Pages 382-390

Alternating expansion and recoil of a blood vessel wall (the pressure wave) that occurs as the heart beats

Locate arterial pulse at “pressure points” in superficial arteries These same points are used to stop blood flow

due to hemorrhage from injury Avg is 70-76 bpm at rest for a healthy

person

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Superficial temporal artery

Facial artery

Common carotid artery

Brachial artery

Radial artery

Femoral artery

Popliteal artery

Posterior tibialartery

Dorsalis pedis artery

Blood pressure is: the pressure the blood exerts against the inner walls of the blood vessels

Blood is forced along a descending pressure gradient

◦ Pressure is highest in the large systemic arteries, lower in the capillaries, and lowest in the veins

Elasticity of vessels is pertinent to healthy, elastic arteries

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Figure 11.20 Blood pressure in various areas of the cardiovascular system.

Systolic pressure

Diastolicpressure

120

100

80

60

40

20

0

–10

Pre

ssu

re (

mm

Hg

)

Ao

rta

Art

erie

s

Art

erio

les

Cap

illa

rie

s

Ve

nu

les

Ve

ins

Ve

nae

ca

vae

Systolic—pressure at the peak of ventricular contraction

Diastolic—pressure when ventricles relax

Expressed as systolic over diastolic◦ 120/80 mm Hg is average◦ The brachial artery is used for measurement

Hypotension- low blood pressure (<100 sys.) Hypertension- high blood pressure

(>140/90)

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1. Resistance within blood vessels (increases)2. Kidneys regulate blood volume via

enzymes3. Temperature-

1. cold causes vasoconstriction2. Heat causes vasodilation

4. Chemicals 1. Hormones like epinephrine2. Drugs/nicotine3. Diet

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Gas and nutrient exchange occurs through capillary walls◦ Driven by concentration gradients

Oxygen and nutrients go from blood to tissues Carbon dioxide and other wastes go from tissue to blood

Substances diffuse through the interstitial fluid (tissue fluid) found between cells

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1. Direct diffusion through membranes2. Diffusion through intercellular

clefts/gaps3. Diffusion through pores4. Transport via vesicles (bulk transport)

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Directdiffusionthroughmembrane

1 Diffusion throughintercellular cleft/gap2

Diffusionthrough pore3

Transportvia vesicles4

Interstitial fluid

Lumen ofcapillary Vesicles

Intercellularcleft

pore

Blood pressure forces fluid and solutes out of capillaries at the arterial end

Osmotic pressure draws fluid into capillaries at the venous end

At the arterial end, BP > OP At the venous end, BP < OP

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Tissue cell Interstitial fluid

Net fluidmovementout

Net fluidmovementin

Arterialend ofcapillary

Venuleend ofcapillary

Blood pressure ishigher than osmoticpressure

At the venule end ofthe capillary, bloodpressure is less thanosmotic pressure,and fluid flows fromthe interstitial fluidinto the capillary.

Blood pressure islower than osmoticpressure

Osmotic pressureremains steadyin capillary bed

At the arterial end ofa capillary, bloodpressure is more thanosmotic pressure,and fluid flows out ofthe capillary and intothe interstitial fluid.