CH. 4 VASCULATURE

  1. what does the term Vasculature mean?
    collective term that refers to all of the blood vessels of the body.
  2. The blood vessels that compromise the vasculature transport blood from the heart to the cells of the body and then back to the heart are....
    heart -> arteries -> arterioles -> capillaries -> venules -> veins
  3. altogether, blood travels through how many miles of blood vessels?
    60,000 miles
  4. what are the components of  the vasculature?
    • 1. arteries 
    • 2. arterioles
    • 3. capillaries
    • 4. venules 
    • 5. veins
  5. what is the structure of an artery consist of,
    • 1. tunica externa 
    • 2. tunica media
    • 3. tunica interna
  6. what is the function of arteries?
    arteries carry oxygenated blood from the heart to arterioles.
  7. describe the tunica externa ...
    • outer layer 
    • connective tissue that is composed of collagen fibers & elastic fibers
  8. describe the tunica media...
    • middle layer
    • consists of... smooth layer & external elastic lamina
  9. in  the tunica media, 
    what is external elastic lamina composed of?
    connective tissue that is composed of elastic fibers.
  10. describe the tunica interna
    • inner layer
    • consists of, 
    • 1. endothelium 
    • 2. basement membrane 
    • 3. internal elastic lamina
  11. what is the endothelium in the tunica media?
    • single layer of epithelial cells 
    • surrounds the lumen, which is the hollow space where the blood is located.
  12. what does the term endothelium always refer too?
    the epithelial cells that line the lumen of a blood vessel or a lymphatic vessel.
  13. what is the basement membrane and where is it located?
    • a thin layer of connective tissue that is composed of collagen fibers.
    • located in the tunica interna
  14. what is the internal elastic lamina?
    and where is it located?
    • connective tissue that is composed of elastic fibers 
    • located in the tunica interna
  15. structure of arterioles
    • an intermediate between that of an artery & a capillary
    • hence, an arteriole contains an inner layer of endothelium, a middle layer of basement membrane, and and outer layer of smooth muscle.
  16. function of arterioles
    carry oxygenated blood from the arteries to the capillaries.
  17. most numerous type of blood vessel?
    & how many of them exist?
    • capillaries
    • about 10 billion of them exist in body.
  18. most cells in the body are located near atleast one what?
    capillary, sense they are so numerous.
  19. there is an exemption to the distribution of blood via capillaries, what are they? (ograns, parts of the body that lack capillaries
    • epithelia, cartilage, and the lens of the eye
    • these are Avascular (i.e. these tissues lack capillaries)

  20. how do the Epithelial and cartilage receive nutrients if they are avascular and do not contain capillaries?
    receive nutrients via diffusion from nearby connective tissue
  21. how do the cornea and lens receive nutrients if they are avascular and do not contain capillaries?
    receive nutrients via diffusion from the aqueous humor
  22. what do capillaries do?
    and how is the accomplished?
    • connect arterioles to venules
    • in order for this to be accomplished, capillaries interact with one another to form capillary beds
  23. what are the 2 major types of vessels that make up a capillary bed ?
    • capillaries
    • metarteriole
  24. what is a metarteriole ?
    • a blood vessel that branches off of an
    • arteriole, it courses through the capillaries, and then empties into a
    • venule
  25. what is the distal end of the metarteriole called?
    thoroughfare channel.
  26. The metarteriole functions as a..

    and what does it do?
    vascular shunt that bypasses the capillaries when the body cells near the capillaries are not in need of any nutrients.
  27. Around the junction of the metarteriole and the capillaries are rings of smooth muscle called? 
    and what do they do?
    • precapillary sphincters
    •  function to regulate blood flow into the capillaries.
  28. When the precapillary sphincters are open (i.e. the smooth muscle is relaxed), what happens?
    blood flows into the capillaries and into the metarteriole.
  29. in what cases do precapillary sphincters open?
    when nearby body cells are in need of nutrients (i.e. O2, glucose, etc).
  30. When the precapillary sphincters are closed (i.e. the smooth muscle is contracted), what happens?
    blood flows only into the metarteriole and bypasses the capillaries.
  31. in what cases do the  precapillary sphincters will be closed?
    when nearby body cells are satisfied with existing nutrient supplies and are no longer in need of any more blood.
  32. A capillary is a microscopic blood vessel that consists of 2 layers, what are they?
    • endothelium
    • basement membrane
  33. endothelium in the capillaries, 
    # of layers and its pores?
    • single layer of epithelial cells
    • endothelium of many capillaries contains pores (holes) in the form of intercellular clefts and fenestrations.
  34. intercellular clefts, where are they located?
    endothelium of capillaries and pores that exist between the endothelial cells of a capillary
  35. fenestrations, where are they located?
    endothelium of capillaries, pores that run through individual endothelial cells of a capillary
  36. what is the basement membrane of the capilarries?
    basement membrane of capillaries is also porous, but these pores have no specific names.
  37. Capillaries are the only blood vessels that permit the exchange of what?
    gases, nutrients, and wastes between the blood and the cells of the body, transforming oxygenated blood into deoxygenated blood.
  38. what moves between the capillaries and the body cells down their gradients by diffusion?
    Only small to moderately-sized molecules (such as gases, H2O, ions, glucose, amino acids, and hormones) are able to
  39. what typically diffuse across the lipid bilayer of the endothelial cells of capillariesjQuery112405365050676703276_1528290516169
    Hydrophobic substances (O2, CO2, steroid hormones, and thyroid hormones) and small uncharged hydrophilic molecules (like water)
  40. must diffuse through the pores of the capillary
    Moderately-sized uncharged hydrophilic molecules (such as glucose) and most charged hydrophilic molecules (such as ions and amino acids)
  41. are too large to diffuse through the pores and are therefore confined to the blood.
    All cells and most plasma proteins (albumins, fibrinogen, etc.)
  42. All cells and most plasma proteins (albumins, fibrinogen, etc.) are too large to diffuse through the pores EXCEPT!jQuery112405045335308587573_1528317020357?
    include protein hormones which are small enough to pass through the pores of the capillaries to bind to specific receptors on their target cells.
  43. H2O that diffuses out of the blood into the interstitium (the spaces between and around body cells) is calledjQuery112407099451672962733_1528334268486 (capillary)
    interstitial fluid (ISF)
  44. interstitial fluid is a type of extracellular fluid located wherejQuery112405861846996599138_1528374785345 (capillaries)
    between and around body cells
  45. if interstitial fluid is a type of extracellular fluid located between and around body cells, what is  blood ??? (capillary)
    blood is a type of extracellular fluid located within blood vessels.
  46. H2O in the interstitial fluid can diffuse into???
    body cells if needed.
  47. what happens If there is too much H2O in the interstitium?? (capillary)
    the excess interstitial fluid drains into a nearby lymphatic vessel (usually a lymphatic capillary) that transports the fluid back into the blood.
  48. what is the structure of a venule like?
    • is intermediate between that of a capillary
    • and a vein
  49. what are the layers of a venule?
    • contains an inner layer of endothelium,
    • a middle layer of basement membrane, and a thin, outer layer of smooth muscle
  50. what is the function of a venule?
    transport deoxygenated blood from the capillaries to the veins
  51. what is the structure of a vein like? what layers does it consist of?
    • tunica externa
    • tunica media
    • tunica interna
  52. what is the tunica externa in a vein?
    what it is made of?
    is it thicker or thinner?
    • its the outer layer
    • connective tissue that is composed of collagen fibers and elastic fibers
    • tunica externa of a vein is thinner than the tunica externa of an artery
  53. why is the tunica externa of a vein thinner than that of an artery?
    because it contains less connective tissue
  54. what is the tunica media of a vein?
    what does it consist of?
    is it thinner or thicker than that of artery?
    • it is the middle layer
    • consists of smooth muscle
    • thinner
  55. why is the tunica media thinner than the tunica media of arteries?
    because it has less smooth muscle.
  56. what is the tunica interna of an vein?
    what does it consist of?
    • it is the inner layer
    • 1. endothelium
    • 2. basement membrane
  57. what blood vessel contains valves?
    • veins
    • many veins of the limbs contain valves
  58. what is a venous valve?
    and what does is do?
    consists of folds of the tunica interna that function to prevent backflow of blood.
  59. so how does flow of blood occur in veins?
    • Contractions of skeletal muscles surrounding the veins help push blood up the veins 
    • the valves prevent backflow of blood, making sure that the blood returns to the heart
  60. what is vital to the process of venous
    return
    skeletal muscle pump
  61. what is advisable to do any time that you have to stand for a long periods of time?
    what happens if you don't?
    • periodically contract the muscles in your legs in order to make sure that blood goes back to the heart
    • otherwise, blood may pool in the veins and you may pass out since the heart is not able to pump enough blood to the brain.
  62. what is the function of veins?
    Veins transport deoxygenated blood from venules to the heart.
  63. Comparison of an Artery and a Vein
    • Artery
    • tunica externa- more connective tissue
    • tunica media- more smooth muscle
    • tunica interna- lacks valves
    • overall appearance- round; thick wall
    • Vein
    • tunica externa- less connective tissue
    • tunica media- less smooth muscle
    • tunica interna- contains valves (especially in the limbs)
    • overall appearance- thin wall; often collapsed
  64. Alteration of Blood Vessel Diameter
    Most blood vessels (arteries, arterioles, veins, and venules) can change their diameters by....?
    contracting or relaxing the smooth muscle in their walls
  65. what happens when a blood vessel undergoes vasoconstriction??
    the smooth muscle within its wall contracts
  66. what happens when the blood vessel lumen becomes smaller?
    causes a reduction of blood flow.
  67. what happens when a blood vessel undergoes vasodilation?
    • the smooth muscle within its wall relaxes
    • Consequently, the blood vessel lumen becomes wider, which causes an increase in blood flow.
  68. only blood vessels that do not vasoconstrict or vasodilate
    and why?
    • capillaries
    • this is due to the fact that capillaries lack smooth muscle in their walls.
  69. capillaries have no smooth muscle around it, but there is an exception. what part of the capillary does contain smooth muscle?
    smooth muscle that forms the precapillary sphincters located between metarterioles and capillaries
  70. what does the smooth muscle in the precapillary sphincters do?
    can constrict or dilate in order to regulate blood flow through the capillary
  71. Blood Distribution.Cardiovascular Component
    of (%)
    HEART
    7 %
  72. Blood Distribution.Cardiovascular Component
    of (%)
    SYSTEMIC ARTERIES AND ARTERIOLES
    13%
  73. Blood Distribution.Cardiovascular Component
    of (%)
    SYSTEMIC CAPILLARIES
    7%
  74. Blood Distribution.Cardiovascular Component
    of (%)
    SYSTEMIC VEINS & VENULES
    64%
  75. Blood Distribution.Cardiovascular Component
    of (%)
    PULMONARY BLOOD VESSELS
    9%
  76. where is most of the blood volume at any given time?
    systemic veins and venules
  77. consequently, systemic veins and venules are called the??
    blood reservoirs of the body
  78. what happens in cases of a blood shortage?
    blood can be can be mobilized from the veins and venules and sent to the other parts of the body that need it
  79. Vascular Compliance
    -Compliance means ????
    give an example
    • the ability of an object to stretch
    • rubber band
    • -has a high compliance because it can be easily stretched
    • crowbar
    • -used to change a tire
    • -has a low compliance because it is not easily stretched
  80. what kind of compliance do veins have? and why?
    Veins have a high compliance because they contain thin walls that are easily stretched
  81. what are veins called because they have a high compliance ??
    the capacitance elements
  82. Because veins are so highly compliant, an increase in the blood volume of veins simply stretches their walls and what happens??
    • it allows blood to pool in the veins; this is why veins contain the majority of the
    • blood volume of the body
  83. because veins are so compliant, the increase in the blood volume of veins simply stretch the wall and it allows what ??
    allows blood to pool in the veins; this is why veins contain the majority of the blood volume of the body
  84. what happens to the venous volume and venous pressure because of the veins high compliance?
    means that an increase in venous volume is converted to stretch rather than a significant increase in venous pressure.
  85. So, even though veins contain the majority of blood in the body, venous pressure is...
    very low (typically near 0 mm Hg in the large great veins like the inferior vena cava and superior vena cava).
  86. what kind of compliance does the arteries have and why?
    low compliance compared to veins because arteries contain thick walls that are not as easy to stretch.
  87. what does the increase in blood volume of arteries cause (do to its low compliance)
    causes an increase in arterial pressure because the arteries cannot stretch as much as the veins
  88. what is the arterial pressure like?
    arterial pressures are typically high, varying between 110 mm Hg and 70 mm Hg.
  89. what is blood pressure?
    the pressure that blood exerts on the walls of a blood vessel
  90. how is blood pressure usually measured ???
    in the brachial artery using a device called the sphygmomanometer
  91. Blood pressure in any major artery of the body varies between what?
    the systolic pressure and the diastolic pressure
  92. what is systolic pressure?
    & what does it measure?
    • the maximum pressure exerted by blood on arterial walls during ventricular systole
    • -normally equals about 110 mm Hg
  93. what is diastolic pressure?
    & what does it measure?
    • the minimum pressure exerted by blood on arterial walls during ventricular diastole
    • -normally equals about 70 mm Hg
  94. how is blood pressure generally written as?
    blood pressure= systolic pressure/diastolic pressure
  95. what is Blood pressure under normal circumstances?
    110/70 mm Hg
  96. what are factors that affect blood pressure?
    blood pressure is affected by changes in stroke volume, heart rate, cardiac output, and blood vessel diameter (vasoconstriction or vasodilation).
  97. An increase in stroke volume and/or heart rate causes an increase in cardiac output so what does that mean?
    The increase in cardiac output means that more blood is ejected from the heart, which causes an increase in blood pressure due to the excess blood pushing on the walls of the blood vessels of the body
  98. what does vasoconstriction do to our blood pressure?
    causes an increase in blood pressure since blood pushes more on blood vessel walls due to the smaller volume of the blood vessels.
  99. A decrease in stroke volume and/or heart rate causes a decrease in cardiac output, what does that mean?
    decrease in cardiac output means that less blood is ejected from the heart, which causes a decrease in blood pressure due to less blood pushing on blood vessel walls.
  100. what does vasodilation do our blood pressure?
    causes a decrease in blood pressure since blood does not push as much on blood vessel walls due to the larger volume of the blood vessels.
  101. what is Neural Regulation of Blood Pressure
    Blood pressure is regulated via a negative feedback system that involves the cardiovascular center.
  102. what is located in the medulla, which is part of the brainstem
    cardiovascular center
  103. gives rise to the parasympathetic (Vagus) nerves that innervate the heart
    (outout)
    Part of the cardiovascular center
  104. the stimulation of parasympathetic (Vagus) nerves cause what in the heart rate?
    (output)
    stimulation of these nerves causes a decrease in heart rate
  105. The cardiovascular center also makes connections with which are sympathetic nerves?
    (output)
    makes connections with the cardiac accelerator nerves, which are sympathetic nerves that innervate the heart.
  106. stimulation of the cardiac accelerator nerves does what ??
    (output)
    stimulation of these nerves causes an increase in heart rate and an increase in ventricular contraction (stroke volume).
  107. cardiovascular center also has connections with the vasomotor nerves, what are the vasometer nerves?
    (output)
    are sympathetic nerves that innervate the smooth muscle in the walls of the blood vessels of the body (except the capillaries).
  108. Stimulation of the vasometer nerves cause what ?
    (output)
    causes vasoconstriction of most blood vessels in the circulation
  109. The cardiovascular center receives input via what??
    baroreceptors
  110. what are baroreceptors??
    sensory receptors that respond to changes in blood pressure
  111. there are 2 major types of baroreceptors, what are they?
    • aortic arch baroreceptors
    • carotid sinus baroreceptors
  112. where is the aortic arch baroreceptors, and what does it connect to?
    • located in the wall of the aortic arch
    • connect with the cardiovascular center via the Vagus (X) nerves
  113. where are the  carotid sinus baroreceptors, and what does it connect too?
    • located in the walls of the carotid sinuses
    • connect with the cardiovascular center via the glossopharyngeal (IX) nerves
  114. The carotid sinuses are dilated regions of.....
    the internal carotid arteries just above the area where these arteries branch off of the common carotid arteries
  115. The ↑ in blood pressure causes the baroreceptors to stretch more than normal. Consequently,
    the baroreceptors send a large number of action potentials to the cardiovascular center
  116. after the baroreceptors send a large number of action potentials to the cardiovascular center The cardiovascular center responds by activating what??
    the parasympathetic (Vagus) nerves that supply the heart, which causes the heart rate to ↓.
  117. after the parasympathetic (Vagus) nerves that supply the heart, which
    causes the heart rate to ↓.. so = A ↓ in heart rate causes a..
    ↓ in cardiac output
  118. A ↓ in cardiac output results in what??
    • a ↓ in blood pressure back to
    • normal
  119. The ↓ in blood pressure causes the baroreceptors to stretch less than normal. Consequently,
    the baroreceptors send fewer action potentials to the cardiovascular center.
  120. since  the baroreceptors send fewer action potentials to the cardiovascular center, The cardiovascular center responds by activating the cardiac accelerator nerves that supply the heart, which causes..
    an ↑ in stroke volume and heart rate, and therefore an ↑ in cardiac output. In addition, the cardiovascular center activates the vasomotor nerves that supply most of the blood vessels of the body, which causes vasoconstriction.
  121. The ↑ in cardiac output and the vasoconstriction cause a...
    ↑ in blood pressure back to normal
Author
Stefanizetina
ID
340641
Card Set
CH. 4 VASCULATURE
Description
CH. 4 Vasculature
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