1. Components of the Circulation.
Components of the Circulation
Figure 14-1; Guyton and Hall

2. The Capillaries Have the Largest Total Cross-sectional Area of the Circulation
cm2
Aorta
Small Arteries
Arterioles
Capillaries
Venules
Small Veins
Venae Cavae

3. Velocity of Blood Flow is Greatest in the Aorta
Velocity of Blood Flow = Blood Flow
Cross sectional area
Aorta >Arterioles > Small veins >Capillaries

4. The Majority of Blood Volume is in the Veins.
Figure 14-1; Guyton and Hall

5. Blood Pressure Profile in the Circulatory System1 2 1
Arterioles
Capillaries
Venules
Pulmonary viens 8
Pressure
(mmHg)
Pulmonary arteries 6
Capillaries
Small viens
Large viens
Venae cavae
Venules 4
Large arteries
Small arteries
Arterioles 2
Aorta
Systemic Pulmonary
High pressures in the arterial tree
Low pressures in the venous side of the circulation
Large pressure drop across the arteriolar-capillary junction

6. Variations in Tissue Blood Flow
Percent ml/min
Brain
Heart
Bronchi
Kidneys
Liver
Portal (21) (1050)
Arterial (6) (300)
Muscle (inactive state)
Bone
Skin (cool weather)
Thyroid gland
Adrenal glands
Other tissues
Total

7. Characteristics of Blood Flow
When laminar flow occurs, the velocity of blood in the center of the vessel is greater than that toward the outer edge creating a parabolic profile.
Laminar flow
Blood Vessel

8. Laminar Vs. Turbulent Blood Flow
Turbulent flow
Laminar flow is silent, whereas turbulent flow tend to cause murmurs.
Murmurs or bruits are important in diagnosing vessels stenosis, vessel shunts, and cardiac valvular lesions.

9. Effect of Wall Stress on Blood Vessels
Turbulent flow increases wall stress

10. Parallel and Serial Resistance Sites in the Circulation

11. Effect of Vessel Diameter on Blood Flow
Conductance is very sensitive to change in diameter of vessel.
The conductance of a vessel increases in proportion to
the fourth power of the radius.
Figure 14-9; Guyton and Hall

12. Determinants of Blood Flow
FLOW = arterial - venous pressure (P)
resistance (R)
100 mmHg
100 mmHg A B
0 mmHg
20 mmHg
R = .1mmHg/ml/min
R = .1mmHg/ml/min
FLOW = mmHg
.1 mmHg/ml/min
FLOW = mmHg
FLOW = 1000 ml/min
FLOW = 800 ml/min

13. How Would a Decrease in Vascular Resistance Affect Blood Flow?
FLOW = P
RESISTANCE
Conversely,
FLOW = P
RESISTANCE

14. Hematocrit and Viscosity Effects on Blood Flow
Figure 14-11; Guyton and Hall
Figure 14-12; Guyton and Hall

15. Arterial Pulsations
The height of the pressure pulse is the systolic pressure (120mmHg), while the lowest point is the diastolic pressure (80mmHg).
The difference between systolic and diastolic pressure is called the pulse pressure (40mmHg).
Systolic Pressure }
Pulse Pressure
Diastolic Pressure

16. Damping of Pulse Pressures in the Peripheral Arteries
Figure 15-6; Guyton and Hall

17. } Arterial Pulse Systolic Pressure Diastolic Pressure Pressure Time
Stroke
volume
Cardiac
output
Systolic Pressure }
Mean
Pressure
Pulse Pressure
Diastolic
Pressure
Arterial
compliance
Peripheral
resistance
Pressure
Time

18. Abnormal Pressure Pulse Contours
Figure 15-4; Guyton and Hall

19. Pulse Pressure and Age
Figure 15-8; Guyton and Hall

20. Effect of Cuff Pressure on Brachial Blood Flow
NO FLOW
FREE FLOW
Cuff Pressure < 80

21. Measurement of Blood Pressure
Use of Korotkoff Sounds
150
100 50