Lecture 11.0 – Cardiovascular System - PowerPoint Presentation

Lecture 11.0 – Cardiovascular System Genalin Lagman TaguiamLecturer

Course OutcomesOn completion of the week’s activity, the students should be able toidentify the structures in a given diagram of the heart;name the major blood vessels that supply blood to the myocardium and that return deoxygenated blood to the right atrium;trace the pathway of blood flow through the heart;describe the components and function/s of the conduction system of the heart;

describe the various phases of the cardiac cycle;relate the heart sounds heard with a stethoscope with the cardiac cycle;define cardiac output; list the factors that affect cardiac output.differentiate between arteries, veins and capillaries, in terms of structure and functions;Course Outcomes

Course Outcomesdistinguish between systolic pressure, diastolic pressure and pulse pressure;state the factors that affect blood pressure;describe the neural control of blood pressure.trace the pathway of circulation in (a) the systemic circulation, (b) the pulmonary circulation, (c) the hepatic portal circulation, and (d) the fetal circulation;name the major arteries and veins of the systemic circulation.

Cardiovascular SystemDelivers oxygenated blood to tissues and removes wastes productsComposed of the:composed of the heart, blood, and the blood vessels

Heartabout the size of a clenched fistlocated obliquely within the mediastinum of the thoraxPointed apex is directed anteriorly, inferiorly and to the leftBroad base is directed posteriorly, superiorly and to the right

Heartenclosed within a double sac made up of the outer fibrous pericardium andthe inner serous pericardium (parietal and visceral layers)EpicardiumPericardial fluidThin film of serous fluid between the parietal and visceral layersReduces friction between the layers as the heart moves

Layers of the HeartEndocardiumInnermost layerProvides smooth lining for the chambermyocardium (reinforced by a fibrous skeleton) Middle layerCardiac muscle tissueepicardium (visceral layer of the serous pericardium)Outermost layer

Chambers of the Heart

Function of the Cardiovascular Systemincludes structures in the body that play important role in maintaining:adequate and unidirectional, forward blood flow to controloxygen delivery

functionally, a double pumpright heart receives blood from superior vena cava, inferior vena cava, and coronary sinus (vein that collects blood from the coronary circulation)pulmonary circuit pump: oxygen-poor systemic blood enters the right atrium, passes into the right ventricle, through the pulmonary artery/pulmonary trunk to the lungs, and back to the left atrium via the pulmonary veinsFunction of the Cardiovascular System

left heartreceives blood from the four pulmonary veins through the left atriumsystemic circuit pump:oxygen-rich blood entering the left atrium from the lungs flows into the left ventricle and then into the aorta, which provides the functional supply of all body organsFunction of the Cardiovascular System

has right and left coronary arteries that branch from the aorta and via their main supply oxygenated blood to the heart itselfvenous blood, collected by the cardiac veins (great, middle, and small), is emptied into the coronary sinus that return deoxygenated blood to the right atriumBlood supply to the heart muscles

Valveskeep the blood flowing in only one direction through the heartatrioventricular (AV) valves: tricuspid and mitralprevent backflow into the atria when the ventricles are contracting (during systole)semilunar (SL) valves: pulmonary and aortic valvesprevent backflow into the ventricles when the ventricles are relaxing (during diastole)

ValvesChordae tendinaeheart stringscord-like tendons that connect the papillary muscles to the tricuspid valve and the mitral valve in the heartprevent eversion, prolapse, by becoming tense thus pulling the flaps, holding them in closed position.

produces normal heart sounds that arise chiefly from turbulent blood flow during the closing of heart valvesHeart

network of specialized (autorhythmic) cardiac muscle fibers that provide a path for each cycle of cardiac excitation to progress through the heartensures that the chambers of the heart contract in a coordinated manner (each area of conduction normally happens before the actual mechanical activities of the heart)recorded as electrocardiogram (ECG/EKG)Conduction System of the Heart

Conduction System of the Heart sinoatrial (SA) Located at the right atriumPacemaker of the heartinitiates an action potential (AP) 100 times in every minute (faster than any other cardiac muscle fibers)stimulate other conduction areas before the other areas are able to generate an AP at their own slower rate

Conduction System of the Heart atrioventricular (AV) node located in the septum between the right and left atriaAV bundle (bundle of His)only site where APs can conduct from the atria to the ventricles

Conduction System of the Heart right and left bundle branchesextend through the interventricular septum toward the apex of the heartPurkinje fibersconduct the AP from the apex upward to the remainder of the myocardium

Innervation by the Autonomic Nervous Systemcardiac centers in the medulla include:cardio-acceleratory center, which projects to the 1st to 5th thoracic (T1–T5 ) region of the spinal cord, which in turn projects to the cervical and upper thoracic sympathetic trunk cardio-inhibitory center exerts its influence via the parasympathetic vagus nerves (cranial nerve X), which project to the heart wall

Cardiac Cycleconsists of events occurring during one heartbeatduring mid-to-late diastoleBlood flow passively from atria to ventriclesSL valves closed, AV valves openAtria contract forcing remaining blood into the ventricles

Cardiac Cycleventricular systole consists of the isovolumetric contraction phase and the ventricular ejection phasePressure within the ventricles increasesAV valves are closedSL valves are openAtria are relaxed

Cardiac Cycleearly diastolethe ventricles are relaxed and are closed chambers until increasing atrial pressure forces the AV valves to open and the cycle begins again

amount of blood pumped out by each ventricle in 1 minute typically amounts to 5,000 mL/minbasic formula:CO = heart rate (HR) × stroke volume (SV)Cardiac Output (CO)

Heart Ratenumber of heart beat in full minuteNormal range: 60-100 bpm affected by the activation of sympathetic nervous system increases heart rate and contractilityparasympathetic activation decreases heart rate but has little effect on contractility

other factors influencing HR are:age: HR decreases as age increasesgender: after puberty, the average male’s HR is slightly lower than the female’sstate of activity: activity increases the HRbody temperature: peripheral vasodilation & increased metabolic rate increase the HRHeart Rate

Pulserhythmical throbbing of arteries produced by the regular contractions of the heartPulse deficita condition in which a peripheral pulse rate is less than the ventricular contraction rate indicates lack of peripheral perfusion.

Stroke VolumeAmount of blood ejected per heart beatApproximately 70 mlDetermined by three factorsPreloadAfterloadcontractility

Vascular Systemnetwork of arteries, arterioles, capillaries, venules and veinsConstantly filled with 5 L of bloodArteriesCarry blood away from the heartVeinsCarry blood towards the heartCapillariescarry blood to tissues and are gas exchange sites

Blood Pressureforce per unit area exerted on a vessel wall by the contained bloodpeaks during systole (systolic pressure)during diastole, as blood is forced distally in the circulation by the rebound of elastic arteries, arterial BP drops to its lowest value (diastolic pressure)

routinely measured by the auscultatory (listening) methodnormal blood pressure in adults is 120/80 (systolic BP/diastolic BP)varies directly with CO, peripheral resistance (R), and blood volume(BV):as CO/R/BV increases, BP also increasevessel diameter is the major factor determining resistance, and small changes in vessel (chiefly arteriolar) diameter significantly affect blood pressureBlood Pressure

Blood Pressureregulated by autonomic neural reflexes involving:baroreceptors or chemoreceptorsvasomotor center (a medullary center that regulates blood vessel diameter)sympathetic vasomotor fibers, which act on vascular smooth muscle

Fetal CirculationDependent on maternal circulation for oxygenationDelivers oxygenated blood to major organsPresence of three major shuntsDuctus venosusForamen ovaleDuctus arteriosus

Hepatic Portal CirculationVeins of hepatic portal circulationDrain the digestive organs, spleen and pancreas and delivers this blood to the liver through the hepatic portal veinLiver is drained by the hepatic veins that enter the inferior vena cava

ReferencesMarieb, E.N. (2010). Human anatomy and physiology (8th Ed.). San Francisco, Pearson.Marieb, E.N. (2006). Human anatomy and physiology (7th Ed.). San Francisco, Pearson.Tortora, G. J. (2006). Principles of anatomy and physiology. (11th. Ed.). New Jersey, John Wiley and Sons, Inc.