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Cardio System-Notes - Heart fiinctions as 2 crusader pumps...

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Unformatted text preview: Heart - fiinctions as 2 crusader pumps lat pump = right side, pumps deoxvgenated blood to lungs v 2nd pump = left side, pumps oxygenated blood to builtr L Floatr of blood through heart: A. Pulmonary circulation: l. body-u} inferior and superior vena cavau} right atrium 2. right atrium-J tricuspid valve-J right ventricle 3. right ventricle—3' ptflmcnary semilunar valve-4' [:Iulrnortarjlr artery- J lungs Systemic circulation: 1. human} pulmonaryr veins—1" left atrium 2. left atrium-~33" bicuspid valve {mitral valvejl-é" left ventricle 3. left ventricle-J- aortic scmiltmar valve—3* certain} b-tnzl},I Difference between pulmonary and systemic circulation: - 1. blood leaving left ventricle {systemic circulation) must overcome great pressore blood leaving right ventricle {wlmonarv circulation) requires less effort to pump 2. left ventricle larger than right ventricle in order to eject blood f‘rciretefillljar 3. left ventricle: 30% ofmass of heart {right ventricle = Ill-15% of mass; atria = 540% of mass] 25 IL Bepolarieation ol‘ heart: - depolarization stimulates contraction of chambers and "pump" action A SA node: sinoatriai node i. found in right atrium 2. "pacemaker"; has the fastest intrinsic rate of beating so determines rate for other cells - rate transmitted to other cells by intercalated discs - inter-calated discs hold cells together by desrnosornes, so beat as "one" - also propagate action potentials through gapjunctions 3. Simultaneously transmits depolarization to left atrium and AV node: - SA"? bundle ot‘lEiacchn1an—2r left atrium ' Stir—3' internodal tracts—re AV node B. AV node: atrioventricular node 1. found between the atria and ventricles 2. depolarization slows here - because AV node cells beat intrinsically slower - also AV node surrounded by valves and fibrous skeleton of heart, this tissue does not conduct electrical impulses well . slowing necessary to allow atria to complete contraction, and eject blood into relaxed ventricles C. Ventricles: 1. AV node»:- Bundlc of His (though septum}—:‘* Purkirrie fibers _ (turn into ventricles at apex) 2. Spreads to papillaryr muscles - muscles attached to tricuspid and bicuspid valves by chenille tendinae - prevent tril'bi valves from flapping into atria when pressure builds in the contracting ventricle - leaky valves create inefficient pumping healthy valves maintain unidirectional flow of blood 1H. Cardiac cycle: . éescribes pressure relationships of heart chambers and flow of blood pressure increases by contracting a closed chamber A‘ "Rules" to keep in mind: .V‘fifwb’r- cardiac cycle uses the left ventricle as éts reference chamber only one valve can be open at a given time in the ventricle valves are one-way (open only due to pressure changes) blood flows from high pressure to law pressure P'we pressnre in atria Pym pressure in ventricles PA= pressure in aorta Filling..." Pa>Pv, PA>Pv I. left atrium empties into lefi vemricie (to FILL left ventricle) 2. therefore la: high pressure, iv“: low pressure, Pa>Pv 3. biwspid valve must be open semilunar valve closed 4, bicod not flowing into aorta, PA>Pv Isovolumetric contraction... Pn<Pv, PAPIW isovolumetric= same volume, blood not moving in or out therefore both valves closed considering valves are one way, these are only pressure relationships possible first heart sound {lubb) heard at start of this phase : turbulence as trifbivalves close Ejection... I’KPV, PA<Pv 1. blood ejected from lefi ventricie to aorta 2. therefore lv== high pressure, A: 20w pressm‘e 3. aonic semilunar vaive open bicuspid valve closed Isovalumctric «fixation... 1"a<II"v.r PA>P¥ 1‘ same conditions as isovoiumetric contraction 2. second heart soqu (dubb') as semilunar valves close Heart and Circulatory System - Heart and Circulatory System: heart-JMeries—b'capillariesuhveins - Vessel structure: o Tunlea eaterua: outermost layer, fibrous and collagen tissue e Tuniea media: middle layer, concentric sheets of smooth made a Tunica interns: innermost layer I. Arteries: any blood "A“way from heart - typically carry oxygenated blood, except for pulmonary artery (leaves RV) A. Characteristics of arteries: 1. thicker walls than veins . have a greater tunica media 2. more resilient than veins - more smooth muscle and elastic fibers 3. smaller lumen than veins B. Elastic arteries1| Muscular arteries, Arlu‘iules: i. elastic arteries - large vessels with lots ot‘elastin - diameters up to 2.5 cm - aorta and other arteries close to heart - Windltessel efl’eet: - distension of aorta when blood is ejected item the LV - aorta recoils and smoothes out pressure and blood flaw - helps perfiise coronary attenes by pushing hlcod hack to opening ofcoronaiyarteriee ( hidden by open semiiunar valve) 2. muscular arteries I medium sized arteries - distribute blood to muscle and organs - tnnica media has a lot of smooth muscle 29 arterioles - are called the resistance vessels - diameter ofthese vessels changes causing resistance to blood flow to change ...
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