BIOL 121 Chp 21: The Cardiovascular System - Blood Vessels and Hemodynamics

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This is a lecture presentation for my BIOL 121 Anatomy and Physiology I students on Chapter 21: The Cardiovascular System: Blood Vessels and Hemodynamics (Principles of Anatomy and Physiology, 14th Ed. by Tortora and Derrickson).

Rob Swatski, Associate Professor of Biology, Harrisburg Area Community College - York Campus, York, PA. Email: rjswatsk@hacc.edu

Please visit my website for more anatomy and biology learning resources: http://robswatski.virb.com/

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BIOL 121 Chp 21: The Cardiovascular System - Blood Vessels and Hemodynamics

  1. 1. 1   Rob  Swatski   Associate  Professor  of  Biology   HACC  –  York  Campus   Chapter  21     The  Cardiovascular   System:       Blood  Vessels  &   Hemodynamics   Textbook images - Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
  2. 2. 2   Blood  Vessels   Structure  &   FuncHon   Arteries  &   Arterioles   Veins  &   Venules   Capillaries   Hemodynamics   Circula4on   Regula4on  
  3. 3. Types  of  Blood  Vessels   Arteries:   transport  blood   away  from   heart   Arterioles:   transport  blood   to  capillaries     Capillaries:   gas  &  solute   exchange   3  
  4. 4. Types  of  Blood  Vessels   Venules:   drain  blood   from  capillaries   into  larger  veins   Veins:   return  blood   to  the  heart   Vaso   Vasorum:   transport  blood   to  4ssues  of  BV   wall   4  
  5. 5. 5   Anastomosis   End  artery  
  6. 6. 6   Layers  of   the  Artery   Wall   Tunica   externa   Tunica   media   Tunica   interna  
  7. 7. 7   Layers  of  the  Artery  Wall   Tunica  externa   Elas4c  &   collagen   fibers   Tunica   media   Circular   smooth   muscle   External   elasHc   lamina   Tunica  interna   Internal   elasHc   lamina  &   basement   membrane   Endothelium   (simple   squamous   epithelium)  
  8. 8. 8  
  9. 9. 9   Transverse  SecHon  Through  an  Artery  
  10. 10. 10   FuncHonal   ProperHes   of  Arteries   ElasHcity   (elas4c  lamina)   ContracHlity   (smooth   muscle)  
  11. 11. 11   SympatheHc   Nervous   System   RegulaHon   VasoconstricHo n  (Vasospasm)   VasodilaHon   (NO,  K+,  H+)  
  12. 12. 12   ElasHc   Arteries   =  ConducHng   arteries   Largest  diameter  &   thicker  elas4c   lamina  (elas4c   lamellae)   Less  smooth   muscle   Pressure   reservoir  
  13. 13. 13  
  14. 14. 14   Muscular   Arteries   =  DistribuHng   arteries   Medium  diameter   &  thinner  elas4c   lamina   More  smooth   muscle  &  thicker   walls   Stronger   vasoconstric4on  
  15. 15. 15   Arterioles   Very  small   diameter  &  less   smooth  muscle   Deliver  blood  to   capillaries   Regulate  blood   flow   Adjust  arterial   blood  pressure  
  16. 16. 16   Metarterioles   Regulate  blood   flow  into   capillaries   Precapillary   sphincters   Thoroughfare   channel   VasomoHon:  fills   bed  5-­‐10x/min  
  17. 17. 17   Blood  Flow   Into   Capillary   Bed  
  18. 18. 18   Blood  Flow   Into   Thoroughfare   Channel  
  19. 19. 19   Capillaries   Connect  arterioles   to  venules   Capillary  bed   MicrocirculaHon   Gas,  nutrient,  &   waste  exchange  
  20. 20. 20  
  21. 21. 21  
  22. 22. 22   ConHnuous   Capillaries   Endothelium  with   “leaky”  4ght   junc4ons   Intercellular  cleQs   In  skeletal  &   smooth  muscle,   lungs,  connec4ve   4ssue  
  23. 23. 23  
  24. 24. 24   Fenestrated   Capillaries   Endothelium  with   many  fenestraHons   (pores)   Intercellular  cleds   In  kidneys,  small   intes4ne,  glands,   choroid  plexuses  
  25. 25. 25  
  26. 26. 26   Glomerulus  
  27. 27. 27  
  28. 28. 28   Sinusoids   Endothelium  with   incomplete   basement   membrane   Very  large   fenestra4ons  &   intercellular  cleds   In  liver,  bone   marrow,  spleen,   pituitary  gland  
  29. 29. 29  
  30. 30. 30   Venules   Drain  capillary  beds   Thin  walls  &  less   smooth  muscle     Blood  reservoir   Postcapillary  venules:   very  porous   endothelium   Microcircula4on,   emigra4on  of  WBCs   Lead  to  muscular   venules  
  31. 31. 31   Veins   Have  same  3  layers   as  arteries   Thinner  walls  with   valves   Lifle  smooth   muscle  &  no  elas4c   lamina     Thicker  tunica   externa   Adapt  to  changes  in   volume  &  pressure  
  32. 32. 32   Venous   (Vascular)   Sinuses   Very  thin  walls   No  smooth  muscle   Surrounded  by  dense   CT  for  support   Superior  sagifal   sinus,  coronary  sinus  
  33. 33. 33   Other   Differences   Between  Veins   and  Arteries   Veins  are  more   abundant   Veins  can  be  found  in   double  sets  called   anastomoHc  veins   Many  superficial   veins  in  SubQ  layer   Deep  veins  
  34. 34. 34   Varicose   Veins   Dilated,  twisted   superficial  veins   caused  by  leaky   valves   Congenital  or   due  to  physical   stress   Blood  pools-­‐up   in  veins   Higher  pressure   forces  fluids  into   ECF  
  35. 35. 35   Varicose   Veins   In  legs,   esophagus,  anal   canal   (hemorrhoids)   Why  is  it   uncommon  for   deeper  veins  to   become   varicose?  
  36. 36. 36   Anastomoses   2  or  more  BVs   supplying  same   region   Angiogenesis   Collateral   circulaHon   (alternate  routes)   Ex:  circle  of  Willis,   coronary   circulaHon  
  37. 37. 37  
  38. 38. 38   Blood  DistribuHon  
  39. 39. 39   Capillary   Exchange   Transfer  of   chemicals  b/w   blood  &  inters44al   fluid   Through  diffusion,   transcytosis,  and   bulk  flow   Across   endothelium,   through  cleds  &   fenestra4ons   O2,  CO2,  glu,  AA,   hormones,  solutes  
  40. 40. 40   Blood-­‐Brain   Barrier   (BBB)   No  diffusion  of   water-­‐soluble   solutes   Con4nuous   capillaries  with   4ght  junc4ons   No  cleds  or   fenestra4ons  
  41. 41. 41   Transcytosis   Moves   substances   through   endothelium   Uses  vesicular   transport   (endocytosis  &   exocytosis)   Transports   larger,  lipid-­‐ insoluble   molecules   (proteins)  
  42. 42. 42   Bulk  Flow   Moves  large   amounts  of   substances  in   same  direc4on   Faster  transport   rates  (high  to   low  pressure)   Regulates  blood   &  inters44al   fluid  volumes   FiltraHon  &   ReabsorpHon  
  43. 43. 43  
  44. 44. 44   FiltraHon   Moves  substances   out  of  blood  and   into  inters88al   fluid   Blood   HydrostaHc   Pressure   (BHP)   IntersHHal   Fluid  OsmoHc   Pressure   (IFOP)  
  45. 45. 45   ReabsorpHon   Moves   substances  from   inters44al  fluid   into  capillaries     Blood  Colloid   OsmoHc   Pressure   (BCOP)   IntersHHal   Fluid   HydrostaHc   Pressure   (IFHP)  
  46. 46. Net filtration pressure (NFP) Blood plasma Blood flow from arteriole into capillary Lymphatic fluid (lymph) returns to Lymphatic capillary Key: BHP = Blood hydrostatic pressure IFHP = Interstitial fluid hydrostatic pressure BCOP = Blood colloid osmotic pressure IFOP = Interstitial fluid osmotic pressure NFP = Net filtration pressure Blood flow from capillary into venule BHP = 16 mmHg BCOP = 26 mmHg IFHP = 0 mmHg Interstitial fluid IFOP = 1 mmHg BCOP = 26 mmHg BHP = 35 mmHg Tissue cell N F P Net filtration at arterial end of capillaries (20 liters per day) (BHP + IFOP) Pressures promoting filtration Net reabsorption at venous end of capillaries (17 liters per day) (BCOP + IFHP) Pressures promoting reabsorption Arterial end Venous end NFP = (35 + 1) – (26 + 0) = 10 mmHg NFP = (16 + 1) – (26 + 0) = –9 mmHg Net filtration Net reabsorption N F P = – Result
  47. 47. 47   Net  FiltraHon   Pressure   (NFP)   Net  outward   pressure  =     10  mmHg  at   arterial  end   Net  inward   pressure  =     9  mm  Hg  at   venous  end   85%  of  filtered   fluid  returns  to   capillaries  via   lympha4cs  (3L/ day)  
  48. 48. Volume   Reabsorbed   Volume   Filtered   48   Starling’s  Law  of  the  Capillaries  
  49. 49. Edema   Due  to  excess   filtraHon   High  blood   pressure   (hypertension)   High  capillary   permeability   (leaks  plasma   proteins)   Due  to  poor   reabsorpHon   Low  plasma   proteins  (lowers   BCOP)   Slow  protein   synthesis  or  loss   due  to  liver  or   renal  problems   49  
  50. 50. 50  
  51. 51. 51  
  52. 52. 52   Blood   Pressure  (BP)   Cardiac   Output  (CO)   Volume   Viscosity   Velocity   Resistance   ElasHcity   Venous   Return   Factors  AffecHng  Hemodynamics  
  53. 53. 53  
  54. 54. 54   Resistance   Opposi4on  to   blood  flow  due  to   fric8on   Highest  in   arterioles,   capillaries,  &   venules   Vascular   resistance:  varies   with  diameter,   viscosity,  length   Systemic   Resistance:  total  
  55. 55. 55   Blood   Pressure  (BP)   Due  to  ventricular   systole  (120  mmHg  in   aorta)   BP  increases  as  CO   increases   BP  decreases  away   from  led  ventricle   35  mmHg  @   capillaries   0  mmHg  @  right   atrium  
  56. 56. 56  
  57. 57. 57   Venous   Return   Volume  of  blood   flow  returning  to   heart  from  veins   Skeletal  muscle   pump:  muscle   contrac4on  &   valves   Respiratory  pump:   moves  blood  into   right  atrium   Lower  thoracic   pressure  à  Higher   abdominal   pressure  during   inhala4on  
  58. 58. 58  
  59. 59. 59   Velocity  of   Blood  Flow   Inversely  related  to   BV  cross-­‐sec4onal   area   Flow  is  slowest   where  cross-­‐ sec4onal  area  is   highest   Velocity  decreases   from:  aorta  à   arteries  à   capillaries   Velocity  increases   from:  veins  à   right  atrium   3-­‐5  cm2   40  cm/sec   4500-­‐6000  cm2   0.1  cm/sec   14  cm2   15  cm/sec
  60. 60. 60   Factors  that  Increase  Blood  Pressure  
  61. 61. 61   Control  of  BP   and  Blood   Flow   Cardiovascular   Center:  in  medulla   oblongata  of   brainstem   Sympathe4c  &   parasympathe4c   control   Regulates  HR,   contrac4lity,  &  BV   diameter   Vasomotor  nerves:   adjust  BV  diameter   vasodilator  center  
  62. 62. 62   vasomotor  tone  
  63. 63. 63   Neural   RegulaHon   of  BP   Baroreceptors:  in   major  arteries   CaroHd  sinus   reflex:  maintains   brain  BP   AorHc  reflex:   maintains  general   systemic  BP   If  BP  decreases:   HR,  contrac4lity,   &  vasoconstric4on   increase      
  64. 64. 64  
  65. 65. 65  
  66. 66. 66  
  67. 67. 67   Syncope   (FainHng)  
  68. 68. 68   Syncope   A  sudden  loss  of  consciousness  due  to  cerebral  ischemia  (fainHng)   Vasodepressor   syncope   Sudden  emo4onal   distress   SituaHonal   syncope   Pressure  stress  of   coughing,   defeca4on,   urina4on     Drug-­‐induced   syncope   Diure4cs,  an4-­‐ hypertensives,   vasodilators,   tranquilizers   OrthostaHc   hypotension   BP  decrease  upon   standing  
  69. 69. 69  
  70. 70. 70  
  71. 71. 71   Chemoreceptor   Reflexes   CaroHd  bodies  &   AorHc  bodies   Detect  changes  in   blood  O2,  CO2,  H+     Hypoxia,   hypercapnia,  acidosis   S4mulate  CV  center:   increases   vasoconstric4on  &   respiratory  rate  
  72. 72. 72   Hormonal   RegulaHon  of   BP   Renin-­‐ Angiotensin-­‐ Aldosterone   system  (RAA)     Ac4vated  by   drop  in  BP  or   reduced  blood   flow  to  kidney   Kidneys  à  Renin  
  73. 73. 73   Renin   Angiotensin     (vasoconstricHon)   Aldosterone     (H2O  &  salt   reabsorpHon)  
  74. 74. 74   Hormonal  RegulaHon  of  BP,   cont.   Epinephrine  &   Norepinephrine   Increases  HR  &   contrac4lity  à   raises  BP   ADH   (AnHdiureHc   Hormone)  [aka   vasopressin]   Triggers   vasoconstric4on   à  raises  BP   Promotes  reabsorp4on  of   H2O  into  blood  à   increases  blood  volume  &   decreases  urine  output   ANP  (Atrial   NatriureHc   PepHde)   Triggers   vasodila4on   à  lowers  BP   Increases  loss  of   Na+  and  H2O  in   urine  à  lowers   blood  volume  
  75. 75. 75   Pulse   Alterna4ng   expansion  &  recoil   of  elas4c  arteries   ader  every  le<   ventricle  systole   ResHng  pulse  rate:   avg  70-­‐80  bpm   Tachycardia:  >100   bpm   Bradycardia:  <50   bpm  
  76. 76. 76  
  77. 77. 77   Measurement   of  BP   Sphygmomanometer   (BP  cuff)   Korotkoff  sounds:   provide  info  about   systemic  resistance     Systolic  BP:   ventricular   contrac4on  (120   mmHg)   Diastolic  BP:   ventricular  relaxa4on   (80  mmHg)   Pulse  pressure:   difference  b/w   systolic  &  diastolic   BP  (=  40  mmHg)  
  78. 78. 78  
  79. 79. 79   Shock   Poor  CO:  cannot   deliver  enough  O2   &  nutrients   Cell  membrane   dysfunc4on  &   abnormal   metabolism   Cell  death  due  to:   poor  perfusion,   switch  to   anaerobic   respira4on,  &   lac4c  acid  build-­‐up  
  80. 80. 80   Weak,  but  rapid,  res4ng   pulse  (tachycardia)   Clammy,  cool,  pale  skin   (vasoconstric8on)   Altered  mental  state   (cerebral  ischemia)   Hypotension   Low  cardiac  output  (CO)   Swea4ng  (sympathe8c   s8mula8on)   Thirst  (loss  of  ECF)   Acidosis  (lac8c  acid   build-­‐up)   Decreased  urine   forma4on   (vasoconstric8on,   increased  aldosterone  &   ADH)   Signs  &  Symptoms  of  Shock  
  81. 81. 81   Types  of  Shock   Hypovolemic   Decreased  blood  or   body  fluid  volume   Hemorrhage,  poor  fluid   intake,  excessive   swea4ng,  vomi4ng,   diarrhea   Cardiogenic   Poor  heart  func4on   MI,  ischemia,  valve   disorders,  high  preload/ aderload,  arrhythmias,   poor  contrac4lity   ObstrucHve   Blockage  of  blood  flow   Pulmonary  embolism   Vascular   Inappropriate   vasodila4on   Anaphylac4c,  sep4c,  or   neurogenic  shock    
  82. 82. Hypovolemic shock CONTROLLED CONDITION Blood volume and blood pressure RECEPTORS CONTROL CENTER CONTROL CENTER CONTROL CENTER Liver and lungs Hypothalamus and posterior pituitary Cardiovascular center in medulla oblongata EFFECTORS Adrenal cortex Kidneys Blood vessels Heart Increased blood volume Increased systemic vascular resistance Increased blood pressure Return to homeostasis when responses bring blood volume and blood pressure back to normal Increased sympathetic stimulation and hormones from adrenal medulla ADH in bloodAngiotensin II in blood Increased secretion of renin Decreased rate of nerve impulses Inputs Outputs Disrupts homeostasis by moderately decreasing Baroreceptors in kidneys (juxtaglomerula r cells) Baroreceptors in arch of aorta and carotid sinus ADH EFFECTOR RESPONSE RESPONSE RESPONSE Kidneys conserve salt and water Blood vessels constrict Heart rate and contractility increase
  83. 83. 83   Decreased  elas4city  of   aorta   Smaller  size  of  cardiac   muscle  fibers   Decreased  CO,  but   maximum  HR   Increased  systolic  BP   Increased  total   cholesterol  &  LDL;   decreased  HDL   Increased  risk  of   conges4ve  heart   failure,  coronary  artery   disease,   atherosclerosis   Aging  &  the  Cardiovascular  System  
  84. 84. 84   Hypertension   Chronically  high  BP   (systolic  >  140  mmHg;   diastolic  >  90  mmHg)   Primary  hypertension:   most  common  (no   iden4fiable  underlying   cause)   Secondary   hypertension  (has   iden4fiable  cause)   Damages  BVs,  heart,   brain,  &  kidneys  before   onset  of  no4ceable   symptoms  
  85. 85. 85   Lose  weight   Reduce  alcohol   Increase  exercise   Reduce  salt   Eat  healthy  diet  to   maintain  K+,  Ca+2,   and  Mg+2   Don’t  smoke   Manage  stress   Meds:  diure4cs,   beta-­‐blockers,   vasodilators,  Ca+2   channel  blockers     Treatment  of  Hypertension  
  86. 86. 86  

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