PSIO 241 CH 10

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48 Terms

1

blood

_ flows in a closed loop between the heart and the organs

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2

arteries

transport blood from the heart throughout the body

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3

arterioles

control the amount of blood that flows through each organ

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4

capillaries

the vessels where materials are exchanged between blood and surrounding tissue cells

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5

veins

return blood from the tissue back to the heart

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6

blood pressure

Force exerted by blood against a vessel wall

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7

systolic pressure

– Peak pressure exerted by ejected blood against vessel walls during cardiac systole

– Averages 120 mm Hg

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8

diastolic pressure

– Minimum pressure in arteries when blood is draining off into vessels downstream

– Averages 80 mm Hg

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9

pulse pressure

the difference between systolic and diastolic pressures

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10

Mean Arterial Pressure (MAP)

• the average driving pressure throughout the cardiac cycle=

2/3 (diastolic) + 1/3 (systolic)

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11

arteries

• have low resistance so are rapid-transit passageways; large radius

• act as pressure reservoir due to elastic properties to provide driving force for blood when ventricle is in diastole

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12

arterioles

• Major resistance vessels

• Have a thick layer of circular smooth muscle.

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13

high

_ resistance produces a large drop in mean pressure between the arteries and capillaries

  • This decline enhances blood flow by contributing to the pressure gradient between the heart and organs

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14

functions of arterioles when adjusted

– to variably distribute cardiac output among the organs depending on body needs'

– to help regulate arterial blood pressure

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15

parallel flow

blood across the entire system

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16

series flow

blood through individual organs

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17

priority of the circulatory system

Maintaining adequate flow to the brain

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18

hemodynamics

represents the relationship of flow, pressure and resistance

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19

increases; decreases

- Flow is inversely related to resistance.

Resistance _ so flow _

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20

pressure gradient

the difference in pressure between the beginning and the end of a vessel

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21

higher; lower

blood flows from an area of _ pressure to an area of _ pressure down a pressure gradient

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22

greater

The _ the pressure gradient the greater the flow rate through that vessel

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23

resistance

the hindrance to blood flow through a vessel

• Based on frictional forces during blood flow.

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24

resistance and r4

Doubling the radius reduces the resistance to 1/16th its original value and increases flow 16-fold.

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25

intrinsic control

Tissues have mechanisms to regulate arteriole tone; affect nutrient delivery and waste removal (metabolism)

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26

extrinsic mechanisms

exist to regulate arterioles and maintain adequate MAP; controlled by sympathetic NS.

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27

vasoconstrictor

increased sympathetic activity

Decreased metabolism

(high oxygen, low CO2, low temperature)

(extrinsic)

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28

vasodilation

decreased sympathetic activity

Increased metabolism (low oxygen, high CO2, high temperature)

(intrinsic)

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29

extrinsic control

• The cardiovascular control center in the medulla adjusts sympathetic output to the arterioles.

• NE released from sympathetic nerve bring about vasoconstriction

• This change in arteriolar resistance bring about increased mean arterial pressure.

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30

extrinsic sympathetic

control of arteriolar radius is important in regulating blood pressure

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31

intrinsic control

• Local chemical changes associated with changes in the level of metabolic activity affect arteriole resistance

• Increased blood flow in response to enhanced tissue activity is called active hyperemia (exercising muscle)

• Can be pathological like that of inflammation

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32

septic shock

• mediated by massive vasodilation

– Cause by dilators released from bacteria (basically)

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33

neurogenic shock

loss of sympathetic innervation

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34

cardiogenic shock

• hypoperfusion due to the heart itself

• Could either be low SV and/or low HR

• Resistance isn’t the problem, it’s cardiac output

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35

capillaries

• thin-walled, small-radius, extensively branched vessels.

• Surface area for exchange is maximized

• Diffusion distance is minimized

•Large cross-sectional area results in slow blood velocity to maximize time for exchange

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36

passive diffusion

down concentration gradients is  the primary mechanism for exchanging solutes

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37

bulk flow

determines the distribution of the ECF volume between the vascular and the interstitial fluid compartments

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38

Individual solutes

_ are exchanged primarily by diffusion down concentration gradient

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39

lipid

_ soluble substances pass directly through endothelial cells lining a capillary.

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40

water

_ soluble substances pass through water-filled pores between the endothelial cells.

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41

capillary exchange

Plasma proteins generally do not escape

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42

bulk flow

• occurs when protein-free plasma filters out of the capillary, mixes with the interstitial fluid and then is reabsorbed.

• important in regulating the distribution of ECF between the plasma and the interstitial fluid to help maintain arterial blood pressure.

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43

filtration

occurs when pressure inside the capillary exceeds pressure outside and fluid is pushed out through the pores

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44

reabsorption

occurs when inward-driving pressures exceed outward pressures and net movement of fluid back into the capillaries occurs.

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45

Capillary hydrostatic

pressure pushes fluid out of the capillary bed

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46

Plasma colloid osmotic

pressure draws fluid back into the capillary bed

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47

filtered; reabsorbed

Slightly more fluid is _ out of the capillaries into the interstitial fluid than is _ from the interstitial fluid back into the plasma.

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48

lymphatic

Excess fluid left in the interstitial fluid is picked up by the _ system and returned to general circulation.

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