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The flashcards below were created by user
arimoses
on FreezingBlue Flashcards.
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Why must flow be equal in the two circuits of the body (systemic and pulmonary)?
Because they are connected in series by left and right heart.
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What is the approximate pressure in the R ventricle, pulmonary artery, L atrium, Capillaries?
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What is the approximate pressure in the L ventricle, Aorta, Mean Art. BP, R atrium?
- 120/0
- 120/80
- 93
- 0 (Central Venous pressure).
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What maintains higher pressure in the systemic circuit?
- Higher resistance
- Lower compliance.
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Where does the major drop in pressure occur (when going from systemic to venous), why?
- Arterioles
- Greateast resistance.
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How are (flow) velocity and cross-sectional area related?
Velocity inversely related to cross sectional area.
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What are the two largest blood reservoirs in the body?
- Systemic Veins
- Pulmonary system
- Due to: High Compliance.
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What is the Poiseuille equation?
- Q= (Pu-Pd)/R
- Q: flow
- Pu: Pressure upstream
- Pd: Pressure downstream
- R: Resistance of vessels in between.
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What are the three determinants of Resistance in a vessel?
- R (proportional to): vL/r^4
- v: Viscosity of blood
- L: Length of vessel (unchanging phsiologically)
- r: Radius of vessel -- resistance inversely proportional to the 4th power of radius -- Most important determinant of resistance.
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What are the two types of flow?
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What number helps determine laminar vs. turbulent flow?
Reynold's number: (d*vel*dens)/vis.
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Where would turbulent flow first appear in anemia, why?
Aorta: Largest diameter, Highest velocity, decreasing blood viscosity.
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What is the main factor determining capillary pressures?
- Arteriolar resistance
- Increased resistance: Decreased cap pressure
- Decreased resistance: Increased cap pressure (and flow).
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Are the bodies organs connected in series or parallel?
Parallel.
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What is the advantage of connection in parallel?
- Lower total resistance
- Individual regulation of blood flow (with changing internal resistance).
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What is the LaPlace relationship?
- T (proportional to) Pr
- T: wall tension
- P: pressure
- r: radius
- Aorta has largest wall tension because of largest radius and pressure.
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Compliance equals?
- C=dV/dP
- dV: change in volume
- dP: change in pressure.
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What is the inverse of compliance?
Elasticity: tendency to rebound.
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What is the main factor affecting systolic BP?
- Stroke volume
- Increased SV: increased systolic BP (and vice versa).
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What is the main factor affecting diastolic BP?
- Total peripheral resistance (TPR) -- arteriolar constriction/dilation
- Increased tPR: increased diastolic (and vice versa).
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Mean Pressure equals?
- MP= diastolic + 1/3 pulse pressure
- Closer to diastolic than systolic.
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What two variables determine Mean Arterial Pressure (MAP)?
- MAP= CO x TPR
- CO: Cardiac Output
- TPR: Total peripheral resistance.
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What is the function of the baroreceptor reflex?
Short term regulation of BP.
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What is the function of the RAAS?
Long term regulation of BP.
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Where are the main receptors of the baroreceptor reflex?
- Carotid sinus
- Also in the aortic arch.
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What is the Fick principle?
- Calculates blood flow through an organ
- Q= uptake/(A-V)
- Q: Flow
- uptake: O2 consumption of that organ
- A: Arterial O2 conc
- V: Venous O2 conc.
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What is the cardiac index?
- CI= CO/BSA
- CO: Cardiac output
- BSA: Body Surface Area.
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What are the two theories explaining intrinsic regulation (autoregulation) of blood flow?
- Metabolic hypothesis (more support): Tissue releases a vasodilatory substance to regulate flow
- Myogenic hypothesis: Increased pressure increases stretch, leading to contraction of arteriole.
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What is a major characteristic of an autoregulating tissue?
Blood flow is independent of blood pressure.
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What are the autoregulating tissues?
- Cerebral circulation
- Coronary circulation
- Skeletal muscle vasculature during exercise.
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Why are the kidneys not a true autoregulating tissue?
Blood flow is partially regulated through hormonal and neuronal influences.
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What is the main mechanism controlling flow in extrinsically regulated tissues?
Tonic changes in sympathetic adrenergic activity (alpha).
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What are two circulations with mainly extrinsic regulation?
- Cutaneous circulation
- Resting skeletal muscle.
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Where is the lowest venous PO2 found in the resting individual?
- Coronary circulation
- Only increase in blood flow can increase oxygen delivery to tissue (given maximal O2 extraction at rest).
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Increased cardiac pump function (work) occurs with?
- Exercise: Increased volume work
- Increased BP: Increased pressure work
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Which has a higher O2 cost, pressure work or volume work?
Pressure work.
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What is the main factor regulating cerebral blood flow (in normal conditions)?
- Arterial PCO2, directly proportional to cerebral blood flow
- Abnormal conditions: Large decrease in arterial PO2 increases cerebral blood flow (normal or elevated arterial PO2 have no effect).
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The cutaneous circulation is controlled by, varies by?
- Almost entirely by sympathetic adrenergic nerves
- Varies mainly by need for temp. exchange
- Constriction: causes elevated temp
- Dilation: causes lower temp.
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What is the pulmonary response to exercise?
- Increased CO -> increased pulm pressure
- Vessel dilation
- Apical recruitment
- --> decreased resistance --> little/no change in pulm pressure.
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What is the pulmonary response to hemorrhage?
- Decreased CO -> decreased pulm pressure
- Vessel constriction
- --> Inreased resistance --> little/no change in pulm pressure.
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What are the shunts in fetal circulation?
- Ductus Arteriosus: Pulmonary artery -> descending aorta
- Foramen Ovale: R atrium -> L atrium
- Ductus venosus: Umbilical vein -> IVC.
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What percentage of fetal CO goes to placenta?
55%.
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How does foramen ovale close?
- Increased TPR due to loss of placental circulation
- Decreased pulmonary resistance due to lung expansion
- Reversal of flow.
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What produces the S1 heart sound, when is a split heard?
- Closure of mitral and tricuspid valves
- Audible split heard: RBBB, delay in closure of tricuspid valve.
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What produces the S2 heart sound, when is a split heard?
- Closure of aortic (A2) and pulmonic (P2) valves
- Inspiration: Decreased pulmonic resistance, increased R heart output, delayed closure of P2.
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What causes a widening of S2 split?
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What causes fixed splitting of S2?
- Atrial septal defect
- L -> R shunt.
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What causes paradoxical splitting of S2?
- LBBB
- Advanced aortic stenosis.
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S3?
- Occurs righ after opening of AV valves
- children: normal, rapid expansion of compliant ventricles
- adults: volume overload, sigh of cardiac disease.
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S4?
- Atrial contraction against stiff ventricle
- examples: concentric hypertrophy, MI.
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What are the waves in the jugular venous pulse tracing?
- a wave: atrial contraction, highest deflection, PR interval
- c wave: tricuspid bulge into atrium with ventricular contraction
- x descent: atrial relaxation
- v wave: atrial filling
- y descent: ventricular filling when tricuspid valve opens.
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Draw a mental Pressure-Volume loop?
Seriously, do it.
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What are the causes of an ejection murmur?
Aortic or pulmonic stenosis.
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What are the causes of a pansystolic murmur?
- Mitral or tricuspid regurtitation/insufficiency
- Ventricular septal defect (VSD).
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What is the cause of a late systolic murmur?
Mitral valve prolapse (mid systolic click).
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What are the causes of early diastolic murmurs?
Aortic/pulmonic regurgitation/insuffiency.
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What are the causes of mid to late diastolic murmurs?
Mitral or tricuspid stenosis.
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