Medic 14 A&P Chapter 13 notes

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Medic 14 A&P Chapter 13 notes
2013-04-03 12:37:55
Medic 14

Chapter 13 notes
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  1. Vocab
  2. Baro-
    pressure; baroreceptors
  3. capillaris
  4. manometer
    device of measuring pressure; sphygmomanometer
  5. porta
    gate; portal vein
  6. pulmo-
  7. pulsus
  8. saphenes
    prominent;saphenous vein
  9. skleros
  10. sphygmos
    pulse; sphygomanometer
  11. Vaso-
    vessel; vasoconstriction
  12. Objective:
    Distinguish among the types of blood vessels on the basis of their structure and function.(pp.467-472)
  13. Blood leaves the heart by the
    pulmonary trunk and aorta
  14. Aorta and pulmonary trunk branch repeatedly to form
    the major arteries
  15. Branching of the arteries form
  16. Arterioles supply blood to
  17. How small is are cappillaries?
    barely the diameter of a single red blood cell
  18. Vital function preformed at the cappillary level is
    Chemical and gaseous exchange between the blood and interstitial fluid
  19. Blood flows out of the cappilary network and enters
    the venules, the smallest vessels of the venous system
  20. Venules merge to from small
  21. Blood passes through medium and large veins before reaching the _____ _____ or _________ ____
    • venae cavae
    • pulmonary veins
  22. Three layers of arteries and veins
    • tunica interna
    • tunica media
    • tunica externa
  23. Tunica interna
    • tunica intima
    • innermost layer
    • enodthelial lining of the vessel and underlying layer of connective tissue dominated by elastic fibers
  24. Tunica Media
    • middle layer
    • contains smooth muscle tissue in a framework of collagen and elsatic fibers
    • when contracted diameter decreases
    • relaxed increases
  25. Tunica Externa
    • tunica adventitia
    • forms a sheath of connective  tissue around the vessel.
    • collegen fibers may intertwine with those of adjacent tissues, stabilizing and anchoring the blood vessel
  26. Arteries and veins often lie
    side by side in a narrow band of connective tissue
  27. greater wall thickness is a characteristic of
  28. arterial smooth muscle is under control of
    sympathetic division of the ANS
  29. Arterial constriction is the process of
  30. Relaxation increases diameter of the arterial lumen in a process called
  31. Types of Arteries
    • Elastic Artery
    • Muscular Artery
    • Arteriole
  32. Elastic Artery
    • large, Extremely resilient vessels
    • Examples are pulmonary trunk and aorta and major branches
    • Tunica media dominated by elastic fibers rather then smooth muscle cells
    • allows absorbtion of pressure changes during cardiac cycle
  33. How do elastic Arteries absorb pressure changes?
    • During ventricle systole, elastic arteries stretch and diameter increases 
    • During diastole, arterial blood pressure declines and elastic fibers recoil to original dimensions
  34. Muscular Arteries
    • Medium sized arteries or disribution arteries 
    • distribute to skeletal muscles and internal organs
    • thick tunica media contains more smooth muscle and twer elastic fibers contrasted to elastic artery
  35. Arterioles
    • much smaller then muscular arteries 
    • tunica media contains one to two layers of smooth muscle cells these layers allow change of diameter of the lumen
    • altering BP or and rate of flow through dependent tissues, characteristic found in muscular arteries as well
  36. Capillaries
    • Only blood vessel whose walls permit exchange between blood nad surround intersitial fluid 
    • Small diameter of capillaries allow sufficient time for diffusion or active transport of materials across the capillary walls
  37. Typical capillary considles of single layer of
    endothelial cells inside a basement membrane. Neither tunica externa or tunica media is present
  38. Network of capillaries are called
    capillary bed
  39. A single arterole gives rise to dozens of capillary beds which collect into
    several venules
  40. Entrance of each capillary is guarded by
    precapillary sphincter, a band of smooth muscle
  41. Contraction and relaxation of the precapillary sphincter
    • Contratcion narrows reducing blood flow
    • relaxation dilates and allowing blood to enter cappilary more rapid
  42. Vasomotion
    blood flow within a any one capillary is intermittent rather then a steady and consistant stream due to precapillary sphincters alternatle contracting and relaxing around a dozen times a minute
  43. Autoregulation at the tissue level
    • smooth muscle fibers respond to local changes in concentraions of chemicals and dissolved gasses in the interstital fluid
    • for example then dissolved oxygen levels decline in a tissue, cappillary sphincters relax and blood flows increases to the area.
  44. Anastomosis
    joining of two tubes
  45. arteriovenous
    blood bypasses capillary beds
  46. Anastomosis
    a vessel that connects an arteriole to a venule
  47. Arterial anastomosis
    a single capillary bed is supplued by this , more then one artery fuses before giving rise to arterioles
  48. Veins
    Collect blood from all tissues and organs and return it to the heart.
  49. Three types of veins
    • Venules 
    • Medium sized
    • Large size
  50. Venules
    • resemble expanded capillaries 
    • they lack a tunica media
  51. Medium sized
    • comparable to muscular arteries 
    • tunica media contains several smooth muscle layers and relatively thick tunica externa has longitudial bundles or elastic and collagen fibers
  52. large veins
    include the venae cava and their tibutaries in the abdonminopelvic and thoracic cavities. thin tunica media is sourrounded yb a think thinica externa composed if elastic and collagenous fibers
  53. Medium sized veins in extremities  contain
    valves which are folds of endothelium that function like the valves in the heart and prevent backflow of blood
  54. Objective: 
    Explain the mechanisms that regulate blood flow through arteries, capillaries, and veins.(pp.472-473)
  55. Flow of blood through the capillaries depends on what factors
    • Cardiac Output
    • pressure 
    • resistance
  56. Blood flow are pressure are directly related how?
    when pressure increases, flow increases.
  57. Blood flow and resistance are inversely related how?
    when resistance increases, flow decreses
  58. To keep blood moving the heart must generate enough pressure to overcome...
    the resistance to blood flow in the pulmonary and systemic circuits
  59. Force exerted against generates
    • hydrostatic pressue that is conducted in all directions
    • if pressure difference exists a liquid will flow from an area of higher pressure to an area of lower pressure
  60. Flow rate is proportional to pressure gradient 
    the greater the difference in pressure...
    the faster the flow
  61. Largest pressure gradient in the body is found where?
    • in the systemic circuit between the base of the aorta and the entrance of the right atrium
    • This pressure difference is called the circulatory pressure, averages about 100 mmHg
    • This is the force needed to force blood through the arterioles and capillaries
  62. Circulatory pressure is divided into three components
    • arterial pressure(blood pressure
    • capillary pressure
    • venous pressure
  63. Resistance is
    any force that opposes movement
  64. For blood to flow the circulatory pressure must do what vrs the total peripherial resistance
    Must be great enough to overcome the total peripherial resistance
  65. Total peripherial resistance  is the
    resistance of the entire cardiovascular system
  66. The resistance of the arterial system is termed
    peripheral resistance
  67. sourses of peripheral resistance include
    • vascular resistance
    • viscosity
    • turbulence
  68. Vascular resistance
    is the resistance of blood vessels  to the blood flow
  69. Most important factor in vascular resistance is
    friction between blood and the vessel walls
  70. The amount of friction depends on
    • length of the vessel and its diameter.
    • Friction inceases with increasing vessel length and with decreasing vessel diameter
  71. Most of the vascular resistance occurs in the arterioles
    which are extremely muscular
  72. local, neural, and hormonal stimuli can stimulate or inhibit
    the smooth muscle tissue and can adjust the diamaters of these vessels
  73. Viscosity
    is the resistance to the flow that results from interactions among molecules and suspend materials in a lquid
  74. Highly viscous liquids will only flow under
    higher pressures as opposed to liquids of a low viscosity
  75. Turbulence
    • is a fluid regime characterized by chaotic,stochastic property changes. Includes low momentium diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time
    • Flow that is not turbulent is called laminar flow
  76. Turbulant flow across damaged or misalinged heart valvus produces the sound of
    heart murmurs
  77. Of the three sources of resistance , only what is can be adjusted by the nervous system or endocrine system to regulate blood flow
    Vascular resistance
  78. Viscosity and turbulence, which affect peripheral resistance are
    normally constant
  79. Objective:
    Discuss the mechanisms and various pressures involved in movement of fluids between capillaries and intersitial spaces(pp.473-476)
  80. Systemic pressure is highest in the
    Aorta, peak around 120mmhg
  81. Systemic pressure is lowest at the
    Venae cavae,average about 2 mmHg
  82. Systolic pressure
    is the peak of blood pressure measured during ventriuclar systole
  83. Diastolic pressure
    is miniumim blood pressure at the end of ventricular diastole
  84. Pulse
    is the rthythmic pressure oscillation that accompanies each heartbeat
  85. Pulse pressure
    the differnece between the systolic and diastolic pressure
  86. Pulse pressure lessens  as the distance from the heart
  87. Major source of friction between blood and the vessel walls is due to
    the elasticity of the arteries
  88. Whn diastole begins and blood pressure fall the arteries recoil to their origional dimensions, this is  referred to as
    elastic rebound
  89. Capillary pressure
    pressure of blood within a capillary bed
  90. Four important functions of Capillary exchange:
    • Maintaining constant communication between plasma and intersitial fluid
    • speeding the distribution of hormones,nutrients, and dissolved gases throughout tissues
    • assisting the movement of insoluble lipids and tissue proteins that cannot cross capillaty walls
    • flusing bacterial toxins and other chemical stimuli to lymphoid tissues and organs that function in providing immunity to disease
  91. Movement of materials across capillary walls occurs by
    • diffusion
    • filtration
    • osmosis
  92. Solute molecules tend to diffuse across the capillary lining driven by
    their individual concentration gradient
  93. Water will move either by
    hyrdostatic pressure or osmotic pressure
  94. At the capillary hydrostatic pressure is referred to as
    Capillary hydrostatic pressure (CHP)
  95. CHP is greatest at
    the arteriolar end
  96. CHP is least at
    the venous end
  97. Osmosis is the movement of water across
    A selectively permaible membrane that separates two solutions with two soulte concentrations
  98. Osmotic pressure
    water moves into the soultiuon with the higher solute concentration and the force of that is referred as Osmotic pressure
  99. Blood contains more dissolved proteins then water, thus its osmotic pressure is higher and
    water tends to move from interstital fluid into the blood
  100. CHP tends to pust water out of the capillary and whereas BOP (blood osmotic pressure) forces
    tend to reabsorb or pull water back
  101. as blood travels through the veins the resistance drops
    • 18mmHg a in the venules, 2mmHg at the venae cavae
    • 16 mmHg through medium veins
  102. 16mmHg pressure gradient is sufficent while laying down when standing venous blood ,ust overcome
    gravity as it ascends within the interior vena cava
  103. Two factors that help overcome gravity and propel venous blod toward the heart
    • Muscular compression
    • Respiratory pump
  104. Muscular compression
    contratcions of skeletal muscle near a vein compress it and help push blood toward the heart
  105. Respiratory pump
    • as you inhale pressure in the thoratic cavity draws air into the lungs
    • that drop in pressure causes the inferior vena cavae and right atrium to expand and fill with blood, which increases venous return
    • during exhaltation increased pressure compresses venae cavae pushing blood into the right atrium
  106. Objective:Describe the factors that influence blood rpressure and the mechanisms that regulate pressure (pp.476-478)
  107. Tissue Perfusion
    Homeostatic mechanisms that regulate cardiovascular activity to ensure tissue blood flow to meet demand for oxygen and nutrients
  108. Factors that influence tissue blood flow are
    • cardiac output
    • peripherial resistance
    • blood pressure
  109. Most cells are relatively close to capillaries, when a group of cells become active circulation to that region
    muist increase to deliver the oxygen and nutrients they need and to carry away the waste prodycts and carbon dixoide they generate
  110. Goal of cardiovascular regulation is to ensure that blood flow chagnes occur
    • at the appropriate time
    • in the right area
    • without drasically altering blood pressure and without drastically altering blood flow to vital organs
  111. Mechanisms involved in regulation of cardiovascular function include
    • autoregulation
    • neural mechanisms 
    • endocrine mechanisms
  112. Autoregulation
    • changes in tissue cocditions act directly on precapillary sphincters to alter peripheral resistance, producing local changes in patten of blood flow within capillary beds
    • such autoregulation causes immediate localized homeostatic regulations called Homeostatic adjustments
  113. If autoregulation is unable to normalize tissue conditions,
    Neural and endocrine mechanisms are activated
  114. Neural Mechanisms
    • respond to changes in arterial pressure or blood gas levels in specific sites
    • when these changes occur the ANS adjusts cardiac output and peripheral resistance to maintain adequate blood flow
  115. Endocrine mechanisms
    Releases  hormones the enhance the short term adjusttments and direct long term changes in cardiovascular performance
  116. Short term responses
    adjust cardiac output and peripheral resistance to stabilize blood pressure and blood flow to tissues
  117. Long term adjustments
    involve alterations in blood volume that affect cardiac output and the transport of oxygen and carbon dioxide to and from active tissues
  118. Autoregulation
    • as Co2 levels rise and pH falls, these changes signal the smooth muscle cells in precapillary sphincters to relax and blood flow increases.
    • release of NO by capillary cells stimulated by high shear forces along the capillary walls or presence of histamine at an injury site during inflamation triggers relaxation of precapillary sphincters
  119. Factors that promote dilation of precapillary sphincters are called
  120. Those that stimulate constriction of precapillary sphincters are
  121. Nervous system adjusts cardiac output and peripheral resistance through
    the cardiac centers and vasomotor centers of the medulla oblongata
  122. Cardiovascular (CV) centers
    Cardiac/vasomotor centers of the medulla oblongata
  123. Each cardiac center includes
    • a cardioacceleeratory cemter
    • cardioinhibitory center
  124. Cardioacceleratory center
    Increases cardiac output through sympathetic innervation
  125. cardioainhibitory center
    reduces cardiac output through parasympathetic innervaition
  126. Vasomotor centers
    • primarily control the diameters of the arterioles through sympathetic innervation
    • Inhibiton of the vasomotor center leads to vasodilation
  127. Cardiovascular centers detect changes in tissue demand by montoring
    arterial blood, for BP, pH , and dissolved gas concentrations
  128. Baroreceptor reflexes respond to changes in
  129. Chemoreceptors
    respond to changes in chemical composition
  130. Those reflexes are regulated through
    negative feedback
  131. Baroreceptors
    monitor the degree of stretch in the walls of expandable organs
  132. baroreceptors are located
    • aortic sinuses (pockets in the wall of the aorta adjacent to the heart)
    • Carotid sinuses(in the walls of, which are expanded chambers near the bases of the internal carotid arteries of the neck)
    • In the wall of the right atrium
  133. Baroreceptor reflexes
    autonomic reflexes that adjust cardiac output and peripheral resistance to maintain normal arterial pressures
  134. Aortic baroreceptors
    monitor  blood presure within the ascening aorta
  135. Aortic reflex
    • adjusts BP in response to changes in pressure
    • maintain adequate BP and blood blow through the systemic circuit
  136. Carotid sinus baroreceptors
    • respond to changes in bp at the carotid sinuses
    • Trigger reflexes that mainatain adequate blood flow to the brain
  137. Carotid sinus reflex is
    extremely sensitive
  138. When BP, rises due to output of baroreceptors, where it inhibits the cardioacceleratoru center, stimulates the cardioinhibitory center and inhibits vasomotor centers
    two effects are produced
    • Under command of the cardioinhibitory center , the vagus nerves release ACh, which reduces rate and strength of cardiac contracions,decreading cadiac output
    • inhibition of the vaomotor center leads to dilation of peripheral aterioles throughout the body
  139. Cardioaccelatory center stimulates
    • sympathetic neurons that innervate the SA node and AV node nad general myocardium
    • this stimulation leads to increased heart rate and stroke volume
    • immediate cardiac output increase
  140. Vasomotor activity  also carried by sympathetic motor neurons produces
    rapid vasoconstriction
  141. Atrial Baroreceptors
    monitor bp at the end of the systemic circuit at the venae cavae and right atrium
  142. Atrial reflex responds to
    stretching of the wall of the right atrium
  143. A rise in Bp at the atrium means  that
    blood is arriving at the heart faster then it is being pumped out
  144. Atrial baroreceptors correct the situation by
    stimulating cardioacceleratory enter, inceasing cardiac output untill the backlog of venous blood is removed, the atrial pressure retunrs ot normal
  145. Chemoreceptor reflexes
    respond to changes in Co2 oxygen, and pH in  blood/CSF
  146. Chemoreceptors involved are sensory neurons found in the
    • carotid bodies
    • aortic bodies 
    • on the medulla oblongata
  147. Cheemoreceptors are activated by a
    • drop in pH, or in plasma O2 or by a rise in CO2
    • these changes lead to stimulation of cardioacceleratoy and vasomotor centers
  148. Chemoreceptor output also affect
    the respiratory centers in the medualla oblongata
  149. Rise in blood flow and BP is assocated with an elevated respiratory rate
    this coordination of cardiovasuclar and respiratory activity is vital, due to oxygen demands and rise in respiratory rate accelerates venous return through the respiratory pump
  150. Endocrine system provides both
    short term and long term regulation of the cardiovascular system
  151. Short term
    N, NE from adrenal medullae stimulate cardiac output and peripheral vasoconstricion
  152. Long term
    • involves participation  of hormonessuch as
    • ADH
    • Angiotension II
    • EPO
    • ANP
    • hormones help in regulation of BP and blood volume
  153. ADH (antidiuretic Hormone)
    • ADH is realeased at the posterior of the piuitary gland in response to a decrease in blood volume, increase in osotic concentraion of the plasma, or in repsonse to presence of angiotension II
    • Immediate result is peripheral vasoconstriction that elevates blood pressure.
    • ADH  has water conveserving effect on the kidneys, prevents a reduction in blood volume
  154. Angiotension II
    • formed by the release of the enzyme renin by specialized kidney cells in response to a fall in blood pressure.
    • renin starts chain reaciton that converts inacitve plasma protein,angiotension to hormone angiotension II.
    • angiotension II stimulates cardiac output and triggers arteriole constiction, which in tirn elevates systemic blood pressure
    • Stimulates release of ADH and aldosterone by the adrenal cortex
  155. Aldosterone
    stimulates the reabsorption of sodium ions and water from urine
  156. EPO(Erythopoietin)
    • is released by the kidneys when blood pressure falls or the oxygen content of the blood becomes abnormally low
    • EPO stimulates RBC production
  157. ANP (atrial natriuretic Peptide)
    • ANP release is stimulated by increased blood pressure 
    • ANP is produced by specialized cardiac muscle cells in the arial walls when they are streched by excessive venous return.
  158. ANP reduces blood volume and BP by
    • increasing the loss of sodium ions at the kidneys
    • promoting water losses by increasing the volume of urine produced
    • reducing thirst
    • blocking the relase of ADH,aldosetrone, E,NE, stimulating peripheral vasodiaton
    • as blood volume and blood pressure decline , tension on the atrial wealls is removed and ANP production ceases
  159. Objective:
    explain how the activites of the cardiovascular system responds to the demands of exercise and hemmorage (pp.482-483)
  160. When exercise beings several changes take place
    • Extensive vasodilation
    • venous return increases 
    • cardiac output rises