Transcript Slide 1
THE HEART Position of the Heart human heart is about the size of a fist lies in the thoracic cavity w/in the mediastinum (area from sternum to vertebrae, between the lungs) tilted @ angle so its inferior surface lies against the diaphragm Parts of the Heart Base of the heart is its superior border Apex of the heart is lowest point Major Heart Structures: the Pericardium Outer Layer: Fibrous Pericardium tough, attaches to diaphragm Inner Layer: Serous Pericardium dbl membrane: ○ outer parietal: attaches to fibrous pericardium ○ inner visceral layer: covers cardiac muscle between the 2: pericardial cavity filled with serous fluid Wall of the Heart 3 layers 1. outer epicardium same as visceral pericardium middle myocardium 2. cardiac muscle inner endocardium 3. thin layer of endothelium that lines inside chambers of the heart & valves Surface Features of the Heart 4 chambers of heart: 2 atria form the base ○ Auricles (ear-like) pouch-like extensions tip of left ventricle forms the apex Sulci: grooves where coronary blood vessels & adipose tissue that externally mark the boundaries between the 4 heart chambers ○ coronary sulcus: separates atria from ventricles ○ anterior & posterior interventricular sulcus: separate 2 ventricles Right Atrium Receives deoxygenated blood from SVC & IVC Right Atrium inside surface has honeycombed appearance & ridges called pectinate muscles wall separating rt & lt atrium= interatrial septum: in fetus hole called foramen ovale (blood shunts from rt atrium lt atrium avoiding pulmonary circulation); when scarred over called fossa ovalis Right Ventricle receives blood from right atrium sends blood to pulmonary trunk lungs to be oxygenated Right Ventricle inside has ridges of muscles called trabeculae carnae: largest ones called papillary muscles: have string-like cords called cordae tendinae Right Ventricle separated from left ventricle by: interventricular septum Left Atrium receives oxygenated blood thru 4 pulmonary veins delivers blood to left ventricle seen on posterior surface of heart Left Atrium thin-walled identifiable characteristic: 4 pulmonary veins entering it Left Ventricle receives oxygenated blood from left atrium sends blood to systemic circulation thru Aorta has thickest muscle (pumps blood the farthest) 4 Heart Valves control 1-way flow of blood 2 AV valves between atria & ventricles Tricuspid : rt AV valve Mitral : lt AV valve, aka bicuspid 2 semilunar valves blood exits rt ventricle thru Pulmonary (semilunar) valve blood exits lt ventricle thru Aortic (semilunar) valve AV Valves Tricuspid valve Mitral Valve Semilunar Valves Pulmonary Valve Aortic Valve Blood Flow thru the Heart thinner walled atria receive blood returning to heart from veins pressure of blood in filled atria opens the AV valves & most of the blood flows into ventricles both atria contract simultaneously to pump remaining blood into ventricles Blood Flow thru the Heart when atria have stopped contracting AV valves close Ventricles contract together forcing semilunar valves open walls of left ventricle thicker providing more force to pump blood thru systemic circulation Blood Flow thru the Heart Ventricular Systole: when both ventricles are contracting AV valves close Semilunar valves open Ventricular Diastole: when both ventricles relaxed Semilunar valves close AV valves open Cardiac Cycle Systemic & Pulmonary Circulation Heart Animations http://www.nhlbi.nih.gov/health// dci/Diseases/hhw/hhw_pumping.ht ml http://www.hybridmedicalanimatio n.com/work/animation/beatingheart-with-blood-flow/ Heart Sounds Auscultation: listening to body sounds 1 heartbeat produces 2 heart sounds: lub-dub heart murmurs: abnl heart sounds usually due to valve abnl http://www.blaufuss.org/tutorial/i ndex1.html Heart Sounds http://www.dnatube.com/video/92 17/Review-of-heart-sounds http://familymedicine.osu.edu/prod ucts/physicalexam/exam/flash/hea rt/heart2.cfm http://www.blaufuss.org/tutorial/i ndex2.html Pulse when ventricles contract a blood pressure wave is produced that travels in the arteries and can be felt as your pulse radial pulse: check over radial artery carotid artery pulse: check over carotid artery Calculate Pulse Count the # of beats in 15 s and multiply x 4 If the math is too difficult count for 30 s and multiple x 2 Blood Pressure pressure exerted by blood against blood vessel walls highest in the aorta & large elastic arteries & decreases as arteries get smaller & further from heart Systolic Blood Pressure top # on a BP pressure generated by ventricular systole normal adult: ~120 Diastolic BP bottom # on BP pressure exerted during ventricular diastole normal adult: 60- 80 Arterial Blood Pressure normal adult ~ 120/80 normal venous BP: ~16 mm Hg BP Measurement Sphygmomanometer: BP cuff usually use brachial artery use correct size cuff BP pump used to inflate cuff to a pressure > the systolic pressure: puts pressure on the artery, flattens it, & stops blood flow in the artery pressure slowly released from cuff as stethoscope used to auscultate over brachial artery BP reported in mm Hg as pressure in cuff becomes < pressure in artery…examiner will hear a sound can be heard, caused by the turbulent flow of blood as artery goes from flattened normal