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51 Cards in this Set

  • Front
  • Back
3 major functions of the cardiovascular system:
*Deliver oxygen-carrying blood to the tissues

*Provide nutrients to the cells

*Remove waste products from cells
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.
*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.
Discuss 2 "other" functions of the CV system:
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
Cardiovascular anatomy:
LA is posterior!
Path of blood flow through Heart and Lungs with pressures listed at each step:
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.
Diagrams of blood/gas exchange:
*Very extensive capillary bed in the lungs, obviously.
*O2 and CO2 diffuse directly across endothelial wall.
Anatomical location of the pulmonary veins:
Coronal view of left atrial anatomy:
Coronal view of left ventricular anatomy:
Coronal view of aortic valve anatomy:
Coronal view of right ventricle and pulmonic valve anatomy:
Right heart cardiac blood flow:
Left heart cardiac blood flow:
Entire heart cardiac blood flow:
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
Describe traits of arteries:
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
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
Diagram of the microcirculation:

What adjusts the flow? 2 things.
-Flow adjusted by smooth muscle constriction and precapillary sphincters.
Generic diagram of a capillary:
Continuous vs. fenestrated capillaries:
which is most common?
where are they located?
*Continuous most common (lots of places)

*Fenestrated ones located in intestines and glomeruli.
*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.
Capillaries: what's the difference in how lipid and water soluble substances cross?
*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”
Discuss selective perfusion of capillaries:
*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).
Area vs. volume of the different types of vessels:
*Note number of the vessel types (x axis).

*10^10 capillaries accounts for huge total cross-sectional area.
Equation for velocity of blood flow:
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 = 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.
Where is the v of blood highest? Why?
Highest in the Aorta (lowest area...there's only one aorta!)
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
Blood flow through a vessel is determined by:
*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)
Resistance of the entire systemic vasculature is called:
“Total Peripheral Resistance” (TPR) or

“Systemic Vascular Resistance” (SVR)
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
What pressure drop would one measure to calculate the systemic vascular resistance (SVR)?
Mean arterial pressure minus mean right atrial pressure.

~90 minus ~5 = ~85 mm Hg
What pressure drop would one measure to calculate the pulmonary vascular resistance (PVR)?
Mean pulmonary arterial pressure minus mean left atrial pressure (PCWP).
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
What's the Poiseuille equation?
R = 8ηl / πr^4

Where η = blood viscosity
l = length of blood vessel
r = vessel radius (most important determinant of resistance)
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.
Calculating resistance in series and parallel:
Exact same as an electrical circuit.

Rseries = R1 + R2 + R3...

1/Rparallel = 1/R1 + 1/R2 + 1/R3...
Examples of series and parallel resistances in the vasculature:
Series: arrangement of blood vessels within an organ.
Series: arrangement of blood vessels within an organ.
In series, where is resistance the highest?
*As blood flows through the series, pressure decreases.
*As blood flows through the series, pressure decreases. Most dramatic drop is at the level of the arterioles.
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.
*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)
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.
*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.
Major influences on Reynold’s number:
Major influences on Reynold’s number:
*Blood viscosity (decreased viscosity increases turbulence – e.g. anemia)

*Velocity of flow (increased velocity increases turbulence)
*Blood viscosity (decreased viscosity increases turbulence – e.g. anemia)

*Velocity of flow (increased velocity increases turbulence)
How does blood vessel narrowing affect turbulence?
*Decreased radius occurs, but velocity increases by SQUARE of radius.

*Therefore, narrower vessels (or stenotic vessels) have higher turbulence.
Discuss compliance of blood vessels:
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.
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.
Describe the overall pressure drop in the CV system:
*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
*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.
Discuss the pulsatility of the cardiac cycle:
*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 drivi...
*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.
Mean pressures of the:
Aorta--
Arterioles--
Capillaries--
VC--
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).
Major histologic differences b/t arteries and veins:
-Media (smooth muscle) much thicker in artery.
-Internal elastic lamina thick in artery; almost non-existent in veins.
-Adventitia is much the same.
-Media (smooth muscle) much thicker in artery.
-Internal elastic lamina thick in artery; almost non-existent in veins.
-Adventitia is much the same.
Overall diagram of circulatory system from Costanzo--xs areas, velocity, blood volume, and pressure:
Note higher xs area of capillary bed in the lungs compared to systemic!
*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.
How do you know the severity of a bruit?
Pitch.

High pitch is bad!