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The Cardiovascular System: The Blood Vessels and Circulation
Brady Anatomy and Physiology for Emergency Care 2nd Edition Chapter 11
32
Anatomy
Professional
02/17/2012

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Term
Arteries
Definition
-distribute blood to body organs
-pulmonary trunk and aorta
Term
Arterioles
Definition
-first branches of arteries, slightly smaller.
-provide blood to capillaries
Term
Capillaries
Definition
-barely the diameter of a single red blood cell
-form extensive branching networks
-chemical and gaseous exchange between the blood and interstitial fluid takes place across capillary walls.
-tissue cells rely on capillary diffusion to obtain nutrients and oxygen and to remove metabolic wastes
-the ONLY blood vessels whose walls permit exchange between blood and the interstitial fluid.
-diffusion distances are small, exchange occurs quickly
Term
Venules
Definition
-blood moves out of the capillary network and first enters the venules
-smallest vessels of the venous system.
Term
Veins
Definition
-Venules merge to combine veins.
-blood passes through small veins then medium and large veins before reaching the vena cava (in the systemic circuit) or the pulmonary veins (in the pulmonary circuit)
-collect blood from all tissues and return it to the heart
Term
Tunica interna
Definition
-innermost layer of blood vessels
-endothelial lining
Term
Tunica media
Definition
-middle layer
-contains smooth muscle tissue
-thicker in arteries to resist pressure created by the heart as it forces blood into the arterial network
Term
Tunica externa
Definition
-forms sheath of connective tissue around the vessel
-anchors the vessel
Term
Vasoconstriction
Definition
-arterial smooth muscle under the control of the sympathetic division of the autonomic nervous system
-muscles in the vessel wall constricts
Term
Vasodilation
Definition
-relaxation increases the diameter and its central opening (lumen)
Term
Capillary beds
Definition
-interconnected network of capillaries
Term
Precapillary sphincter
Definition
-band of smooth muscle at the entrance of each capillary
Term
Vasomotion
Definition
-blood flow within any capillary is intermittent rather than a steady stream because each capillary sphincter undergoes cycles of activity between contracting and relaxing each minute
Term
Autoregulation
Definition
-tissue smooth muscle fibers respond to local changes in the concentration of chemicals and dissolved gases in interstitial fluid to allow for blood flow into the capillary sphincters
Term
Anastomosis
Definition
-blood vessels provide alternate routes for blood flow by joining two tubes.
Term
Ateriovenous anastomosis
Definition
-a vessel that connects an arteriole to a venule.
Term
Vein valves
Definition
-in medium-sized veins
-prevent back-flow of blood returning to the heart
Term
Circulatory pressure
Definition
-largest pressure gradient found between the base of the aorta and the entrance to the right atrium
-averages about 100mmHg
-divided into arterial pressure, capillary pressure and venous pressure
Term
Resistance
Definition
-any force that opposes movement
-greatest pressure resistance is in the arterial network between arteries and arterioles (65 mmHg)
-peripheral resistance
Term
Vascular resistance
Definition
-resistance of the blood vessels to blood flow
-most important factor in vascular resistance is friction between the blood and the vessel walls.
-the amount of friction depends on the length and diameter of the vessel.
-friction increases with length and decreasing vessel diameter
Term
Viscosity
Definition
-the resistance to flow that results from interactions among molecules and suspended materials in a liquid.
-blood has a viscosity about 5 times that of water.
Term
Anemia
Definition
-reduced hematocrit due to inadequate production of hemoglobin, RBCs or both
-as a result blood viscosity and the oxygen-carrying capacity of the blood are reduced
Term
Turbulence
Definition
-high flow rates, irregular surfaces caused by injury or disease processes or sudden changes in vessel diameter upset smooth flow and increases resistance.
Term
Systemic pressure
Definition
-highest in the aorta (120 mmHg)
-lowest in the venae cavae (2 mmHg)
Term
Systolic pressure
Definition
-the peak blood pressure measured during ventricular systole
Term
Diastole
Definition
-the minimum pressure at the end of ventricular diastole
Term
Pulse pressure
Definition
-difference between systolic and diastolic blood pressure
Term
Capillary pressure
Definition
-pressure of blood within a capillary bed.
Term
Capillary exchange
Definition
-continuous movement and exchange of water and solutes from the capillaries through the body tissues and back into the bloodstream
-important role in homeostasis
-4 functions
-maintain constant communication between plasma and interstitial fluid
-speed the distribution of nutrients, hormones, and dissolved gases throughout tissue
-assist movement of insoluble lipids and tissue proteins that cannot cross capillary walls
-flushing bacteria toxins and other chemical stimuli to lymphoid tissues and organs that function in providing immunity to disease
Term
Muscular compression
Definition
-contractions of skeletal muscles near a vein compress it and help push blood toward the heart
Term
Respiratory pump
Definition
-inhalation causes decreased pressure in the thoracic cavity and causes the inferior vena cava and right atrium to expand and fill with blood
-exhalation increases pressure in the thoracic cavity compresses the venae cavae, pushing blood into the right atrium
Term
3 factors that influence tissue blood flow
Definition
-cardiac output
-peripheral resistance
-blood pressure
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