Practice Questions WITH ANSWERS |\ |\ |\
How does blood flow through the heart chambers/valves?
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Superior vena cava to inferior vena cave. Blood then enters the
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right atrium and passes through the tricuspid valve to the right
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ventricle. The right ventricle pumps the blood to the lungs
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through the pulmonary valve to the pulmonary arteries where it
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becomes oxygenated. The oxygenated blood is brought back to
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the heart by the pulmonary veins which enter the left atrium.
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From the left atrium blood flows through the bicuspid (mitral)
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valve into the left ventricle.
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Which coronary arteries provide blood to which part of the heart?
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a. ) Left coronary artery
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i.) Left anterior descending artery:widow maker
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LV and RV, intraventricular septum
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ii. ) Circumflex: LA and left lateral wall of LV.
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,b. ) Right coronary artery
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RV, intraventricular sulcus and small vessels of the RV and LV
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What factors contribute to blood flow in a vessel?
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Pressure difference between two ends of a vessel
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Resistance: r/t diameter of a vessel |\ |\ |\ |\ |\
Viscosity (n) of the blood |\ |\ |\ |\
Length (l) of the vessel |\ |\ |\ |\
What does QP: QS mean and what factors alter a normal ratio?
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Q=blood flow |\
QP= blood flow to the lungs (pulmonary) : QS= blood flow to the
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body (systemic) |\
i ) Vascular resistance =measures in woods units
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ii) Pulmonary vascular resistance (PVR)
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1. ) <8 weeks of age: 8-10 woods units/m2
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2. ) >8 weeks of age: 1-3 woods units/m2
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iii) Systemic vascular resistance
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1. ) Infant 10-15 woods units/m2
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2.) 1-2 years old: 15-20 woods units/m2
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,3.) Child to adult: 15-30 woods units/m2
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a) Factors affecting resistance
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i.) Compliance-ease that blood travels through the arteries
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1. Constriction and relaxation of smooth muscle of arteries and
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arterioles
a. ) Sympathetic nervous system
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b.) Local tissue metabolism
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c.) Hormone responses
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d.) Changes in chemical environment
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Explain the process of cardiac contraction and relaxation.
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What are the roles of actin, myosin, and troponin in this process?
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At rest, active sites on actin are blocked by troponin and
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tropomyosin complexes. During action potential, troponin C binds |\ |\ |\ |\ |\ |\ |\
with calcium and moves the complexes off the actin active site.
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Actin and myosin interact (contract).
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"Walk-along" theory: |\
Head of myosin cross-bridge attached to the actin filament at the
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active site.
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Intra molecular forces cause the myosin head to tilt forward on a
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flexible hinge and drag the actin filament with it (power stroke)
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Myosin head breaks away and interacts with the next actin active
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site.
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, Z disc pulls filaments together at the sarcomeres= muscle
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contraction.
What is the effect of Epinephrine on the cardiovascular system?
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Stronger Alpha 1 than Alpha 2. Works on both, equally strong on
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Beta 1 (renin release), and Beta 2. Positive inotrope. Increases
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heart rate, smooth muscle contraction, myocardial contractility,
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coronary flow, increase systolic blood pressure, mild increase in
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diastolic blood pressure. |\ |\
What is the effect of Norepinephrine on the cardiovascular
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system?
Slightly stronger Alpha 2 than Alpha 1. Some effect on Beta 1,
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none on Beta 2. Strong vasoconstriction (smooth muscle
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contraction). Increase coronary flow, increase systolic and some
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diastolic BP. |\
What is the effect of Dopamine on the cardiovascular system?
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Positive inotrope. Increases HR, increases BP (vasoconstriction)
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Alpha 1, 2, beta 1 and dopamine receptors)
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What is the process of generating a cardiac action potential?
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What electrolytes are involved?
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