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Compliments of Gary Larson

Pre-Lab Lecture. Compliments of Gary Larson. Blood Vessels and Circulation. Chapter 13. Peripheral Circulation:. Systemic Circulation: Blood vessels directing blood to the body tissues Left Heart to Right Heart Pulmonary Circulation:

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Compliments of Gary Larson

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  1. Pre-Lab Lecture Compliments of Gary Larson

  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: • O2/CO2, Energy substrates, Minerals, H2O 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 O2 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 O2 – 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 • VO2 Peak

  23. Where is that happening? • Oxygen Delivery: • O2 Exchange and Carrying capacity (Lungs/RBC) = Blood • Cardiac Output • Delivery: More blood flow to muscles • Oxygen Uptake: • Increaseda-vO2 Difference

  24. a-vO2 Difference: • The measured difference in O2 content between the arterial (delivery) and venous (removal) circulation • An indication of O2 consumption by the working tissues (more O2=more work) 20 ml O2 15ml O2 Arteries Veins O2 extracted by mitochondria

  25. Training Increases the a-vO2 Difference • Increases Cellular oxidative capacity: • More mitochondria and oxidative enzymes • Increases Working tissue mass and the capillary network feeding it… • More oxygen delivery

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