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51 Cards in this Set
- Front
- Back
3 major functions of the cardiovascular system:
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*Deliver oxygen-carrying blood to the tissues
*Provide nutrients to the cells *Remove waste products from cells |
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Function of:
arteries-- veins-- capillaries-- |
*Arteries carry blood from the heart to the tissues.
*Veins carry blood from tissues back to the heart. *Thin-walled capillaries, interposed between arteries & veins allow exchange of nutrients, wastes and fluid. |
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Discuss 2 "other" functions of the CV system:
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1) “Homeostatic” functions
-Regulation of blood pressure (baroreceptors) -Regulation of body temperature -Facilitates adjustments to altered physiologic states -Exercise -Change in posture -Hemorrhage 2) Delivery of endocrine hormones to sites of action in tissues |
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Cardiovascular anatomy:
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LA is posterior!
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Path of blood flow through Heart and Lungs with pressures listed at each step:
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The big picture of blood flow. What % of the blood is present in the:
brain-- coronaries-- renal-- GI-- skeletal muscle-- skin-- |
*GI varies by time of day and activity (less in running)
*Renal large % for use and filtering. |
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Diagrams of blood/gas exchange:
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*Very extensive capillary bed in the lungs, obviously.
*O2 and CO2 diffuse directly across endothelial wall. |
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Anatomical location of the pulmonary veins:
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Coronal view of left atrial anatomy:
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Coronal view of left ventricular anatomy:
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Coronal view of aortic valve anatomy:
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Coronal view of right ventricle and pulmonic valve anatomy:
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Right heart cardiac blood flow:
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Left heart cardiac blood flow:
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Entire heart cardiac blood flow:
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How is CO distributed to organs?
How is is regulated? Give approximate distributions by organ system: |
*Cardiac output distributed to organs in parallel.
*Distribution is variable, regulated by arterioles (by arteriolar constriction and by pre-capillary sphincters). *Approximate distribution: 15% brain 5% heart 25% kidneys 25% GI 25% muscle 5% skin |
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Describe traits of arteries:
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Arteries:
*Thick-walled *High-pressure system *Become progressively smaller, branching into arterioles *Site of arteriolar resistance *Alpha-1 and Beta-2 receptors Veins: *Thin-walled *Low-pressure system *Large capacitance *Small branches are called “venules” *Also innervated by sympathetic nervous system |
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Describe traits of capillaries:
what 4 things get exchanged here? |
*Lined with a single layer of endothelial cells.
*Surrounded by basal lamina. *Are the site of exchange of: -Nutrients -Gases -Water -Solutes |
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Diagram of the microcirculation:
What adjusts the flow? 2 things. |
-Flow adjusted by smooth muscle constriction and precapillary sphincters.
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Generic diagram of a capillary:
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Continuous vs. fenestrated capillaries:
which is most common? where are they located? |
*Continuous are most common (found lots of places). Pinocytotic vesicles are necessary to bring water actively into continuous capillaries. Water can also come in across junctions b/t capillaries.
*Fenestrated ones are located in intestines and glomeruli. Adapted to bring water-soluble substances in more easily. |
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Capillaries: what's the difference in how lipid and water soluble substances cross?
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*Lipid-soluble substances (e.g. oxygen and CO2) cross the endothelial cell membranes.
*Water-soluble substances (e.g. ions) cross either through: -Water-filled clefts between cells -Large pores in walls of “fenestrated” capillaries -Pinocytotic vesicles via “transcytosis” |
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Discuss selective perfusion of capillaries:
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*Not all capillaries are perfused at all times (e.g. during exercise).
*Perfusion is governed by dilation or constriction of arterioles and pre-capillary sphincters. *Regulated by sympathetic innervation of blood vessels and vasoactive metabolites which act locally (at tissue level). |
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Area vs. volume of the different types of vessels:
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*Note number of the vessel types (x axis).
*10^10 capillaries accounts for huge total cross-sectional area. |
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Equation for velocity of blood flow:
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Velocity = rate of a displacement of blood per unit time
Defined as: v = Q/A v = velocity in cm/sec Q = flow in mL/sec A = cross sectional area (cm2) *Velocity increases if area decreases. |
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Where is the v of blood highest? Why?
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Highest in the Aorta (lowest area...there's only one aorta!)
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Where is v of blood lowest? Why?
How much slower is this than flow in the aorta? |
*Capillaries (greatest area; 10^10 capillaries!)
*Allows for more time for exchange of nutrients, etc. *Velocity in aorta ~ 800 x velocity in capillaries |
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Blood flow through a vessel is determined by:
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*Pressure difference at each end of the vessel
*Resistance of the vessel to blood flow ∆V = IR or ∆P=QR Where: Q = flow (mL/min) ΔP = Pressure difference (mm Hg) R = Resistance (mm Hg/mL/min) |
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Resistance of the entire systemic vasculature is called:
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“Total Peripheral Resistance” (TPR) or
“Systemic Vascular Resistance” (SVR) |
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The blood flow to the left kidney is measured at 500 mL/min. The pressure in the renal artery is 100 mm Hg. The pressure in the renal vein is 10 mm Hg.
Question: What is the vascular resistance of the left kidney? |
R = ΔP / Q
R = (100 – 10) / 500 = 0.18 mm Hg/mL/min |
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What pressure drop would one measure to calculate the systemic vascular resistance (SVR)?
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Mean arterial pressure minus mean right atrial pressure.
~90 minus ~5 = ~85 mm Hg |
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What pressure drop would one measure to calculate the pulmonary vascular resistance (PVR)?
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Mean pulmonary arterial pressure minus mean left atrial pressure (PCWP).
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Determinants of vascular resistance include what 3 things?
What equation describes this? |
Blood vessel diameter, blood vessel length, and viscosity of the blood.
*Poiseuille equation |
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What's the Poiseuille equation?
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R = 8ηl / πr^4
Where η = blood viscosity l = length of blood vessel r = vessel radius (most important determinant of resistance) |
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Relationship of resistance to:
viscosity-- length-- radius-- |
*Resistance increases as viscosity increases.
*Resistance increases as length increases. *Resistance increases as radius decreases to the fourth power. |
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Calculating resistance in series and parallel:
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Exact same as an electrical circuit.
Rseries = R1 + R2 + R3... 1/Rparallel = 1/R1 + 1/R2 + 1/R3... |
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Examples of series and parallel resistances in the vasculature:
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Series: arrangement of blood vessels within an organ.
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In series, where is resistance the highest?
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*As blood flows through the series, pressure decreases. Most dramatic drop is at the level of the arterioles.
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Laminar vs. turbulent flow:
What's the word for turbulent flow in the heart? What's the word for turbulent flow in the vessels? |
*Ideally, blood flow in the cardiovascular system is laminar.
*Laminar flow implies a parabolic profile of velocity. *Irregularities in the vessel cause turbulent flow. *In turbulent flow, streams are propelled radially and axially *More energy is required *Turbulent flow in the heart can cause a “murmur” *Turbulent flow in blood vessels can cause a “bruit” (blocked carotid bruit is easy to hear) |
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What is Reynold's number?
What does it predict? |
*Reynold’s number is a dimensionless number used to predict whether blood flow is laminar or turbulent.
*NR < 2000 predicts laminar flow. *NR > 2000 predicts turbulent flow. |
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Major influences on Reynold’s number:
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*Blood viscosity (decreased viscosity increases turbulence – e.g. anemia)
*Velocity of flow (increased velocity increases turbulence) |
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How does blood vessel narrowing affect turbulence?
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*Decreased radius occurs, but velocity increases by SQUARE of radius.
*Therefore, narrower vessels (or stenotic vessels) have higher turbulence. |
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Discuss compliance of blood vessels:
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Compliance in a blood vessel is similar to compliance of the heart:
*Compliance is proportional to ΔV / ΔP. *Compliance of veins is high – (veins can hold large volume of blood at low pressure). *Compliance of arteries is lower – (they hold a lower volume at a higher pressure). *Older arteries are least compliant. |
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Compare compliance of veins, arteries, and aging arteries:
What was an early treatment for HTN and why is it related to compliance? |
Plot on the left shows compliance (∆V/∆P).
Early treatment for HTN was a diuretic--decreasing volume decreases BP. |
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Describe the overall pressure drop in the CV system:
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*There is a progressive drop in mean pressure as blood flows from:
-The aorta: to the arteries, to the arterioles, to the capillaries, to the venules and to the great veins. -The largest pressure drop occurs at the arteriolar level. |
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Discuss the pulsatility of the cardiac cycle:
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*Arterial pressure is pulsatile, due to the cardiac cycle:
-Systolic pressure represents the highest pressure in the pressure tracing. -Diastolic pressure represents the lowest pressure in the pressure tracing. -MEAN pressure is the driving pressure, and is calculated as: Diastolic pressure + 1/3 of the pulse pressure. |
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Mean pressures of the:
Aorta-- Arterioles-- Capillaries-- VC-- |
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What happens to blood pressure with:
The aging process? Stenosis of the subclavian artery? |
Aging: BP increases (decreased compliance, narrower vessels?).
Stenosis of subclavian: BP in unblocked arm would be normal. BP in blocked arm would be lower (increased resistance causes pressure drop). |
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Major histologic differences b/t arteries and veins:
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-Media (smooth muscle) much thicker in artery.
-Internal elastic lamina thick in artery; almost non-existent in veins. -Adventitia is much the same. |
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Overall diagram of circulatory system from Costanzo--xs areas, velocity, blood volume, and pressure:
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*Note higher xs area of capillary bed in the lungs compared to systemic!
*Note velocity of capillary flow. *Note capacitance of veins compared to arteries. *Note loss of "Phases" at the level of the arterioles. Pressure drops b/c of resistance--it's just a blunted pressure at that point. |
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How do you know the severity of a bruit?
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Pitch.
High pitch is bad! |