1. Compliments of Gary Larson Pre-Lab Lecture

2. Blood Vessels and Circulation Chapter 13

3. Peripheral Circulation: Systemic Circulation: Blood vessels directing blood to the body tissues Left Heart to Right Heart Pulmonary Circulation: Blood vessels directing blood to the lungs for gas exchange Right Heart to Left Heart

4. Functions: Carry Blood: “Duh!” Gas and Nutrient Exchange: O 2 /CO 2, Energy substrates, Minerals, H 2 O and wastes Transport: “Special delivery”: Supply/Demand Regulate Blood Pressure: Perfusion Homeostasis (More…)

5. Perfusion Homeostasis: Internal Environment: Depends on appropriate perfusion (Blood flow) Homeostasis: A constant balance of choices in maintaining blood pressure and distribution to demanding tissues

6. Important Homeostasis Key! Since Blood transports life sustaining substances… Appropriate Perfusion (Circulation) is the Key to Homeostasis!

7. Arteries: Vessels taking blood Away From The Heart Usually O 2 and nutrient rich…”Supply” to tissues

8. Arteries: Structure/Function High Pressure Conduits: Elastic Connective Tissue: Expands with systole, and recoils with diastole Smooth Muscle: Assist in “pumping” and “directing” blood flow Endothelium: Smooth inner surface

9. Veins: Vessels returning blood Back To The Heart Usually low in O 2 – carrying wastes for removal

10. Veins: Structure/Function Low Pressure “Pools”: Sometimes called “capacitance vessels” because they have a large resevoir (capacity) for blood Less connective tissue and smooth muscle than arteries Endothelium: Specialized valves assist blood flow toward heart

11. Check Out Those Valves! Locate the veins in your forearm or hand Place your index finger on a vein, then “milk” the vein toward your shoulder with your thumb…

12. NEXT… Leave the finger in place and observe if the blood flows back when you remove your thumb Remove your finger, observing what happens Repeat the experiment, only next time, milk the vein toward your hand…now what happens? How many valves can you locate?

13. CAPILLARIES: Gas Exchange Nutrient Delivery Waste Removal A Whole lot of Diffusion Going On…

14. Capillaries: Structure/Function Function: Diffusion/Osmosis! Endothelium: Single epithelial (squamous) cell thick Lumen: Just big enough to allow passage of Red Blood Cells Blood flow affected by: Pre-capillary sphincter/Arterioles Surrounding tissues

15. Terms to Know: Vessel Layers: Tunica Adventitia (Externa): Connective tissue surrounding vessel Tunica Media: Elastic Connective tissue and Smooth Muscle Tunica Intima: Basement membrane and endothelium

16. More Terms: Vasoconstriction: Contraction of vascular smooth muscle to narrow the vessel lumen Increases Vascular Resistance Vasodilation: Relaxation of vascular smooth muscle to increase the diameter of vessel lumen Decreases Resistance

17. Pressure and Perfusion… Physiology of Circulation Systolic Pressure: Highest arterial pressure following ventricular systole Must be high enough to adequately perfuse vital tissues (generally >100 mmHg)

18. Pressure and Perfusion: Diastolic Pressure: Lowest arterial pressure during ventricular diastole The pressure in arteries when they are fully open The higher the pressure, the smaller the collective arterial vessel bed Which leads us to…

19. Total Peripheral Resistance: (More terms) Resistance: Any impedance of blood flow – usually by narrow or inelastic vessels Total Peripheral Resistance: The collective sum of the entire arterial vascular bed resistance.

20. TPR: Effect on Perfusion Increased Resistance (TPR): Increases the work of the heart and ultimately heart failure Causes a greater drop in blood pressure (perfusion) DOWNSTREAM possibly causing tissue ischemia (inadequate oxygen)

21. Final Terms: Conducting Vessels : Arteries that are very elastic (low resistance) and transmit blood flow without a large drop in pressure Resistance Vessels : Arterioles that are active in directing blood flow by selective vasoconstriction resulting in the largest drop in arterial pressure

22. Exercise Application: Exercise Training increases Maximum Oxygen Consumption VO 2 Peak

23. Where is that happening? Oxygen Delivery: O 2 Exchange and Carrying capacity (Lungs/RBC) = Blood Cardiac Output Delivery: More blood flow to muscles Oxygen Uptake: Increased a-vO 2 Difference

24. a-vO2 Difference: The measured difference in O 2 content between the arterial (delivery) and venous (removal) circulation An indication of O 2 consumption by the working tissues (more O 2 =more work) VeinsArteries O2 extracted by mitochondria 20 ml O215ml O2

25. Training Increases the a-vO 2 Difference Increases Cellular oxidative capacity: More mitochondria and oxidative enzymes Increases Working tissue mass and the capillary network feeding it… More oxygen delivery