Week 2 - The Heart PDF

 19. The Heart Chapter The Cardiovascular System · made up of hearta b...

 19. The Heart Chapter The Cardiovascular System · made up of hearta blood vessels · deliver oxygen , nutrients , hormones through body t remove CO2 6 other wastes must be able to provide adequate perfusion ↳ Perfusion : of blood of tissue delivery per time per gram (mL/min(g) Blood vessel components A Away Arteries carry blood away from heart - = ↳ (not all blood most carry oxygenated reins carry blood to heart - blood. ↳ most (not all) carry deoxygenated Capillaries between blood + lungs & blood Sites of exchange - body cells. HeartWithin Thoracic Cavity · located in pericardium · posterior to sternum , left of body midline Base Postero Superior surface * Base Apex projection · - - , , , · Apex-pointed end Location * · Heart projects antero-inferiorly.  External Anatomy of Heart-Chambers : Anterior veiw : Left anricle of left atrium ① & Right Auricle Right Atrium Oxygen poor blood. Right Ventricle pumps blood ② Left Ventricle to langs to pick · thickest chamber up oxygen. ↳ pump blood out to whole body. Atriums - Always receive blood entering heart Ventricles - Always pump out blood from heart. Rightatriumt right Ventice-oxygen ORblo - lood Posterior View :  Vessels. External Anatomy : Anterior View : 2). I. -blood received from (above heart) upper body 2 - -to lungs C-blood to lungs 3. - fresh of blood in to left atrium. 3 - fresh of blood 7Shop back to heart a - I - supply heart muscles with blood Superior & inferior Vena Cava-Bring back deoxygenated blood from body to heart superior = bringing back blood from area above heart inferior = bringing back blood from area below heart. Pulmonary Trunk - Main Pulmonary Artery. Branches off to left↓ right pulmonary arteries. Pulmonary Arteries (Left) right) - carry oxygen poor blood from heart to lungs Pulmonary Veins (Left +right) Carry - oxygen rich blood from lungs to heart Ascending aorta-oxygen rich blood leaves the heart through ascending aorta in to systemic circulation around the body. Right Coronary artery , marginal artery , left Coronary artery circumflex , artery , Canterior interventricular artery - Supply Oxygen rich blood directly to working heart muscle. Posterior View : · act as blood reservoir · right coronary has anterior ↓ posterior arteries. Right Coronary Artery posterior interventriculary Artery , = Supply Oxygen rich blood directly to working heart muscles CoronarySinus major tributary deoxygenated blood from heart muscles receives working - , * identify heart Internal Anatomy (outside & chambers inside of in 4. Values · separate chambers ↓ exits of heart to prevent backflow sep. left I right atriums ↳ I ① Pulmonary! lings. - I ↳Contract for value ② - Sep. left d right ventricles. movement ↳ attached to tendinous cords Interparterial septum-separate right left atrium (O2 blood d non of blood separated) Fossa ovalis-remnant of an interatical opening , the foramen ovale , that has a significant role in Fetal circulation , but closes once baby reaches 6m -1y of age. ↳ blood allows to bypass pulmonary circulation in unborn babies Pectinate Muscles-in wals of left ↓ right atrium-develop powerfull contraction t pump blood from atrium # ventricles : for blood Opening coronary Sinus-drains deoxygenated directly to right atrium Valves = Discussed next pages : Papillary muscles - prevent reverse opening of Ar Valves (prevent backflow) Ligamentum Arteriosum = Nofunction in dus. In fetus , it connects pulmonary artery t art allowing blood Shunt away from pulmonary circulation Trabeculae Carneae- irregular muscles found in inner layers of centricles. May help with cardiac contractions & structure of ventricles. Interventricular septum - Separate left +right enticle. Pericardial Sac-Fibrous sac that encloses heart its vessels. Pericardial Cavity-space between serous layers of pericardial sac  Internal Anatomy · endo = in epi · = out myo · = muscle heart · inside of blood Thickest touching · ↳ · m= Middle · protective layer. Values * know both names ↓ lable or location * · values prevent backflow to ensure blood flow one-way Atrioventricular (AV) (left between right) Ventricle · values + - an atrium - right Ar value also called tricuspid · value · left Ar value also called bicuspid or mitral value semilunar value Pulmonary Semi-lunar value & aortic Semi-lunar value - · between ventricle t an atrial trunk.  Pulmonary & Systemic Circulation smallest. Pulmonary Circulation - Deoxygenated blood from right side of heart to langs. · at lungs , blood picks up oxygen+ release 102 · Blood Vessels return blood to left side of heart Largest Systemic Circulation - Oxygenated blood from left side of heart to systemic cells blood exchange · at systemic cells (e g.. Skin , muscles) , & wastes gases , nutrients , Blood blood to side of heart vessels return right ·. Basic Pattern : heart right Right heart > - lungs > - left heart - > systemic tissues - The Pericardium. · heart enclosed in 3 layers of tissue. · Fibrous pericardium Coutermost) - Dense Connective tissue · attaches to diaphragm + base of aorta & trunk pulmonary · parietal layer of serous pericardium - (middle layer · visceral layer of serous pericardium - (inner layer · 2 serous layers continuous with each other - separated by pericardial carity (contains serous fluid , acts as lubricant) · fibrous pericardium 2 parietal layer of serous pericardium together form. the pericardial sac. Pericarditis - inflammation of pericardium from Virus , bacteria , fungi ↳ fluid accumulation in Cavity.  Heart Sounds & Heart Mummers 4 normal heart sounds. · · 2 familiar sounds "lab-dub" - S1JS2 sounds , S1 close closing 10 values - open t · , of at same time S2 of Semilunar values - opent close closing same time. · , at · each value heard best at specific locations · Heart murmur : abnormal heart sound ↳ values not functioning or closing properly Result of turbulence of blood passing through heart · some medically important some not · , · Two types : valvular insufficiency valular stenosis. - Structure of Cardiac Muscles. involuntary · movement · Appears stricted , much like skeletal · contains endomysium , which surrounds t protects each muscle Fiber · T-tubules allow electrical impulses to penetrate deeper into Muscle Fiber (composed gap junctions ( · contain interculated discs of desmosomes & · interculated discs-linkages between adjacent cardiac muscle cells. They contain 2 specific structures ; : Desmosomes protein filaments that anchor into the Sarcolemmas (cell membrane of adjacent cardiac muscle cells to prevent them from pulling apart. Gap junctions : protein pores between adjacent cardia Provide for the flow of ions between for continuous action potentials muscle cells. low resistance Pathway cells  Metabolism Cardiac of Muscles. · High demand for energy · Extensive blood supply · numerous Mitochondria. Contain : Carries t · red Myoglobin protein , contains heme. stores Oxygen in muscle cells. similar to hemoglobin. · Contains Creatine Kinase : helps to catalyze the formation of ATP molecules - found in Cardia ( molecules , Skeletal muscles + brain. · Able to use different types of fuel molecules · fatty acids , glucose , lactic acid , amino acids , ↓ Ketone bodies · Relies mostly on aerobic metabolism. · makes it to failure when (O2 susceptible ischemic is low) Interference · w blood flow to heart can cause cell death.  Angina Pectoris & Myocardial Infarction · Atherosclerosis : Plaques narrow coronary artery Coronary Spasm : Sudden of Vessels · narrowing ↳ could be caused by drug effects , sudden cold , emotional stress. · Both above can lead to or myocardial infarction argina Pain. Angina pectoris : · usually on left side of Chest , left arm , or jaw ↳ referred pain when usually performing strenuous activity · treatments induce Vascular dilation Myocardial Infarction : heart attack complete occlusion of Suddent coronary artery · myocardium deprived of oxygen , possible tissue death · Excruciating chest pain down left arm (men) · weakness short of breath sweating , , nausea , anxiety ,. Innervation of the Heart Influences of heart rate : · Baroreceptors · chemoreceptors Sympathetic NS · · Parasympathetic NS Cardiac Center (medulla Oblongatal cardio-acceleratory Contain + cardio-inhibitory · centers · receive signals from baroreceptors + chemoreceptors in cardiovascular systems ↳ Baroreceptors : detect blood pressure ↳ chemoreceptors : detect blood 02/202 levels Send signals via sympathetic f parasympathetic pathways , · modifies (not initiate) cardiac activity that influences heart rate & force. Parasympathetic innervation decrease heart rate. starts at medulla's cardio-inhibitory · center relayed through vagus nerves (CNX) ↳ SA node. right vagus innervates ↳ left AU vagus nerve innervates node. · Affects heart rate , but not force because these nerve Fibers do not innervate the heart muscle tissue directly Sympathetic innervation - Increase heart rated force. start at medulla's Center Cardio-acceleratory · relayed through neurons from T-TS segments of spinal cord ↳ extend to SA node. Al node , myocardium t , coronary arteries increases vessel dialation coronary · increase heart rate& force The Hearts Conduction System Conduction system : initiates & conducts electrical events to ensure of contractions proper timing composed specialized that but do not contract of Cardiac muscle cells have action potentials activity influenced b autonomic NS Parts of hearts ConductionSystem : * Sinoatrial (SA) Node hearts Pacemaker # E - located high posterior of · in wall right atrium u Atrioventricular (AU) node-located on floor of right atrium (near right AU value) ↳ Atrioventricular (Ar) bundle Av node I - Extends from through interventricular septum Divides into left & right bundles ·. Purkinje fibers - extend from left& right bundles at hearts apex · through walls of ventricles.  * A order of activation 1. 2 : 3 - 4. ↳ end contractions Stimulation of the Heart · Heart contraction has 2 events : · the conduction system initiates & propagates action potential Cardiac ~ muscle cells fire action potentials & Contract  * 3 Phases Action Potential of Cardiac Muscle Cell. Electrical of Cardiac muscle · events action potential 1. Depolarization impulse from system (or gap junctions) opens fast Voltage-gated · conduction Nat channels Nat membrane potential from 90mV to + 30m enters cell changing Nat channels Voltage-gated start to inactivate · 2. Plateau · Depolarization opens Voltage-gated +I slow Voltage-gated cat channels · K+ leaves Cardiac Muscle Cell as Catt enters ) ↳ stimulates sarcoplasmic reticulum to release more (aft ↳ membrane remains depolarized. 3 Repolarization cast channels close while It channels voltage-gated remain open · · membrane potential goes back to 90m Cardiac Muscle cannot exhibit tetary have unlike Skeletal muscle , Cardiac cells a long refractory period · cell cannot fire impulse during refractory period · a new plateau refractory period · to of about 2Som cardiac muscle cells phase leads heart cell contracts & relaxes before it can be stimulated again makes Sustained (tetanic) Contraction impossible. ·  Electrocardiogram · EGG/EKG Skin electrodes detect Signals of cardiac cells · muscle Common tool diagnostic · composed of waves diagnostic · multiple segments that can provide Valuable information about heart conduction. P wave Reflects SA node. changes of atrial depolarization · electrical originating in - ↳ depolarization = Contracting · QRS Complex - electrical changes associated with ventricular depolarization atria · also simultaneously repolarizing. T electrical wave change associated with ventricular repolarization · - ↳ repolarize relaxing =. I between correspond to plateau phases of cardiac · segments waves action potentials (no electric change) PQ Segment-associated with atrial Cells Plateau Catria are contracting · · S-T Segment Associated with ventricular plateau (ventricles contracting) - are The Cardiac Cycle Cardiac Cycle : includes both systole (contraction)& diastole (relaxation ( ventricular activity most important driving force. · is ~ Systole-Ventricular Contraction raises Ventricular pressure · Ar values pushed closed Semilunar pushed opena blood ↓ into · values ejected to artery pulmonary systemic Circulation Diastole-Ventricular pressure · relaxation lowers Ventricular Semilunar values · close kno pressure from below keeping them open.  · AV values open-ventricles fill with blood ↳ them pressure closed no pushing Cycle Phases of the Cardiac As the cardiac cycle begins · ↳ 4 chambers blood at rest , returning to both atria , passive filling of Ventricles, At values open ↳ Atrial pressure) ventricular pressure Semilunat values closed ~ ↳ pressure in Ventricles /Arterial trunk pressure. Atrial Contraction & Ventricular Filling Atria Contract blood pushing remaining · into ventricles · ventricles filled to end-diastolic volume (EDV) · Atria relax for remainder of cardiac cycle Isovolumetric Contraction · ventricles contract , pressure rises & AV values are pushed closed , · ventricular pressure is still less than arterial trunk pressure , so semilunar values still closed ventricles above arterial pressure. · continue to contract so that ventricular pressure rises Ventricular Ejection · Semi-lunar values forced open as blood moves from ventricles to arterial trunks stroke volume (SU) is amount of blood ejected by Ventricle ~ End Systemic Volume (ESV) is amount of blood remaining in ventricle after contraction finishes ↳ ESU = EDU-SV ; Eg. domL = BOmL-TOmL Isovolumetric relaxation ventricles & Start relax to expand lowering pressure · , arterial Pressure greater · than ventricular pressure By Sliding back toward blood · ventricles , closes semilunar values · AU values remain closed · When all values are closed , blood neither enters nor leaves f the time is called isovolumetric Atrial relaxation & Ventricular filling all heart chambers are relaxed · atrial blood pressure forces Ar values opena blood flows into ventricles · Semilunar values remain closedSince arterial pressure than Ventricular pressure is greater Cardiac Output of blood 1 minute amount pumped by a mingle Ventricle · in ↳ measured in liters per minute · measures of effectiveness of Cardiovascular system Increases healthy individuals during exercise · in · Determined by heart rate /beats per minute) + stroke volume (amount of blood ejected per beat · HRXSV = Co ↳ TS beats/min X TomL/beat = 5. 25 L/min * calc. Stroke Volume  Variables That Influence Heart Rate Positive Chronotopic Agents (increase heart rate ↳ Chrono = heart rate. · Thyroid hormone ↳ Increase number of B2-adrenergic receptors on modal cells. · Caffeine ↳ breakdown inhibits of CAMP · Nicotine ↳ increase release of norepinephrine ~ cocaine ↳ inhibits reuptake of norepinephrine Negative Chronotropic agents (decrease heart rate parasympathetic activity · · Beta blocker drugs ↳ interphere with epinephrine t norepine