Cardiovascular System F2024 PDF

Cardiovascular System S. THEMISTOCLEOUS, MSc. BSc Medicine Program Medical School https://www.britannica.com/science/atherosclerosis#ref921978 A. Ishii, F. Viñuela, Y. Murayama, I. Yuki, Y.L. Nien, D.T. Yeh and H.V. Vinters American Journal of Neuroradiology October 200...

Cardiovascular System S. THEMISTOCLEOUS, MSc. BSc Medicine Program Medical School https://www.britannica.com/science/atherosclerosis#ref921978 A. Ishii, F. Viñuela, Y. Murayama, I. Yuki, Y.L. Nien, D.T. Yeh and H.V. Vinters American Journal of Neuroradiology October 2006, 27 (9) 1893-1899;  Heart Cardiovascular Veins System Arteries Capillaries  Lecture Outline Cardiovascular System Basics Heart Vessels Cases  Cardiovascular System Components: Heart- muscular organ that pumps blood the system Arteries- multiple vessels efferent from the heart. They become smaller as they branch our into organs carrying blood to the tissues Capillaries- smallest vessels. Site of O2 exchange, CO2, nutrient and waste products Veins- from venules to larger veins that continue to get bigger as you move closer to the heart Function: to carry oxygen, nutrients, waste products and hormones  Circulatory system Systemic Circulation – part of the circulatory system that carries nutrients and 02 (oxygenated) to tissues and organs. blood leaving tissues carrying waste away. Simultaneously it carries deoxygenated blood, along with waste products, back to the heart. Pulmonary Circulation - arteries, veins and microvasculature. It is responsible for carrying deoxygenated blood from the heart to the lungs and returning oxygenated blood back to the heart  Cardiovascular System Basics Blood flows through the Cardiovascular System: Heart → elastic (large) arteries → muscular (medium-sized) arteries → small arteries → arterioles → capillaries → venules → small veins → medium veins → large veins → heart https://en.wikipedia.org/wiki/File:Sankey_diagram_human_circulatory_system.svg Lymphatic Vascular System Network of vessels, nodes and organs: Lymphatic vessels- network of thin-walled tubes that run parallel to blood vessels throughout the body transferring a clear, colourless fluid=lymph Lymph- water, proteins, lymphocytes, lipids, wastes etc. Immune response Transport of White Blood Cells Maintains fluid balance Lymphatic Organs- Spleen, tonsils, thymus Simple Squamous Epithelium Endothelium Imagine you are a red blood cell running through the cardiovascular system. What would you see??  Endothelium https://doi.org/10.1016/j.transci.2022.103368  Endothelium The lumen of all blood and lymphatic vessels are lined with a simple squamous epithelium known as the endothelium. This epithelium creates a barrier between blood or lymph, control relaxation and contraction, releases molecules that attract WBC to the site of injury or infection promoting the immune response and prevent excessive bleeding. Endothelium is involved in angiogenesis Endothelium inside the heart chambers is known as endocardium  Endothelium Epithelial lining of the cardiovascular system Simple squamous epithelium Non-thrombogenic surface Role in inflammation & local immune response Acts as a semipermeable barrier Secrete growth factors Vascular endothelial cells in contact with blood in the lumen of blood vessels Lymphatic endothelial cells are in contact with the lymph 14  Lecture Outline Cardiovascular System Basics Heart Vessels Cases  Three layers of the Heart Endocardium Myocardium Epicardium https://florida.theorangegrove.org/og/file/2d684c74-16c7-54be-f3cf- 1a380b19e4d1/1/bbtraining.zip/instructional_design/12Leads/05.htm Heart Structure Endocardium- inner squamous endothelium with a middle layer of connective tissue & smooth muscle and a deeper layer of connective tissue (subendocardial layer). Conducting system found here and well as lining the valves Myocardium- cardiac muscle tissue with intercalated discs. thinner in atria than ventricles due to excessice force required by ventricles to push blood out of the heart Epicardium- single layer of mesothelial cells an underlying connective & adipose tissue. The coronary circulation vessels lay here Endocardium Epicardium Thin endocardium and supporting Simple squamous mesothelium connective tissue. Follows by supported by loose connective tissue myoelastic muscle fibers and containing blood vessels and nerves connective tissue & fibers of nerve impulse Epicardium(visceralpericardium) Thecoronaryvessels arelocated here!  Myocardium Muscle fibers arranged in a spiral manner. Walls are thicker in ventricles than in atria.  Myocardium Middle layer of the heart (analogous to the media in vessels) Mainly composed of cardiac muscle cells (striated muscle cells due to sarcomeres); it also contains a very rich network of blood vessels Cardiac muscle cells (fibers) are branched and arranged around the heart chambers Intercalated discs: composed of several types of cell junctions that glue adjacent cells together Myocardium: notice thebranching ofthe cardiac muscle cells  Intercalated Disks Aid the conduction system of the heart Electrical→ Contain gap junctions allowing for rapid exchange of ions ( Na+, K+ and Ca2+ and others). Coordinated unit Mechanical→ as a cardiac muscle cell contracts the desmosomes distribute this force and transmit it to neughbouring cells This Photo by Unknown Author is licensed under CC BY-SA-NC  Endocardium, Myocardium, Epicardium http://141.214.65.171/Histology/Cardiovascular%20System/098HE_HISTO_40X.svs/view.apml?X=0&Y=0&zoom=0.639868422083343 Endocardium Myocardium Epicardium  Fibrous Skeleton Dense fibrous network connective tissue Encircle the aorta, bases of the pulmonary Fibrous trunk and heart valves Skeleton Isolates atria from ventricles Electrical insulation- Stops contraction from continuing and therefore need to follow the signal by the nodes (electrical insulation ) Anchor & support the heart valves Provide firm points for anchoring of cardiac muscle  Systemic Right Circulation ventricle Left Pulmonary ventricle artery Left Capillaries in Atrium lungs Pulmonary veins  Heart Beat Sinoatrial node is located in the right atrium of the heart and once its polarized it generates electrical impulses almost spontaneously Electrical impulse travels through the atria depolarizing them and forcing blood into the ventricles (Atrial Depolarization) Rate of depolarization is fastest in the atria than ventricles due to the atrioventricular node acting as a delay to ensure the ventricles fill up The electrical impulse from the AV node is then transmitted through the bundle of His to the apex of the heart along the interventricular septum separating left & right ventricles along the Purkinje fibers https://gfycat.com/agonizingselfishbronco-collisions-conduction-particles-physics Parasympathetic Nervous System: "rest and digest" system Primarily responsible for slowing down the heart rate and promoting relaxation. The main parasympathetic nerve that innervates the heart is the vagus nerve (cranial nerve X). Releases acetylcholine = bradycardia Decreases force of heart contractions, reducing cardiac output Sympathetic Nervous System: "fight or flight" system Increases heart rate and cardiac output Response to stress or physical exertion. Release norepinephrine, which binds to beta- adrenergic receptors on the heart's cells. Increases heart rate (tachycardia) & increases force of heart contractions, enhancing cardiac output  Purkinje Fibers (stain lighter than the classic cardiac muscle fibers) http://www.histologyguide.com/slide-view/MHS-245-heart/09-slide-1.html?x=4989&y=22266&z=52.2&page=1  Subendocardium Subendocardium is the part of the endocardium attached to the myocardium It is composed of connective tissue but also contains the Purkinje fibers (specialized cardiac muscle cells) of the conducting system Purkinje fibers are larger and paler than the conventional cardiac muscle cells (due to intracellular glycogen deposits) Their main function is to conduct the contraction signal over both ventricles https://anatomyinfo.com/purkinje-fibers/  Tricuspid valve Atrioventricular valve Three cusps or leaflets Connected to the papillary muscles within the right ventricle by chordae tendineae Papillary muscles are small, cone-shaped muscles within the right ventricle Prevent the backflow of blood from the right ventricle into the right atrium  Bicuspid Valve Location: Between the left atrium and the left ventricle. Structure: It has 2 cusps (hence "bicuspid"). Function: It allows blood to flow from the left atrium into the left ventricle and prevents backflow into the atrium when the ventricle contracts. A.K.A Mitral valve Cusps of the valve are connected to the papillary muscles within the left ventricle by chordae tendineae (fibrous DOI: 10.1080/01926230213166 cords of connective tissue) Aortic valve Location: Between the left ventricle and the aorta. Structure: It is a semilunar valve with three cusps or leaflets. Function: Prevents the backflow of blood from the aorta into the left ventricle after the ventricle contracts. 2 or 4 cusps Have Chordae Tendineae (fibrous cords of connective tissue) The papillary muscles are cone-shaped muscles located within the left ventricle. Pulmonary Valve Typically has 3 cusps or leaflets These cusps are thin, membranous structures The three cusps are often referred to as the anterior, left, and right cusps. Deoxygenated blood to be pumped from the right ventricle to the pulmonary circulation. The cusps of the pulmonary valve are attached to a fibrous ring called the annulus. Chordae tendineae connect the cusps of the pulmonary valve to the papillary muscles within the right ventricle https://doi.org/10.3389/fcvm.2022.829120 Heart https://www.youtube.com/watch?v=SC5fKdrYi6w&t= 987s https://www.youtube.com/watch?v=ZcCviyMNsPo https://www.youtube.com/watch?v=oS4XA749GoI