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

2. Blood Vessels Types 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. Capillary
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4. Capillary Types Tight Capillary Fenestrated Capillary
Sinusoidal Capillary

5. Capillary Bed
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6. Forces Affecting Bulk Flow across the Capillary Wall

7. Artery vs. Vein
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

8. Pressure Changes down CV tree
Small changes in arteriolar diameter produce big changes in resistance; termed total peripheral resistance (TPR)
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9. Elastic Recoil and Artery Contraction
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10. Arterial Pressure Curve
(Dicrotic Notch)
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11. 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

12. Small changes in Arteriole Diameter create large changes in BP
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13. Blood Flow Velocity in Vascular Tree

14. Blood Flow Regulation is mainly a Local Response
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Understand Reactive Hyperemia and Inflammation; ANS control modifies BF based on “whole body needs”

15. ANS Control of Arterioles
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(Alpha receptors outnumber Beta in most vascular beds; except in skeletal muscles. Here epinephrine causes vasodilation)

16. Modifiers of Arteriolar Radius
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17. Adjustment of Perfusion to Exercise
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18. CV Adjustment to Exercise
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19. Some Exercise Physiology Mechanisms
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20. Atherosclerotic plaques are a primary cause of hypertension due to Increase in TPR

21. Capacitance Vessels (Veins)
Skeletal Muscle Pump
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22. Fig
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23. 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

25. SP DP

26. Baroreceptor Locations

27. 3. Increased parasympathetic
Carotid sinus
baroreceptors
1. Baroreceptors in the carotid sinus and aortic arch monitor blood pressure.
2. Action potentials are conducted by the glossopharyngeal and vagus nerves to the cardioregulatory and vasomotor centers in the medulla oblongata.
3. Increased parasympathetic
stimulation of the heart decreases the heart
rate.
4. Increased sympathetic stimulation of the heart increases the heart rate and stroke volume.
5. Increased sympathetic stimulation of blood vessels increases vasoconstriction. 1
Aortic arch
baroreceptors
Glossopharyngeal nerve 3
Vagus nerve 2
Vagus nerve (parasympathetic)
Cardioregulatory
and vasomotor
centers in the
medulla oblongata 4
Sympathetic
nerves
Sympathetic
chain 5
Blood vessels

28. Better at controlling BP drops than rise
Better at controlling BP drops than rise. High BP causes shift in set point of receptors similar to exercise.

29. Baroreceptor Reflex (Note: if decrease BP: arrows reverse)
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30. Renal Hormonal Control of BP
(ACE)
↑ BP
↑ blood volume

31. Other Renal Mechanisms affecting BP
(ADH)
↑ blood volume
↑ BP
↓ blood volume
↓ BP

32. Mechanism of BV changes on BP
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33. Overview of BP Regulation
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34. 12.08.jpg

35. Hemorrhage
Compensation Response
Primary Effects
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36. Fig
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37. Fig
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38. Fig
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39. Elephantiasis
Vector : mosquito Pathogen: filaria worms blocking lymph vessels
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