1. Cardiovascular System: Circulation Pathways and BP Regulation
Anatomy & Physiology II
Tony Serino, Ph.D.
Biology Department
Misericordia University

2. Blood Vessels Arteries –conduct blood away from heart
Elastic arteries, Muscular arteries, arterioles
Veins –conduct blood toward heart
Venules, small and large veins
Capillaries –thinnest blood vessel; used in exchange, is the functional unit of circulatory system (Microcirculation)
AV shunts, metarterioles, pre-capillary sphincters, and capillary bed

3. Blood Vessels Types

4. Capillary Anatomy
Three types: tight, fenestrated and sinusoids

5. Capillary Types Tight Capillary Fenestrated Capillary
Sinusoidal Capillary

6. Capillary Bed (blood flowing)

7. Capillary Bed (blood shunted)

8. Capillary Transport Pathways

9. Forces Affecting Bulk Flow across the Capillary Wall

10. Arteries and Veins
Arteries are known as resistance vessels, especially the arterioles
Arteries withstand the greatest BP
Veins are capacitance vessels, they are able to change the diameter to hold more or less blood

11. Artery vs. Vein

12. Artery Anatomy (CT) (Smooth Muscle)
(Controlled by sympathetic system = vasomotor nerves)

13. BP through Vascular Tree
Small changes in arteriolar diameter produce big changes in resistance; termed total peripheral resistance (TPR)

14. TPR (total peripheral resistance)
TPR is the opposition to blood flow through the vessel (caused by friction)
Arteries with their smaller lumen resist blood flow
Arteriolar diameter contribute the most to TPR
Arteriolar compliance (the ability of the vessel to distend) controls the TPR
Sympathetic innervation controls arteriolar radius
The viscosity of the blood also affects resistance

15. Blood Flow Velocity in Vascular Tree

16. Blood Flow Changes During Exercise

17. Arterial Side

18. Blood flow in a healthy system is Laminar (smooth –no sound)
Blood flow in a unhealthy system is Turbulent (rough –noisy)

20. Atherosclerotic plaques

21. Pressure Points

22. Venous Side

23. Skeletal Muscle Pump

25. Factors Affecting CO (Review)
Starling Forces

26. Blood Pressure BP = SP/DP
Systolic Pressure (SP) –the pressure in the artery during systole
Diastolic Pressure (DP) –the pressure in the artery during diastole
Mean Arterial Pressure (MAP) (weighted average) MAP = DP + 1/3 (PP)
Pulse Pressure (PP) = SP - DP
MAP = CO x TPR

28. SP DP

31. Renal Hormonal Control of BP

32. Summary of MAP Factors