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45 Cards in this Set
- Front
- Back
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In the CV system, what affect occurs as a result of the Cerebral, Coronary, Renal, GI, Skeletal and Skin systems being in paralell configuration?
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Resistance is reduced, thus you have a reduced pressure system.
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The cerebral blood volume requirement is between 15-20%. why is it so large/
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Brain has no capacity for storage of O2 or glucose, it is an obligate user.
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Why does renal system need 25% vblood volume?
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It needs a large volume ob blood/ and pressure to maintain its filter ability.
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Why does skeletal need so much?
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Fight/ or Flight
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Why does coronary system only need 5%?
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It has a large volume reserve, so it can take O2 easily.
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What type of CV injury causes shearing?
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acel/decel injury--MVC
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Where does the injury most often occur?
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Ductus Arteriosus--small ligament
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What vessels in CV system have the greatest resistance/ why?
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Arterioles, small diameter
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why does right side of heart have thin walls?
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low pressure system to lungs
7 in RA 25 in PA |
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Why does left sideof heart have high pressures, and thicker muscle?
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Increased work load to pump out CO against resistance to aorta- which also has a 90 degree turn to distribute blood
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Where is a common area of infarct in coronay vasculature?
arythmia? |
LAD which supplies septum and Left ventircle on ant. wall
Rt bundle block |
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A clot at the L. main coroany artery results in?
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lethal infarct- lack of supply to entire heart and septum
R bundle block |
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Infarct to LCX?
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Lat wall, SA node 50%, AV 10%, left atrium
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RCA?
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Inf/post walls, SA node 50%, AV 90%, RV, R Atrium
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Explain Sympathetic innervation of CV?
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Thoracic cord to Atriai and Ventricles send message via blood stream: Norepi to beta 1 receptors: in crease contractitliy(inotropic) and rythm. Epi to Beta2 reeceptors: coronary dilation Norepi to Alpha1: coronary constriction
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Explain parasympathetic innervation.
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From medulla via Vagus to S AV nodes aliitle to SA. Chemical: ACH Function: target rate only not strength of contraction ( only few messengers to SA)- reduce pumping 50%
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How much can sympathetic stimulation affect CO?
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almost 4 times increase
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What is path of electrical conduction?
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SA node to internodal pathways,
to AV node, to Bundle of HIS to Rt & lt bundles to Purkinje fibers to intercalated discs to cell to cell |
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What kind of communication occurrs between myocytes?
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gap junction- very fast
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Whatis another name for the electrical system of heart?
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Excitation
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What is another name for cardiac output? CO
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Forward flow
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What is required to get fwd flow?
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A chang e in pressure for rt side to left side
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whatis the greatest determinant of fwd flow/
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radius of vessel to the 4th degree
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What is one way heart can compensate to change flow?
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It can vasodilate and change pressure and thus change flow
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Flow is directly proportional to ...?
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pressure and radius
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Flow is indirectly proportional to...?
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Length and viscosity
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Give 4 examples:
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1. increase pressure = increase flow unless tapped out
2. Vasoconstriction = decrease radius = decrease flow unless heart works harderor radius increase = increasB/P 3. Longer length of vessel = increase resistance = decrease flow 4. increase viscosity= increase resistance= decrese flow unless heart works harder to maintain flow |
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Formula for flow
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chg pressure X pie radius to 4th over 8n X length X viscosity
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Why are alveolar/capillaries a low pressure system?
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In parallet configuration and very thin walls - multiple channels for run off- have decresed resistance
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What occurrs when Volume is decreased?
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Vasoconstriction, decrease flow to gut and skin shunt to vitals
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What occurrs when B/P decreased?
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vasoconstrict= increase flow( increased velocity)= increase pressure
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Whatis laminar flow?
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A parabolic flow itis smooth and straight the edges of the vessels have some resistance and shearing the center most RBC slip by the easiest. Pattern occurrs in a normal vessels
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What kind of blood flow occuurs with decreased b/p?
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Laminar flow, will slow flow, requires less energy
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What function does endolthelium provide?
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It produces heparin which prevenst sticking of those slow moving RBC in laminar flow; considered an organ. result no clotting
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What are the characteristics of turbulent flow?
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requires more energy. ther ismore resistance and takes increased pressure to get flow. result of damage in vessel, no shear force disorganized flow.
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Why can yuo feel a bruit?
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Itis turbulent flow. Dialysis pts with AV shunt have.
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Name 4 determinants to forward flow/ CO?
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HR, Afterload, Preload and contractility
CO=HR X SV if any go bad Co affected |
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Relationships to decreased SV?
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Increase HR, but less filling time so SV decreases
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What is an inotropic affect?
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something that increase the strength or squeeze of contraction
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What endogenous biological chemical affects CNs and CV?
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catecholamine
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At what point does increased HR not produce increased CO?
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100 bpm
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Explain mechanism of increased HR d/t fever?
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Increase HR, increased metabolism d/t acidotic state, increase energy= increased heat
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How do ions affect HR?
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Excess K+ can block conduction = decreased HR
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How does over distended heart affect HR?
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Suppress vagus= HR decrease called Bainbridge affect
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Whatis conatropic?
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?
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