watch?v=jBt5jZSWhMI heart Veins-Blood flowing to the the heart. Arteries - Blood flowing from 14 ①Deoxygenated Blood enters right atrium through Superior t inferior Vena Cava. ② Blood enters right ventricle through tricuspid value. ③ Blood exists right ventricle through pulmonary value and enters pulmonary artery , ④ Left Right pulmonary arteries Send blood to lungs for gas exchange. ⑤ Oxygenated Blood returns to heart via Pulmonary veins and enters the left atrium. ⑥ Blood enters left ventricle through mitral (bicuspid) value ⑦ Oxygenated blood exist left ventricle through aortic Semilunar value to enter aorta. ⑧ Aorta distribute oxygenated blood to rest of the body. Terms you should feel comfortable with diastole superior interventricular septum vena cava epicardium myocardium atria triscuspid aorta mediastinum valve parietal pericardium sternum semilunar valve pulmonary vein endocardium pericardial cavity pericardial gap junctions fluid systole mitral valve interatrial septum 15 Heart structure - Test your knowledge Ensure you can label the diagram of the structure of the heart correctly arteries Aortu Pulmonary veins. vena pulmonary Cara atrium ↓ left atrium Imad & tricuspid mitral (Bicuspid) value value right left ventricle ventricle Inter Aortic ventricular semilunar septum value. 16 The conduction system of the heart Nodes + specialized Cells & initiate contractions of heart muscel Consists of: Sinoatrial node Atrioventricular node Bundle of His Purkinje fibres 17 Right + left Atria contract almost simultaneously followed by contraction of right + left ventricles The conduction system of the heart 0 1-0 2 seconds.. later Each heartbeat begins in the heart’s pacemaker known as the the sinoatrial or SA node superior near The SA node is located in the right atrium Vena Cava During diastole the SA node exhibits a opening spontaneous depolarisation called the pacemaker potential The wave of depolarisation spreads across the atria resulting in atrial systole then converges at the atrioventricular or AV node The AV node delays the impulses to allow the atria time to fully empty into the ventricles The Bundle of His conducts impulses to the Purkinje fibres of the ventricles resulting in ventricular systole Image Medic Tests Feb 2021 18 The conduction system of the heart – Electrocardiogram (ECG) An ECG is an important non-invasive test that provides information about heart rate and rhythm It measures the electrical activity generated when the heart contracts and records this as a trace consisting of: P wave QRS complex T wave ECG can help detect abnormal heart rhythms (arrythmias), an enlarged heart due to high blood Image Cardiovascular concepts Feb pressure (hypertension), heart attacks (myocardial 2021 infarction) among other conditions 19 Electrocardiogram (ECG) 20 Image Gfycat Feb 2021 The conduction system of the heart – helpful video https://www.youtube.com/watch?v=NijiLTONHxg conduction of heart-electrical current specalised. at rest Heart muscle is Negative charge - - need positive contraction charge for. Depolarization-negative charge - positive charge - without this muscles wouldn't contract 21 Atrea node (SA) Sinus rhythm u Synoatrial - - + --Sends At rest - , Spontaneously goes wave charge of - throughatrial musel Catrialmyocardium) fibrous tissue that separates atria from ventricles stops ↑ + charge - Atrioventricular mode (Av) - Sits between atria - ventricles Ftsec delay lands + charge through Bundle HIS there branch through heart of off muscles - ventricular. Heart muscle has depolarized This all reverses heart Arteries - veinscapillaries The circulatory system Also known as the cardiovascular system Circulates blood, transports nutrients, oxygen and hormones, removes waste products and controls homeostasis Pulmonary truck semilunar value Pulmonary circulation transports blood from the right ventricle to lungs and then the Primonary arteries left atrium to the heart ↳ pulmonary pulmonary capillaries veins Peripheral - Systemic circulation composed of all the remaining vessels of the body that are not part of the pulmonary system 1 Aorta Image Research gate Feb 2021 23 Systemic The circulatory system - Coronary circulation The heart has its own circulation known as the coronary circulation It consists of the right and left coronary arteries delivering oxygenated blood to the heart From capillaries in the myocardium blood enters the cardiac veins into the right atrium Left ventricle supplied by left coronary artery · ↳ Blockage catastrophic = Image Google Feb 2021 24 Circulatory system - Foetal circulation In utero the pulmonary circulation is unnecessary because foetal blood is oxygenated by the placenta The umbilical cord serves as the connection between foetus and placenta Systemic venous blood returning to the right atrium is deflected through the foramen ovale to the left atrium Blood from the left ventricle is diverted away from the pulmonary arteries, to the aorta, through the ductus arteriosus Image Google Feb 2021 25 S types of Circulatory system – Blood vessels to tissues. transport blood under high pressure ↑ branch of artery function 1.to Arteries last small fluids , act ascontra into exchange 2. hormones , Arterioles -system nutrients between , capillaries 3. electrolytes Capillaries interstitial fluid blood + 4. Venules -> collect blood from Capillaries 5. Veins X Transport blood from tissues back to heart and act as reservoir. Image Quizlet Feb 2021 26 Small-less clastic - smallersuman-so greater resistance to blood flow. Circulatory system - Arteries withstand muscular walls to Strong pressure. Carry oxygenated blood (except pulmonary system) away from heart Thick elastic muscular walls outer, loose Bloodflow under high pressure Connectissue 3 layers arteries tissues & Tunica externa - Contraction - Tunica media 4 Pressure rises Smoothmuscle Tunica intima + arteries expand fibres + ↓ & elastane lined Inner lays endothelium. by smooth Image Lumen learning Feb 2021 27 most total blood volume-venous system lower limbs of blood to heart - veins can expand when fulled with blood insufficient to return - squeezed by Skeletal muscle groups heart Circulatory system - Veins -create one way flow back to the stand still or inactive who - effective less people in 1 Carry oxygen depleted blood back to the heart · Respiratory Contain valves to prevent backflow/pooling upper. Act as a reservoir of blood pump for Rely on the skeletal muscle pump and respiratory pump Also have 3 layered walls but less muscular and less elastic than arteries Blood then acculimates in veins , they overstretch + values are no long effective Image Google Feb 2021 28 branches extensively Capillary. micrometers to located 60-00 all tissue cells Htotal surface area 1000 = squaremild Circulatory system - Capillaries artenioles - venioles extensive network small molecule Smallest and most abundant blood vessels in 3 types allowingthrough Skin , fatt body muscles neuver , Continuous no perforations - r more coles allow small - O Walls consist of endothelium only, one cell Fenestrated Small perforations Intesting Kidney through - + endoerin - ~ layer thick Discontinuous (sinudoidal) grands lack smooth of + - Loading… Permit rapid rate of exchange of oxygen, nutrients and waste products between blood C Large openings (sinusoids) : Allow Blood cell through Bone marrows liver , spleen muscle and tissues connec Tissue. Capillary beds are networks of capillaries supplying organs Blood flow through capillaries is determined by precapillary sphincter muscles and the constriction or dilatation of arteries and arterioles I + degree of resistancese- 29 Central nervous system the capillaries make up ↓ Circulatory system – Blood-brain barrier Substances can only cross through controlled transport channels under special circumstances· The blood-brain barrier acts as a boundary between circulating blood and the brain and spinal cord It is highly selective and protects the brain from ‘foreign’ substances and maintains a constant environment for the brain Brain capillaries are not fenestrated and their endothelial cells are very tightly packed so large molecules, immune cells, bacteria and viruses are prevented from passing from the blood to the central nervous system 30 Arteries and veins - Test your knowledge Ensure you can identify and label these blood vessels correctly 31 limbsp Vessels crite from aortic arch : · 1. Brachiocephalie truce Pper 3. left Subclavian - 2 Left common carotid Artery artery. Major blood vessels – the Great vessels Arteries Pulmonary artery Aorta Aortic arch Ascending and descending aorta The pulmonary arteries carry blood from the right atrium to the lungs for oxygenation The aorta originates from left ventricle as ascending aorta, forms the aortic arch becoming the descending aorta as it continues down through body Image David Darling Website Feb 2021 32 Major blood vessels – The Great Vessels Veins Pulmonary vein Superior vena cava Inferior vena cava The pulmonary vein returns oxygenated blood from the lungs to the left atrium The supervior vena cava receives deoxygenated blood from the upper body and the inferior vena cava receives the venous return from the lower body. Both drain into the right atrium Image News medical Feb 2021 33 Blood pressure Blood pressure is the force exerted by circulating blood against the artery walls Measured in millimetres of mercury (mmHg) Systolic/diastolic e.g 120/80mmHg ↓ S contraction of heart Left Ventricle relaxes Image Diabetes UK website Feb 2021 34 during day Higher · Age Question Lower at night systolic pressure ↳ elderly-higher Exercise Anxiety General Physical Health. What might cause blood pressure variation? 35 Circulatory system – helpful videos Blood pressure https://www.youtube.com/watch?v=keYtWNAJY64 Capillary exchange https://www.youtube.com/watch?v=dFRa2ECm5pY 36 THE END Further references: Waugh, A. and Grant, A. (2018) Ross & Wilson Anatomy And Physiology In Health And Illness. 13th ed. Elsevier. Ward, J. and Linden, R. (2017) Physiology At A Glance. 4th ed. Wiley-Blackwell. 37
