Vascular Phys Flashcards by Daddy'sLittlePickle .

Layers of the blood vessel wall:

Tunica Intima
Tunica Media
Tunica Adventitia

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Tunica Intima contains:

endothelial cells

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Tunica Media contains:

smooth muscles cells (for contraction)

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Tunica Adventitia:

connective tissue and vasa vasorum (blood vessels)

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Arteries have ________ vessel walls

thick

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Arteries have walls that are _______ & _________

elastic
compliant/distensible

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What is compliance?

how much volume changes in response to distending pressure

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In high pressure vessels like arteries, blood volume is often referred to as ________ ________

stressed volume

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Arteries have high velocity blood flow because __________

they have the smallest cross-sectional area

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Arterioles branch off _______ & go into _________

arteries
capillaries

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Vessels with the greatest resistance in the circulation are called _______

arterioles

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Arterioles are control vessels - lots of _________ nerves

autonomic

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What are precapillary sphincters and where are they found?

bands of circular smooth muscle between arterioles and capillaries; can contract and close off different capillary beds

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What are metarterioles and where are they found?

anastomoses between arterioles and venules; blood bypasses capillary

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Capillaries are sites of ________ with interstitial fluid

exchange

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Capillaries are the _________ sized blood vessels and have the ________ velocity of blood flow

smallest; slowest (bc they have the largest cross-sectional area)

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There is a _______ level of blood flow in the capillaries

low

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3 types of capillaries

Continuous
Fenestrated
Sinsuoidal

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________ capillaries are the smallest; tight junctions reinforce (ex: blood brain barrier, bladder)

Continuous

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________ capillaries are medium-sized; leaky with openings (ex: small intestines, kidneys, exocrine glands)

Fenestrated

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________ capillaries are largest; least specific with huge openings (ex: bone marrow, spleen, liver)

Sinusoidal

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_______ ________ venules allow for exchange across vessel walls

post-capillary

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__________ begins at post-capillary venules

angiogenesis

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venules involve _________ innervation

sympathetic

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veins are ______ vessels: largest blood volume of all vessels - unstressed volume

capacitance

Highest compliance vessels are _______

veins

Vascular smooth muscle can ________ & ________ to alter venous return to the heart based on __________ innervation

constrict; dilate; autonomic

Which has the lowest pressure of all vessels?

veins

One way flow in veins depends on ________

valves

________ muscle pumps necessary for flow, particularly against gravitational pressure

skeletal

________ pressure on veins in feet is significant

gravitational

Anytime there is a lot of pressure within a particular vessel, it stretches the _______ and ALSO the ________

vein; valves

What are varicose veins?

valves can become so stretched that they can no longer close completely - no longer prevent backflow

Lumens are larger in all _______ than _________

veins; arteries

Where is the largest lumen located?

vena cava

Distribution of blood volume (%) in different parts of the body: 1. systemic circulation 2. pulmonary circulation 3. heart

1. 84% 2. 9% 3. 7%

At any given time, what % of blood is stored in veins

64%

What are the large blood reservoirs?

Large abdominal veins, liver, cutaneous venous plexus (skin) and spleen (largest)

Order cross-sectional area of vessels from largest to smallest:

(largest) capillaries venules arterioles vena cava aorta (smallest)

Even though individual capillaries are smaller, why is their TOTAL cross-sectional area much larger?

They are so numerous

Velocity of blood flow is ________ proportional to cross-sectional area

inversely

Flow is _______ (speed) through capillaries and ________ (speed) in the arteries

slowest; fastest

Why can slow flow be an advantage at exchange sites?

maximizes time available for exchange between blood & interstitial fluid

Velocity = __________ / ___________

flow / cross-sectional area (π r^2)

Throughout the vascular circuit, blood flows down a pressure gradient. This means pressure differences must ________

decrease

The volume of blood passing a given point in a period of time is blood flow. What are the units?

ml/min

In Ohm's Law, Flow = ?

∆P/R = ∆P (πr^4) / 8nl

Flow is driven by the _______ gradient & impeded by _______ _________

pressure gradient; vascular resistance

Two types of flow in vessels:

1. Laminar flow 2. Turbulent flow

What type of flow: - ideal - vessels are straight - endothelium is healthy - velocity of flow is always greater in center of vessel compared to outside

Laminar flow

What type of flow: - you can hear this one - disorderly flow - MORE than 1 direction (bruits & murmurs) - Creates eddy currents that increase resistance and friction in the vessel

Turbulent flow

Turbulent flow is more likely if:

- high velocity of blood flow - obstructed vessels - sharp turns in vessels - endothelium is rough

To maintain constant blood flow, pressure must __________

increase

__________ __________ is the calculation of flow turbulence

Reynold's Number (Re)

What is the Renyold's Number (Re) equation?

Re = (Vdp)/n

> ________ = most likely turbulent

> 2000

> _________ = always turbulent

> 3000

Turbulence is directly proportional to:

- Velocity of blood flow (V) - most important determinant - Diameter of vessel (d) - inverse to velocity - Density of blood (p) - amount of mass occupying space

Turbulence is inversely proportional to:

Viscosity of blood (n)

Turbulent flow increases:

- energy required for drive flow - Increases the risk of endothelial injury & plaque development - increases possibility of thrombotic events

Turbulent flow more common in _________ vessels & _________

atherosclerotic; anemia

In _________, a decrease in hematocrit causes a decrease in viscosity

anemia

Anemia would be expected to _________ resistance and _________ flow

decrease; increase

Atherosclerosis definition =

narrowing of arteries decreases the radius

Atherosclerotic vessels would _______ resistance and _________ flow

increase; decrease

Small changes in vessel diameter induce ________ changes in blood flow (r is to the power of 4)

large

Ejected blood distribution at rest: Right heart = Left heart =

Right heart = lungs Left heart = all other vessels

In the left heart, largest amount of blood goes to _______, ________, and _______

kidneys; gut; skeletal m.

Smaller amount of left heart blood goes to _________

brain

Smallest amount of left heart blood goes to _______ and _______

heart; skin