Chapter 29 Flashcards
Nearly ______ km of blood vessels carry blood throughout the body
100,000
Angiogenesis
Formation of blood vessels begins during embryonic development and continues throughout life
Types of blood vessels (3)
Arteries, capillaries, veins
Arteries
carry blood away from the heart ventricles
All carry oxygenated blood EXCEPT pulmonary artery
aorta is largest one arteries (elastic and muscular) arterioles metarterioles that end at precapillary sphincters that wrap around entrance to capillaries (controls blood flow in to capillary beds)
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Capillaries
Microscopic blood vessels = microcirculation
site of gas and nutrient exchange between blood & tissue fluid around cells (capillary beds/networks); over 1 billion with highest concentration in tissues with high metabolic rate
connect arteries and veins via arterioles and venules
Veins
carry blood toward the heart atria
superior and inferior vena cava are the largest ones
Capillary beds/networks venules veins vena cava
Microcirculation
Heart-> aorta-> arteries-> arterioles-> capillary bed/network-> venules-> veins-> superior vena cav-> heart
4 types of materials that make up the wall of blood vessel
Endothelial tissue/ endothelium (lining)
Collagen fibres
Elastic fibres
Smooth muscle tissue
Endothelial tissue/ endothelium
Provides the lumen of blood vessels with a smooth surface, thereby influencing blood flow and intravascular blood clotting
A special type of simple squamous epithelium; allows for exchange of gases, nutrients, and other substances
Intercellular clefts between the cells and ‘fenestrations’ dictate movement of substances in and out of the blood vessel (See Figure in Textbook)
Collagen fibers
Provide blood vessels with strength and some flexibility (much less than elastic fibres)
Function to keep the lumen of blood vessels open
Strengthen blood vessels walls
Elastic fibres
Made of a protein polymer called ‘elastin’ - can stretch more than 100% when at work in the body
Arranged concentrically in large elastic arteries, allowing for distention and recoiling
Maintain passive tension of blood vessels for normal blood pressure
Smooth muscle tissue
Found in the wall of all blood vessels EXCEPT capillaries
Highest concentration is in elastic and muscular arteries contraction active tension
Tunica intima
Inner layer
Single layer of squamous epithelial cells (endothelium- lines entire surface of circulatory system)
One way valves
Tunica media
Middle layer
Smooth muscle with a thin layer of elastic tissue
Thicker in arteries than veins (to withstand systole)
Important in BP regulation (smooth muscle – ANS)
Tunica adventitia/externa
Outermost layer/collagen fibres
Reinforces wall of vessel to withstand pressure
Thicker in artery than in veins