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Human Anatomy and Physiology Unit IV Circulation and Body Defense Part III Blood Vessels
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Blood Vessel Topics Components of the blood vessel system
Basic structures of blood vessels Blood distribution Capillary exchange Factors affecting blood pressure and flow Control of blood pressure and flow Circulatory routes
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Components of the Blood Vessel System
The circulatory system is composed of arteries, arterioles, capillaries, venules, and veins
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Components of the Circulatory System
Heart Arteries Arterioles Capillaries Venules Veins
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Blood Vessel Topics Components of the blood vessel system
Basic structures of blood vessels Blood distribution Capillary exchange Factors affecting blood pressure and flow Control of blood pressure and flow Circulatory routes
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Basic Blood Vessel Structure
Specializations of the blood vessel wall gives different types of vessels their unique functions
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Basic Blood Vessel Structure
Tunica Interna Endothelium Basement membrane Internal elastic lamina Tunica Media Smooth muscle External elastic lamina Tunica Externa Connective tissue
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Figure 21.1Comparative structure of blood vessels
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Arteries Elastic Well-defined elastic laminae
Thick tunica media dominated by elastic fibers Act as pressure reservoirs Muscular Well-defined internal elastic lamina but thin external elastic lamina Thick tunica media dominated by smooth muscle Maintain vascular tone
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Figure 21.2 Pressure reservoir function of elastic arteries
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Figure 21.2 Pressure reservoir function of elastic arteries
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Elastic Artery 21_01d
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Muscular Artery 21_01d
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Arterioles Poorly defined internal elastic lamina
Thin layer of smooth muscle forming precapillary sphincter Well-innervated tunica external Control blood flow into capillary beds
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Figure 21.3 Arterioles, capillaries, and venule
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Figure 21.3 Arterioles, capillaries, and venule
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Capillaries Microscopic; smallest vessels in body
Tunica interna: endothelium and basement membrane Tunica media: None Tunica externa: None Permit exchange of nutrients and wastes between blood and interstitial fluid; distribute blood to postcapillary venules
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Figure 21.3 Arterioles, capillaries, and venule
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Figure 21.1Comparative structure of blood vessels
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Types of Capillaries Three types Continuous – leaky; muscle, CT, lungs
Fenestrated – leakier; kidneys, sm. Intestine, brain, eye, endocrine glands Sinusoids – leakiest; liver, red bone marrow, spleen
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Figure 21.4 Anatomy of a continuous capillary
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Figure 21.4 Anatomy of a fenestrated capillary
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Figure 21.4 Anatomy of a sinusoidal capillary
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Figure 21.3 Arterioles, capillaries, and venule
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Venules Microscopic Tunica interna: endothelium and basement membrane
Tunica media: 1-2 layers of smooth muscle Tunica externa: Sparse Pass blood into veins; act as blood reservoirs
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Figure 21.3 Arterioles, capillaries, and venule
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Veins Range from 0.5mm-30mm Tunica interna: endothelium and basement membrane; no internal elastic lamina; contains valves; large lumen Tunica media: Much thinner than in arteries; no external elastic lamina Tunica externa: Thickest of three layers Return blood to heart
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Figure 21.5 Venous veins 21_05
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Blood Vessel Topics Components of the blood vessel system
Basic structures of blood vessels Blood distribution Capillary exchange Factors affecting blood pressure and flow Control of blood pressure and flow Circulatory routes
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Blood Distribution Because systemic veins and venules contain more than half the total blood volume, they are called blood reservoirs
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Figure 21.6 Blood distribution in the cardiovascular system
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Blood Vessel Topics Components of the blood vessel system
Basic structures of blood vessels Blood distribution Capillary exchange Factors affecting blood pressure and flow Control of blood pressure and flow Circulatory routes
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Capillary Exchange Blood hydrostatic pressure pushes fluid out of capillaries (filtration), and blood colloid osmotic pressure pulls fluid into the capillaries (reabsorption)
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Figure 21.7 Capillary exchange
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Blood Vessel Topics Components of the blood vessel system
Basic structures of blood vessels Blood distribution Capillary exchange Factors affecting blood pressure and flow Control of blood pressure and flow Circulatory routes
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Blood Flow BF= CO; (SV X HR) The same factors that change CO change BF
Stroke volume: preload and contractility Heart rate: nervous system and chemicals
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Figure 21.8 21_08
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Figure 21.9 21_09
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Figure 21.10 21_10
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Figure 21.11 21_11
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