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Chapter 22: The Cardiovascular System
Vessels and Circulation
31
Anatomy
Undergraduate 1
12/11/2011

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Term
What are the three distinct layers that make up the walls of arteries and veins?
Definition
  1. tunica intima (interna)
  2. tunica media
  3. tunica externa (adventitia)
Term
tunica interna (intima)
Definition
the innermost layer of a blood vessel
Term
tunica media
Definition
middle layer, contains concentric sheets of smooth muscle tissue in a framework of loose conective tissue
Term
smooth muscle tissue in tunica media
Definition
under control of the sympathetic division of the ANS: vasoconstriction and vasodilation
Term
vasoconstriction
Definition
smooth muscles contract and reduce the diameter of the blood vessel
Term
vasodilation
Definition
relaxation of the smooth musces increases the diameter of the lumen
Term
tunica externa (adventitia)
Definition
forms a connective tissue sheath around the vessel
Term
large elastic arteries
Definition
  • transport large volumes of blood away from the heart
  • ex: pulmonary and aortic trunks and their major branches
  • extremely resilient
Term
aortic aneurysm
Definition
swelling of the aorta due to weakness of the aortic wall at some location
Term
muscular arteries
Definition
  • distribution arteries, transport blood to the body's skeletal muscle and internal organs
  • ex: external carotid, brachial arteries, femoral arteries, mesenteric arteries of the abdomen
  • ANS control diameter of these
Term
Arterioles
Definition
  • smaller than muscular arteries
  • control the blood flow between arteries and capillaries
Term
Capillaries
Definition
  • smallest and most delicate blood vessels
  • diffusion and exchange occur quickly
  • 3 types
Term
What are the 3 types of capillaries?
Definition
  1. continuous capillaries
  2. fenestrated capillaries
  3. sinusoids
Term
continuous capillaries
Definition
found in most regions of the body
Term
fenestrated capillaries
Definition
contain "windows" or pores in their walls which permits rapid exchange of fluids and solutes
Term
sinusoids
Definition
have larger pores and thinner basal lamina which blood moves through relatively slow maximizing time for absorption and secretion
Term
capillary beds/plexus
Definition
concentration of capillaries; direct connections between arterioles and venules
Term
list the arteries from largest to smallest
Definition
  1. large elastic arteries
  2. muscular arteries
  3. arterioles
  4. capillaries
Term
veins
Definition
collect blod from all tissues and organs and return it to the heart
Term
venules
Definition
the smallest veins collect blood from the capillaries
Term
medium-sized veins
Definition
larger than venules but smaller than large veins
Term
large veins
Definition
include the great veins, superior and inferior vena cava and their tributaries within abdominopelvic and thoracic cavities
Term
What are all the veins from smallest to largest?
Definition
  1. capillaries
  2. venules
  3. medium-sized veins
  4. large veins
Term
venous valves
Definition
  • one-way valves that are formed from infoldings of the tunica intima
  • prevent the backflow of blood
  • skeletal muscle pump
Term
skeletal muscle pump
Definition
any movement in the surrounding skeletal muscles squeezes the blood toward the heart
Term
T/F: the blood volume is evenly distributed among arteries, veins, and capillaries
Definition

FALSE

unevenly distributed

heart, arteries, capillaries: 30-35% of blood volume

venous system: 65-70% of blood volume

(because venous walls are thinner and more distensible than arteries)

Term
What happens if the body begins hemorrhaging?
Definition
the medulla oblongata stimulates sympathetic nerves innervating smooth muscle cells in the walls of medium-sized veins reducing the volume of the venous system and maintaining the volume within the arterial system at near-normal levels despite blood loss
Term
blood reservoir
Definition
the venous system acts as this with the liver acting as the primary reservoir
Term
carotid body
Definition
  • cluster of chemoreceptors
  • detect changes in:
    • partial pressure of O2 & CO2
    • pH and temperature
Term
hepatic portal system
Definition
  • liver is the only digestive organ drained by the inferior vena cava
  • blood that absorbs nutrients flows directly to the liver for processing and storage
  • blood in hepatic portal system therefore has levels of blood glucose and amino acids higher than anywhere else in the circulatory system
Term
thrombus
Definition
stationary blood clot
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