ExamIII notes - Exam III will be based mainly on Lecture...

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Exam III will be based mainly on Lecture material (nothing from the book not in the lecture) March 27, 2008 Chapter 19: The Cardiovascular System: Blood Vessels pages 713-742 [Sections 1&2 of this chapter] A. The Blood Vessels a. Form a closed system [or nearly closed because in capillary system there is exchange and fluid can be lost] b. 3 major types i. Artery: carries blood away from the heart 1. always carry blood away from heart, but doesn’t always carry oxygenated blood ii. Capillary: exchange nutrients and waste 1. takes place in capillary beds iii. Vein: carries blood toward the heart 1. always carry blood toward the heart 2. not always deoxygenated blood [in pulmonary circuit, veins carry oxygenated blood] c. heart is a pressure pump B. Generalized Structure of Blood Vessels a. Vessels are made of 3 tunics i. Tunica intima: lines lumen wall 1. [intimate] comes in contact with blood 2. lumen = hollow space inside vessels where blood travels 3. squamous epithelial cells [aka endothelium] 4. subendothelial layer = basement membrane [connective tissue layer at basal layer of epithelial cells, connects to adjacent layer (tunica media)] 5. cells bound tightly together to prevent leakage 6. slick smooth surface to minimize friction 7. laminar flow = smooth flow 8. vessels>1mmdiameter ii. Tunica media: thickest layer 1. body senses stress and pressure, which causes endothelial cells to be activated, secreting nitric oxide (laughing gas); potent vasodilator 2. smooth muscle with elastin connective tissue (allows it to stretch and return to normal shape/size) – long continuous groups of these cells 3. vasoconstriction (lumen/radius gets smaller)/vasodilation (increase in size of lumen/radius increases) – this is how we regulate blood fluid by regulating size of the lumen. 4. ^regulated by vasomotor nerve from ANS
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5. sympathetic fibers come down and innervate these vessles (particularly the large vessels) –receptors that are sensitive to norepinephrine [causes someone to go pale when they are nervous/stressed] iii. Tunica externa- outermost layer 1. loose collagen connective tissue 2. nerves and lymph vessels 3. vasa vasorum- a. vessels of the vessels [blood vessels have their own blood vessels] b. diagram – i. tunica adventitia = tunica externa C. Vascular Components – figure 19.2a-b a. Diagram i. arterioles are constricted while we sit and do nothing, but when we stand up and start walking, the arterioles will dilate and allow blood flow to increase in the regions. Arterioles control where the blood goes = resistance vessels. b. Anastomoses = a network of streams that both branch out and reconnect i. Alternate pathways (collateral channels/vessels) ii. Thoroughfare channels are examples of arteriovenous anastomoses c. Pie chart that shows amt of blood in different portions: i. Heart = 8% --when it pumps out blood, blood goes to pulmonary and systemic circuits ii. Capillaries = 5% iii. Systemic circuit = 15% iv.
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ExamIII notes - Exam III will be based mainly on Lecture...

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