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Across 2. Type of vessel which carries blood toward the heart 4. The __________ pump is when body movement helps venous blood return to the heart 5. Area of lowest blood pressure within the body 10. Middle layer of the blood vessel, with a layer of smooth muscle to control vessel diameter 12. Ability of a compartment within the body to expand and accommodate increased content 13. Small veins leading from the capillary bed 16. Area of highest blood pressure within the body 19. Connective tissue on the outside of a vessel, functioning to anchor and protect the vessel 22. Decreasing the diameter of a vessel, to reduce flow and increase pressure 23. Area of the brain which controls blood vessel diameter 24. Type of vessel which carries blood away from the heart 25. The __________ pump is when breathing helps venous blood return to the heart 26. Smallest blood vessels and the site of gas exchange 27. Increasing the diameter of a vessel, to increase flow and reduce pressure 28. Type of capillary with extensive gaps to allow passage of large molecules

Down 1. Most numerous type of capillaries with only very small gaps to allow substance movement 2. Describes the thickness of a fluid 3. Innermost layer of the blood vessel, functions to reduce friction with blood 6. Receptors which monitor oxygen and carbon dioxide in the blood 7. Majority of smaller arteries in the body 8. Type of capillary with pores to allow greater permeability 9. Central space within the blood vessel 11. Measurement of force exerted by the blood on the wall of a vessel 14. Measurement of the opposition to flow as blood moves through a vessel 15. Many veins contain _________ _________ to maintain forward blood movement 17. Thick walled arteries near the heart which are able to maintain blood pressure when heart ventricles relax 18. Receptors which are activated by blood pressure in the elastic arteries 20. Measurement of the blood flowing through a vessel in a certain amount of time 21. Small arteries which lead to the capillaries