Transcript Circulation2

Last Day: Blood Vessels
C5-a: Identify & give functions for main arteries
& veins
C5-b: Describe & differentiate between the 5
vessel types (size, structure, direction of blood)
C5-c: Differentiate between systemic &
pulmonary circulatory systems
Today: Blood Vessels
C5-d: Demonstrate knowledge of path of blood cell
throughout body
C5-e: Relate blood pressure & velocity to crosssectional areas of vessels
C5-f: Describe capillary-tissue fluid exchange
Think About It
What materials are being exchanged at the
capillary interface?
What materials leave the capillary into the
body tissues?
What materials enter the capillary at the body
tissues?
Recall that...
• Solutes in solution go from areas of high
CONCENTRATION to low
• Water moves from areas of low SOLUTE
CONCENTRATION to high (osmotic pressure)
• Fluids & solutes will go from areas of high
PRESSURE to areas of low (blood pressure)
 Blood ENTERS capillary under pressure
 Pressure forces some fluid & solutes out of the
blood (not red blood cells or large proteins)
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 Most of the fluid is then recaptured by the venule
end of the capillary
 Pressure decreases along the capillary bed
 Proteins in the blood (ex. albumen) create an osmotic
force that draws fluid back into blood
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 Lymphatic system will collect fluid that is not
captured and return it to the blood
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Think About It
What materials will
leave the blood after
point X?
Online quizzes + Animations
• http://www.phschool.com/science/biology_pl
ace/biocoach/cardio2/endothelium.html
• http://highered.mcgrawhill.com/classware/ala.do?isbn=0072956208&
alaid=ala_996537&showSelfStudyTree=true
• http://www.mhhe.com/biosci/genbio/espv2/d
ata/animals/006/index.html
Think About It
In which vessels is the speed of blood flow the
fastest? Why?
 In which vessels is the speed of blood flow
the slowest? Why?
Think About It
Identify W, X, and Y
from the following
choices:
 Cross sectional area
 Blood velocity
 Blood pressure
• As blood travels further from heart, blood
pressure DECREASES
Blood Pressure
• Although capillaries are very tiny in diameter,
they are numerous. Therefore, all capillaries
together have a far greater cross-sectional
area than arteries or veins
Cross-Sectional Area
• Velocity of blood DECREASES with an
INCREASE in total cross-sectional area
Blood Velocity
• The velocity of blood flow varies in the vessels
Systolic
pressure
Venae cavae
Veins
Venules
Capillaries
Diastolic
pressure
Arterioles
120
100
80
60
40
20
0
Arteries
Velocity (cm/sec)
50
40
30
20
10
0
Aorta
Figure 42.11
5,000
4,000
3,000
2,000
1,000
0
Pressure (mm Hg)
Area (cm2)
– is slowest in the capillary beds as a result of the high
resistance & large total cross-sectional area
PLO Journal
C5-e:
1) Account for the changes in pressure, velocity, and cross-sectional
area in blood vessels.
- pressure in vessels decreases as get further from heart
- cross-sectional area is highest in capillaries due to greater number
- velocity decreases in arteries as get further away from heart, and
is lowest in capillaries (due to a high cross-sectional area) – velocity
starts to increase as blood rejoins into veins
2) Explain how pressure and velocity help with tissue fluid exchange
at the capillaries.
- blood entering capillaries is under high pressure, causing
fluids/solutes to diffuse into tissues – as blood continues through
capillaries, pressure drops and fluids/solutes diffuse back into blood
- velocity slows down in capillaries, allowing more time for exchange
PLO Journal
C5-f:
1) Describe how the capillary is well suited for tissue fluid exchange.
-
Capillary walls are only one cell thick
Capillaries are narrow in diameter, keeping RBC’s in close proximity to tissues,
and resistance slows down blood
Capillaries receive blood high in pressure
2) Sketch a diagram at the capillary level to help show how eating salty
foods can contribute to high blood pressure.
-
Diagram should show high concentration of salt in blood (capillaries), which
creates a greater osmotic force to draw water into capillaries, thus increasing
blood pressure
3) Describe tissue fluid exchange at the capillary .
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Fluids/solutes diffuse out of capillaries due to high blood pressure (which is
greater than the osmotic force to draw fluid into the blood)
As blood pressure decreases, osmotic force is then greater and fluids move into
the capillaries to dilute the high concentration of protein in the blood