Heller Ch. 6 Flashcards by Joseph Marvin

What are the units for transport rate?

Mass/time

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How is transport rate calculated?

Flow rate x concentration (Volume/time) x (mass/volume) = mass/time

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What are the four determinants to diffusion?

The concentration difference
The surface area of exchange
The diffusion distance
The permeability of the capillary wall to the diffusing substance

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What two types of pressure influence transcapillary fluid movement?

Hydrostatic pressure Osmotic pressure

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Is hydrostatic pressure higher in the interstitial or intracapillary fluid?

Intracapillary (25mmHg) P_c

Interstitial (0mmHg) P_i

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What is osmotic pressure?

Hydrostatic pressure necessary to prevent osmotic water movement

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What is Oncotic pressure?

Part of osmotic pressure

Particle concentration due to particles that cannot diffuse

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Is the oncotic pressure higher in the capillary or in the interstitial fluid?

Capillary (25mmHg) π_c

Interstital fluid (0mmHg) π_i

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What is the effect of the oncotic pressure?

Fluid goes back into the plasma

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What is the net filtration rate?

K[(Pc – Pi) – (πc – πi)]

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What is the role of the lymphatic system?

To remove large molecules from the interstitial space

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Why is it important to remove large molecules from the interstitial space?

A build up in large molecules in the interstitial space would decrease the osmotic pressure difference…fluid would build up

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What promotes lymphatic activity?

Increases in interstitial pressure (due to fluid accumulation or to movement to surrounding tissue)

Contractions of the lymphatic vessels…valves prevent back flow

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What is the resistance of vessels arranged in parallel?

(1/R_T) = (1/R₁) + (1/R₂) + … + (1/R_n)

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What is the resistance of vessels in series?

R_T = R₁ + R₂ + … + R_n

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How does blood flow velocity relate to the vessel’s total cross-sectional area?

As the total cross-sectional area increases–i.e. capillaries–the velocity goes down

What is laminar flow?

Orderly, streamlined flow

Little mixing

What causes turbulent flow?

Fluid being forced to move too fast through a narrow opening

What happens as a result of turbulent flow?

Mixing

Sounds–cardiac murmurs, bruits, checking blood pressure

What is the percentage of blood volume in the arteries? Arterioles? Capillaries? and Venules/Veins?

Arteries: 12%

Arterioles: 2%

Capillaries: 5%

Venules/Veins: 60%

Where is the peripheral venous pool?

Veins of the systemic organs

Where is the central venous pool?

Great veins of the thorax

Right atrium

What happens to the blood pressure as blood goes through the different vessels?

Blood pressure decreases to 0 by the time it gets to veins

The vessels are in a series so the resistance increases

What is the resistance across organs?

Organs are in parallel

What is Compliance in relation to volume/pressure?

Compliance is the volume change in response to a pressure change C = ΔV/ΔP

What is arterial compliance?

Arteries have very little change in volume relative to change in pressure

What is venous compliance?

Veins have a large change in volume relative to the change in pressure

Why is arterial elasticity important for conserving energy?

Expansion during systole and contraction during diastole keeps the blood moving...without relying on the heart pumping

What are Korotkoff sounds?

During auscultation for systolic/diastolic blood pressures Rely on turbulence caused by collapsed vessels

What is the relationship between arterial pressure, cardiac output, and total peripheral resistance?

P_A = CO x TPR

How is mean arterial pressure determined from systolic and diastolic pressures?

P_A = P_D + 1/3(P_S – P_D)

What is the relationship between pulse pressure, stroke volume, and arterial compliance?

P_P = P_S – P_D = SV/CA

How does arterial compliance change with age?

Older arteries have a higher pressure change for a given volume changes

What is the effect of constricting venous smooth muscles on venous volume?

There will be a lower volume for a given pressure