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U4: Heart
| Question | Answer |
|---|---|
| Heart | Muscular pump for cardiovascular system; R receives deoxygenated blood, pumps to lungs; L receives oxygenated blood from lungs and pumps to body |
| Pulmonary circuit | blood vessels into which the R side of the heart pumps blood to lungs & by which blood is returned from the lungs to the L side of the heart |
| Systemic Circuit | blood vessels into which the left side of the heart pumps blood to the overall body, and by which blood is returned from the body tissues to the right side of the heart |
| About size of a person's fist; located in mediastinum of thoracic cavity, between lungs and deep to sternum; ab. 2/3 lies to left of thorax midline | size and location of heart |
| Apex | the inferior point of the heart; positioned left of midline and immediately above diaphragm |
| Auricles | left and right flap-like structures that make up much of superior heart surface |
| Pericardium | membranous sac that encloses heart; consists of outer fibrous and inner serous |
| Fibrous pericardium | outer layer of pericardium; composed of tough, dense fibrous connective tissue that loosely fits around heart, yet helps hold it in place |
| Serous pericardium | inner layer of pericardium; consists of outer parietal layer and inner visceral layer |
| Parietal Pericardium | outer layer of serous pericardium; lines the inner surface of fibrous pericardium which together form the pericardial sac |
| Pericardial sac | surrounds heart; formed by fibrous pericardium and parietal pericardium |
| Visceral Pericardium | layer of the serous pericardium; clings directly to heart and is the outer layer of the heart wall itself |
| Pericardial Cavity | thin, slit-like space between the parietal and visceral pericardium that contains a film of lubricating serous fluid. |
| Pericarditis | inflammation of pericardium; can lead to deficit of pericardial fluid resulting in painful friction felt behind sternum; sometimes results in adhesions causing parietal & visceral layer to stick together interfering w/ normal heart movements. |
| Cardiac tamponade | buildup of excess serous fluid in pericardial cavity or presence of blood in cavity can compress heart, limiting expansion b/t beats and capacity to pump; treated w/ insertion of hypodermic needle into pericardial cavity to remove excess fluid/blood. |
| Epicardium, Myocardium, Endocardium | three layers of heart wall |
| Epicardium | outer layer of heart wall; serous membrane component |
| Myocardium | thick, middle layer of heart wall; forms bulk of wall; mainly cardiac muscle, provides heart beating/pumping capability; increase in size/strength of this layer in those that exercise regularly and vigorously |
| Endocardium | thin, inner layer of heart wall; lines heart chambers & coats valves; can get inflamed from bacteria in bloodstream |
| Endocarditis | inflammation of endocardium due to bacteria in bloodstream |
| Right & left atria, right & left ventricles | the four chambers of the heart |
| Atria | superior chambers of heart; primarily serve to receive blood returning to heart via major veins of the body |
| Ventricles | inferior chambers of heart; receives blood from atria through valves; walls are thick w/ cardiac muscle, allowing them to serve as discharging (pumping) chambers |
| Interatrial septum | separates right and left atria |
| interventricular septum | separates right and left ventricles |
| Coronary/atrioventricular sulcus | groove on external surface of heart at external boundary of atria and ventricles |
| Anterior and Interventricular Sulcus | groove on external surface of heart mark external boundaries between the two ventricles |
| Right Atrium | covered by flap-like right auricle; receives oxygen poor blood from 3 systemic veins (superior vena cava, inferior vena cava, coronary sinus); contains fossa ovalis |
| Fossa Ovalis | spot where foramen ovale was present in fetal heart which allowed blood to pass directly from right to left atrium, bypassing pulmonary circuit and lungs in fetus |
| Left Atrium | covered by left auricle; receives oxygenated blood via 4 pulmonary veins |
| Right Ventricle | receives oxygen-poor blood from right atrium and pumps this blood toward lungs via pulmonary trunk artery |
| Left Ventricle | forms most of inferior aspect of heart; receives oxygen-rich blood from left atrium and pumps this blood to overall body via a systemic artery named the aorta. |
| Heart Valves | four of two different types - 2 atrioventricular and 2 semilunar |
| Allow blood to flow in only one direction through heart | function of heart valves |
| Right and left Atrioventricular (AV) Valves | valves located b/t atrial and ventricular chambers on each side of heart; allow blood to flow from atria into ventricles, and normally prevent backflow into atria when ventricles contract |
| Tricuspid valve | specific name for right AV valve |
| Bicuspid/mitral valve | specific name for left AV valve |
| Chordae tendineae | tiny, tough strings that extend from cusps (flaps) of AV valves to papillary muscles of ventricles; help anchor cusps into proper positions |
| Papillary muscles | small projections on internal surface of ventricles; along with chordate tendineae help anchor cusps into proper positions |
| Semilunar Valves | located at bases of pulmonary trunk and aorta; called the pulmonary semilunar valve and aortic semilunar valve; consist of cusps that open when ventricles contract |
| "Lub Dup" | "sound" of heart; related to the closure of valves; lub is closure of the AV valves; dup is closure of semilunar valves |
| Murmurs | abnormal or unusual heart sounds that usually indicate heart valve problems, many of which aren't serious; via stethoscope, distinct sounds can be heard in assoc. w/ diff. types of valve problems |
| Incompetent valve | valve disorder in which valve forces heart to pump & repump the same blood due to improper valve closure causing backflow of blood; such a valve exhibits "insufficiency" |
| Mitral Valve Prolapse | incompetent valve cond; most common b/c bicuspid/mitral valve subj to substantial pressure from L vent contraction; cusps flop out of normal pos. & protrude into L atrium during contraction of L vent allowing backflow into atrium; most cases harmless |
| Valvular stenosis | type of valve disorder; cusps of valve become stiff so don't fully open forcing heart to contract more vigorously to pump blood thru smaller opening; "stenotic valve" can be replaced w/ synthetic or pig valve |
| Fibrous skeleton of the Heart | made of dense fibrous connective tissue, provides actual structural support for heart, blocks direct spread of electrical impulses from atria to ventricles |
| Intrinsic Conduction System of Heart | cardiac muscles contract via self-stimulation provided by this system; brings about heart muscle stimulation from atria to ventricles only and is responsible for avg heart rate of 70-80 beats/min |
| Main components of heart’s intrinsic conduction system | components are modified cardiac muscle cells that do no contract; sinoatrial (SA) node, atrioventricular (AV) node, atrioventricular (AV) bundle (bundle of His), right & left bundle branches, Purkinje fibers |
| Sinoatrial (SA) node | located in wall of right atrium, near where superior vena cava opens into this chamber; called the “pacemaker” b/c it initiates electrical signals that initiate each heart beats |
| Atrioventricular (AV) Node | located in lower part of ineratrial septum; acts as electrical gateway to ventricles b/c fibrous skeleton prevents electrical impulses from reaching ventricles. |
| Artrioventricular (AV) Bundle | enters the interventricular septum and divides to give rise to right and left bundle branches which pass down thru the interventricular septum |
| Purkinje fibers | spread through myocardium of ventricles; impulses spread through them stimulating both ventricles to undergo simultaneous contraction |
| Heart Block | destruction of AV node and AV bundle via myocardial infraction (heart attack) can isolate ventricles from the control of the SA node/pacemaker, causing this condition. Ventricles will still contract, but out of synchrony relative to atria and too slow |
| Extrinsic Neural Regulation of Heart Rate | Via sympathetic (SA node) and parasympathetic (vagus nerve) divisions of the ANS, the heart rate can be increased/decreased as needed; controlled by reticular formation aspect of medulla oblongata |
| Cardioinhibitory center | located in reticular formation aspect of medulla oblongata; parasympathetic related |
| Cardioacceleratory center | located in reticular formation aspect of medulla oblongata; sympathetic-related |
| Tachycardia | heart rate more rapid than normal |
| Bradycardia | heart rate significantly lower than normal |
| Blood vessels of the Heart Wall (coronary circulation) | arterial supply, venous drainage |
| Arterial Supply | heart has its own network of arteries to supply wall w/ oxygenated blood; R & L coronary arteries, ascending aorta, anterior interventricular & circumflex arteries, posterior interventricular & marginal arteries |
| Venous Drainage | cardiac veins carry deoxygenated blood from heart wall; largest is coronary sinus |
| Coronary Sinus | largest venous drainage vein; located on posterior surface of heart; receives blood from other cardiac veins and empties its blood directly into right atrium |
| Coronary artery disease | narrowing of coronary arteries such that in adequate flow of oxygenated blood to myocardium; most often caused by atherosclerosis; may cause angina, which can indicate myocardial infarction |
| Atherosclerosis | accumulation of fatty deposits in arterial wall that results in obstructed blood flow |
| Angina Pectoris | crushing chest pain that can be caused by insufficient supply of oxygenated blood to myocardium; can be a warning of ischemia |
| Ischemia | inadequate supply of oxygenated blood; can cause cardiac cells to die resulting in myocardial infarction |
| Myocardial infarction | heart attack; caused by extensive inadequate supply of oxygenated blood which causes cardiac muscle cells to die; often associated w/ ventricular fibrillation |
| Ventricular fibrillation | characterized by rapid uncoordinated shuddering contractions of the heart that make it look somewhat like a bag of worms; can lead to inadequate circulation of oxygenated blood to heart, resulting in cardiac arrest and death |
| Congestive Heart Failure (CHF) | occurs when pumping efficiency of heart is reduced to point that circulation is inadequate to meet body tissue needs; usually progressive condition reflecting chronic high blood pressure, multiple myocardial infarctions, or coronary artherosclerosis |
| Peripheral Congestion | occurs when right side of heart fails; especially demonstrated by swollen & puffy hands, feet, ankles; heart cannot pump away blood it’s receiving from peripheral parts of body, causing blood to pool causing edema |
| Pulmonary congestion (pulmonary edema) | occurs when left side of heart fails; causes buildup of excess fluid in lungs that interferes w/ diffusion of oxygen into blood and may lead to suffocation |
| Congenital Heart Defects | 1/150 of newborns has some sort of heart defect; include patent foramen ovale and ventricular septal defect |
| Patent (non-closed) foramen ovale | congenital heart defect; failure of foramen ovale to close at time of birth; normally foramen ovale closes to form fossa ovalis @ time of birth |
| Ventricular septal defect | most common congenital heart defect; failure of superior part of interventricular septum to form during fetal development, thus leaving open gap b/t two ventricles which blood can pass through |
Created by:
mbtrimm
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