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Cardiovascular System Functions: Generate__________ __________ Routes _________ Regulates ________ and _________ of blood flow A muscular pump and network of vessels to distribute blood to ENTIRE body 15.2 Heart Anatomy Base: to apex: ~ 14cm Describe the location of heart. What is the name of this Anatomical region? Membranes double-walled sac = 1) outer layer, tough, dense connective = _________ -protects, anchors and prevents overfilling 2) inner, 2-layered = _________ _________and _________ ___________ aka epicardium Between the 2 layers of serous is cavity with serous fluid = pericardial fluid Wall of Heart 3 layers: 1) Outer epithelial & connective = ________ 2) Middle cardiac muscle = ____________ 3) Innermost epithelial & connective is continuous with vessels = _____________ Chambers & Landmarks Superior = _______ = RECEIVERS of blood, has auricles WHAT are the vessels that deliver? Divisions = ________ and _______; sulces on surface only Inferior = ________ right one is most of ant. surface, left one is inferoposterior surface and is the ______. Ventricles form and function Bulk of heart: they are ________ due to pressure generated when muscles _________. Interior: irregular bundles of muscle = trabeculae carneae Chordae tendinae: papillary muscle: When contraction: right ventricle sends blood to = and left ventricle sends blood to = Atrioventricular (A-V) valves prevent backflow into atria when ventricles contract Right valve = left = Heart relaxes = VALVES ________. Blood enters atria and passively flows into ventricles. Heart contracts = VALVES ________. Semilunar valves: Named for vessels (pulmonary & aorta) and appearance As ventricles contract, pressure is ________ in the ventricles than the vessels they serve…VALVES ______. Blood rushes into vessels, as soon as pressure is _________ in vessels…VALVES __________. Fibrous skeleton of heart • Elastin and collagen, thicker around heart valves and where great vessels leave heart • Reinforces the myocardium, ________ & ________valves • Also INSULATES to prevent electrical stimulation. How does blood move through heart? 2 pumps that have separate circuits PULMONARY=Right side SYSTEMIC =Left side • Blood returns to right atrium, O2 poor and CO2 rich (what vessels?) • Blood flows from atrium to ventricle (valve?) • From right ventricle leaves via pulmonary artery (valve?) • gas exchange occurs in ______ • blood from lungs to left atrium (what vessels?) • passes into left ventricle (valve?) • leaves through aorta (valve?) • ALL tissues of body Compare and contrast Equal volumes moved by each side BUT ____________ = less mileage and lower pressure system (24 and 8 mmHg) ____________ = 5 times more resistance (friction) much longer and high pressure (120 and 80 mmHg) How does this affect appearance? Coronary circuit Heart is large muscle VERY metabolically active, needs own supply of oxygen and nutrients Lots of individual variation and collateral circulation…WHY? 15.3 Heart Action Initiation & perpetuation of cardiac cycle = blood flow through heart from contraction to contraction driven by __________. _______ are primer pumps = fill ventricles with blood __________ are power pumps = move blood to body Blood moves out of chambers during _________ also known as _________ and into chambers during ___________ also known as ___________. Ventricular filling: diastole Blood returning to heart AV valves are______, SL valves are _________ • Pressure in ventricle is _________than atria • 70% of ventricular filling will occur passively • Atrial systole: delivers 30% of blood. Ventricular systole Atria relax = atrial ________ Ventricles begin contraction, pressure rises as soon as it is _______ atria AV valves will ___________. As soon as pressure in ventricles > vessels, SL valves _______ and ventricular ejection occurs Understand cause and effect….. Your health is dependent on ________ ________. Blood flow is controlled by ________and ______of valves. Valves are controlled by _________. Pressure changes are result of __________ and ________ of myocytes/muscle. Let’s add the sound effects to this…..Heart sounds • Lubb-dupp = closing of valves and slowing of blood flow. • Lubb = ________valves, beginning of ________ as ventricular pressure rises • Dupp = _________valves, beginning of ventricular _________. Heart murmurs -valve problem If incompetent valve, hear swishing as the blood regurgitates through valve, after closes If stenotic valve, high pitched sound or click due to restricted flow through the valve, before closes Workload increases and over time weakens heart So what “drives” these pressure changes? Cardiac conduction system: Noncontractile cells to initiate and distribute the impulses/action potential (assisted by the gap junctions) NAME the 6 components. How do you get started? Right atria, inferior to S.V.C. Spontaneous due to decrease in K+ and increase in Ca++ and Na+ permeability Inferior portion of interatrial septum above tricuspid valve Generates impulses ~ 75/minute (rate in the absence of neural and hormonal factors is 100) ONLY electrical connection between atria and ventricles (insulated by fibrous skeleton) Sets the pace since it is fastest Impulse is delayed here to let atria respond and contract due to smaller fibers and fewer gap junctions. Moving into the septum & through the ventricles aka bundle of His Superior part of interventricular septum Divide into the right and left branch….These serve the respective ventricles Responsible for the bulk of ventricular depolarization Course along septum toward the apex Rapid conduction, which allows ventricular muscle to contract simultaneously How do we measure this? Electrocardiogram (ECG or EKG) • Composite of all APs generated by nodal and contractile cells through time • Measures electrical activity from surface of body (12 leads system) 3 discernable waves, Name them. Depolarization Waves • P wave = ________ _______ from SA node through atria, 0.1 sec after P wave begins, atria _________. • QRS = __________ ________ shape reflects the change in paths….leads to contraction The heart must “reset” ____________ = ventricular repolarization, this marks the ___________AND the inability to respond to another AP (refractory period) Atrial repolarization occurs during ventricular depolarization As blood rebounds off the closed valves get spike in pressure = dicrotic notch Needs change….how do you regulate? Heart rate: affected by___________(vagus nerve) &____________(accelerato r nerve) _________stimulation dominates at rest When either system is stimulated the other is _________. Medulla to SA and AV nodes. Baroreceptor reflex Changes in blood pressure affect the amount of stretch in the vessel walls of aorta and carotids Sensory = Integrator/Coordinator = Response = (activate P.S.) = (activating sympathetic) Other influences on regulation Name 4 other things that can influence Heart Rate. 15.4 Blood Vessels So now you know what blood does (and what is in it) You know what moves it BUT…how does it get to the cells? Leaving the heart = _______, they branch/diverge as get smaller become __________. Arterioles become __________ smallest diameter = exchange Going back to _______ = capillaries become _________join/converge as get larger = _______. Structure: 3 tunics Innermost called _______ or ________ : endothelium =simple squamous The middle is _______: smooth muscle = bulk, controlled by ANS =vasomotor control The outermost is _________or __________: connective tissue = collagen, anchors amount & type of tissue determines and protects vessel and its function Arteries: leave heart & deliver blood • Elastic: Most elastin (in ALL 3 layers) more elastin than muscle,allows expansion and contraction/recoil with pressure and volume fluxes • muscular/distributing :media-mostly smooth muscle, more active in vasoconstriction & vasodilation= ability to control blood pressure and flow Arterioles become metarteriole __________ directly controls what capillary beds get perfused, large ones have 3 layers…. But as get close to capillaries have ONLY __________& bands of _______ _________. What controls SM contraction? Control of blood flow through capillary beds 1) ___________ ___________ aka. metarteriole-thoroughfare channel, short vessel that directly connects the arteriole and venule = BYPASS 2) __________ _________ (smooth muscle fiber) acts as valve to regulate flow into bed Bed can be flooded or completely bypassed depending on need of tissue or organ Capillaries = EXCHANGE • Only _______ ________ …designed for exchange! Permeability varies from tissue to tissue: in muscle = ______; in kidney, endocrine, intestines = ________; in bone marrow, liver, spleen = ___________ NONE in cartilage, epithelia, lens and cornea LOTS in skeletal, cardiac lungs, kidneys Correlates with metabolic activity Hydrostatic Pressure: Drives fluids _____ of blood via filtration Colloidal Osmotic pressure (OP): ______ hydrostatic pressure KEEP water(fluid) ___ capillary. Net pressure determines movement of fluids Fluid leaves the capillary if the HP is ______ _______OP and enters the capillary if the OP is ______ ______ HP What happens to excess fluid? Note if pressures change SO does the movement of fluid Venules: going back to heart • 10 – 100 mm • Look a lot like capillaries • Postcapillary venules = endothelium and connective tissue • Somewhat porous & permeable veins 3 distinct tunics : BUT always _______ walls • Tunica ______ is thin and poorly developed • Tunica ________ is thickest with collagen and elastin = highly distensible • Larger __________ Venous blood pressure Steady with VERY little change (little resistance here, BIG lumens) Dissipates from ~20 mmHg to nearly 0 mmHg at vena cavae So how do we get it to heart? Valves & “pumps” DESCRIBE THESE 15.5 Blood pressure (mm Hg) Force per unit area exerted on a vessel wall by the contained blood Greatest force in the largest arteries near heart (systemic arterial BP) due to __________________. 1) How much vessels can be stretched (compliance) 2) Volume of blood forced into them Pulsatile since amount of blood entering & leaving fluxes constantly What happens in systole? What is diastole? You can feel this = pulse Difference between systolic and diastolic = expansion and recoil of arteries Anywhere in arterial tree that can be compressed against firm tissue = pulse points Factors that influence blood pressure: 1)Heart action= stroke volume (SV), heart rate (HR), 2) vessel characteristics = resistance 3) blood characteristics = viscosity & volume So heart imparts pressure and vessels work to maintain this without being damaged the goal is maintaining BLOOD FLOW Heart Action = cardiac output (C.O.) • Amount of blood pumped out of each ventricle in 1 minute • DEPENDS ON ________ ___________= volume of blood pumped out by one ventricle in a “beat” generally related to force of contraction ________ ______= contractions per minute What is the math formula for cardiac output? What’s this got to do with pressure? • Blood pressure varies _______ with cardiac output • SV increases or HR increases = ________ in blood pressure • SV decreases or HR decreases = ________ in pressure Blood Volume • Usually ~ 5 to 6 L (8% of mass) varies with age, size and sex • Pressure is __________ related to the volume (think about water faucet, turn up flow what happens) • Loss of blood = ________ pressure Resistance (peripheral) = P.R. • This is the friction between the blood and the vessel wall. • If friction increases what happens to flow? So what must blood pressure do to re-establish flow? MOST important factor: ___________ of the vessel vasoconstriction or vasodilation will alter BP!!! Viscosity • Ease of the movement of molecules in a solution In blood this is due to amount of what? • So increase in viscosity will __________ friction/resistance and what would the pressure need to do to re-establish flow? • Do you remember what we call an increase in rbcs? How about a decrease? So let’s look at this relationship…. • Blood pressure (B.P.) is the result of 1) C.O. which is S.V. & H.R. AND 2) P.R. • B.P. = C.O. (amount of blood leaving heart over period of time) “X” the P.R. (the forces that slow or speed up movement = size of vessel and viscosity of blood) S.V. and H.R, ultimately are affected by….NEURAL, CHEMICAL & MECHANICAL What is the mathematical formula to determine stroke volume? ( blood collected - blood left behind after contraction) ____ ______ ______depends on how long diastole lasts and venous pressure = PRELOAD ____ ________ _________depends on arterial blood pressure = AFTERLOAD and force of ventricular contraction =CONTRACTILITY Preload: degree of stretch on heart • How much are myocytes stretched BEFORE contraction (mechanical) is due to ________ ________. While resting SkM are kept near optimal length for developing tension, cardiomyocytes are shorter Can also increase venous return with increase sympathetic stimulation (recall venous reserves, fig 15.32) Venous Pressure • If LOW, sympathetic can stimulate VSM to contract/constrict which increases venous return, • Systemic venous blood returns to which chamber? =central venous pressure If heart beats weakly then blood remains in heart and the pressure increases, which decreases venous return affecting heart’s function and can lead to peripheral edema Venous return more blood returns = more stretch = _____ _________ = more contraction = more ______ __________ = more cardiac output This is the Frank Starling law of the heart • Slow heart rate, or exercise increase cardiac output making heart more efficient Contractility • Increase in contractile strength (at a given preload) due to Ca++ influx into cytoplasm of myocytes • Affected by neural (ANS) and chemical (epi/norepi & T.H.) • As increases, eject ______ blood from heart = __________ ESV and increase SV. Afterload: back pressure • Pressure in vessels that must be overcome for ventricles to eject blood, through S.L. valve (80mmHg in aorta, 8 mmHg in pulmonary) • DO you see WHY Hypertension reduces blood leaving heart? It __________ESV and decreases SV Heart MUST work harder to move blood Vasomotor Center = P.R. • This in conjunction with cardiac center = cardiovascular center in medulla • Functions to alter cardiac output AND _______ ___________ • Uses __________ (efferent) nerves, transmits nearly constantly = constant moderate constriction or vasomotor tone in vessels Vasomotor tone • Varies from organ to organ…skin and digestive are normally more constricted • Any increase in sympathetic activity will _______ vasoconstriction (skin & viscera = increasing MAP) = important regulator of blood pressure (organ) So moment to moment regulation Cardioinhibitor reflex In opposite circumstances = cardioaccelerator And the vasomotor center contributes Local control of blood flow How tissues and organs control flow to meet their needs, Metabolic, neural, hormonal, longterm Tissue Perfusion 1) Delivery of O2 and nutrients and Removal of waste 2) Gas exchange in lungs 3) Absorption of nutrients from digestive tract 4) Urine formation Rate of blood flow needs to be precisely what the tissue/organs need to fulfill this Local regulation of Flow Autoregulation: automatic adjustment to the local needs of tissue done via metabolite monitoring • Inadequate perfusion = decrease _____ and ___________= decrease metabolic activity which can lead to __________. • What can happen if too much perfusion? Mechanisms • By varying the resistance of arterioles, control blood into capillary beds via ___________ _______________ (also angiogenesis for long-term) • While the mean arterial pressure (MAP) is relatively constant (homeostasis), blood flow in organ is controlled intrinsically Metabolic controls • Decline in ____________ • Presence of __________, ___________ ____________, e.g, histamines and kinins, and ____________,e.g, K+, H+, adenosine, lactic acid, CO2 Causes vasodilation and relaxation of precap. sphincters Neural controls of vessels • MOSTLY affect the peripheral resistance due to ____________ division (innervate most blood vessels EXCEPT capillaries and precap sphincters which have no nerves) • Goals? Why do you need to do this?