The Cardiovascular System:Blood Vessels and Circulation          Chapter 16
Blood Vessels       Arteries        Carries blood away from the heart to         body tissues        2 large arteries ...
Blood Vessels       Veins        Convey blood from the tissues back to         the heart        Veins  smaller and sma...
Blood Vessels       Capillaries        Microscopic vessels that connect         arterioles to venules        “Exchange ...
Blood Vessel Structure Arteries   Three layers    Inner layer: endothelium, a basement     membrane, internal elastic l...
Blood Vessel Structure Veins   Similar structure to arteries   Thinner middle and inner layers, outer    layer is the t...
Capillary Information• Capillaries – layer of endothelium  surrounded by basement membrane• Connected from arterioles  ve...
Vessel Functions Muscular arteries & arterioles  regulate flow Sympathetic activity to smooth  muscle  vasoconstriction...
Vessel Functions Arterioles adjust flow into capillaries Systemic veins & venules serve as blood reservoirs (~64% total ...
Capillary Exchange Slow flow through capillaries Capillary Exchange – movement of  substances into and out of capillarie...
Capillary Exchange• Osmosis (protein concentration)  – Reabsorption of fluid from outside to inside• Balance determines fl...
Venous Return Volume of blood flowing back to the  heart through the systemic veins Happens due to pressure generated  i...
Venous Return Contractions of the heart –  BP generated by ventricular systole  Measured in mm of Hg (mercury)  Small ...
Venous Return Skeletal muscle pump –  Standing at rest – venous valves in leg   are open, blood flows up to heart  Cont...
Venous Return Skeletal muscle pump cont.   Same time as milking, valve farther from    heart closes as some blood is pus...
Venous Return Respiratory pump –  During inhalation   Diaphragm moves down, causes a drop in    pressure in the thoraci...
Blood Flow• From high pressure  low pressure – Greater gradient = greater flow • BP – pressure exerted by blood on  the w...
Blood Pressure BP is highest in aorta and large  systemic arteries BP depends on total volume of blood  Normal volume o...
Blood Pressure BP rises to ~110 mmHg (systole)  and drops to ~70 mmHg (diastole) BP drops as blood enters veins  and rea...
Blood Flow• Resistance – opposition to blood  flow due to friction between blood  and walls of vessels• Increase in resist...
Resistance• Size of lumen – Smaller lumen  greater resistance• Blood viscosity – Higher viscosity  greater resistance• T...
Regulation of Blood       Pressure & Flow CV Center (in the medulla oblongata)  Regulate heart rate & stroke volume  Co...
Inputs (CV center) Higher centers:  Cerebral cortex  Limbic system  Hypothalamus
Inputs (CV center) Sensory receptor input:  Proprioceptors    Monitor movements of joints and     muscles    Start HR ...
Inputs (CV center) Baroreceptors (cont.)   ↓ pressure  ↓ parasympathetic stimulation    of the heart  ↑ sympathetic st...
Output (CV center) ANS to heart  ↑ Sympathetic  ↑ HR & ↑ force of   contraction  ↓ Sympathetic  ↓ HR & ↓ force of   c...
Hormone Regulation Renin – Angiotensin – Aldosterone (RAA) system  Angiotensin II  ↑ BP (vasocontriction)  ↑ aldostero...
Hormone Regulation ADH = Vasopressin  ↑ Constriction  ↑ BP ANP  Vasodilation & loss of salt & water in  urine  ↓BP a...
Pulse Pulse strongest in arteries closest to heart  Radial artery (at wrist), Carotid artery,  Popliteal artery, Dorsal ...
Blood Pressure (measurement) Use sphygmomanometer  Usually on brachial artery in left arm Raise pressure above systolic...
Blood Pressure (measurement) Lower pressure in cuff until flow just starts  Systolic Pressure Lower until sound suddenl...
Circulatory Routes Two parts: Systemic & Pulmonary Systemic circulation- throughout body  Oxygenated blood  deoxygenat...
Systemic Circulation All systemic veins empty into Superior Vena Cava, Inferior Vena Cava or the Coronary Sinus  Carry d...
Pulmonary Circulation Right ventricle  pulmonary trunk R & L pulmonary arteries  Carry deoxygenated blood  R & L lu...
Pulmonary Circulation  R & L pulmonary veins  Carry oxygenated blood  L atrium
Hepatic Portal Circulation Portal vein transports blood from  one capillary bed to another There are no valves  Spleni...
Fetal Circulation Specialized for exchange of materials  with maternal blood and bypass of  lungs (placenta) Umbilical a...
Fetal Circulation Umbilical vein brings O2 blood from placenta  liver and Ductus Venosus  Inferior Vena Cava  R Atrium
Fetal Circulation Foramen ovale - hole in atrial septum allows mixing of blood in heart (eventually becomes fossa ovalis)
At Birth Umbilical arteries  medial umbilical  ligaments Umbilical vein  ligamentum teres Ductus venosus  ligamentum...
At Birth Placenta is “afterbirth” Foramen ovalis closes  fossa ovale Ductus arteriosus  ligamentum arteriosum
Aging Stiffening of aorta Loss of cardiac muscle strength  Reduced CO & increased systolic  pressure Coronary artery d...
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
Blood vessels
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Blood vessels

  1. 1. The Cardiovascular System:Blood Vessels and Circulation Chapter 16
  2. 2. Blood Vessels Arteries  Carries blood away from the heart to body tissues  2 large arteries  aorta and pulmonary trunk  Arteries smaller and smaller arteries arterioles  Arterioles  capillaries
  3. 3. Blood Vessels Veins  Convey blood from the tissues back to the heart  Veins  smaller and smaller veins  venules  Venules  capillaries
  4. 4. Blood Vessels Capillaries  Microscopic vessels that connect arterioles to venules  “Exchange Vessels”  permit exchange of nutrients and wastes between body’s cells and blood
  5. 5. Blood Vessel Structure Arteries  Three layers  Inner layer: endothelium, a basement membrane, internal elastic lamina  Middle layer: smooth muscle and elastic tissue  Outer layer: elastic and collagen fibers
  6. 6. Blood Vessel Structure Veins  Similar structure to arteries  Thinner middle and inner layers, outer layer is the thickest  The lumen is wider than artery  Some veins, inner layer folds inward  valves to prevent backflow
  7. 7. Capillary Information• Capillaries – layer of endothelium surrounded by basement membrane• Connected from arterioles  venules in networks – Sometimes direct route from arteriole to venule• Filling controlled by small arterioles & pre-capillary sphincters
  8. 8. Vessel Functions Muscular arteries & arterioles regulate flow Sympathetic activity to smooth muscle  vasoconstriction (narrowing) Decreased sympathetic activity or NO causes relaxation or dilation
  9. 9. Vessel Functions Arterioles adjust flow into capillaries Systemic veins & venules serve as blood reservoirs (~64% total blood volume)
  10. 10. Capillary Exchange Slow flow through capillaries Capillary Exchange – movement of substances into and out of capillaries Capillary Blood Pressure – pressure of blood against the walls of capillaries
  11. 11. Capillary Exchange• Osmosis (protein concentration) – Reabsorption of fluid from outside to inside• Balance determines fluid in circulation – Excess fluid returned via lymphatic system – Local signals can adjust capillary flow
  12. 12. Venous Return Volume of blood flowing back to the heart through the systemic veins Happens due to pressure generated in 3 ways:  Contractions of the heart  The skeletal muscle pump  Respiratory pump
  13. 13. Venous Return Contractions of the heart –  BP generated by ventricular systole  Measured in mm of Hg (mercury)  Small pressure difference between venules and right atrium is sufficient
  14. 14. Venous Return Skeletal muscle pump –  Standing at rest – venous valves in leg are open, blood flows up to heart  Contraction of leg muscles compresses vein  pushes blood through valve closer to heart, called milking
  15. 15. Venous Return Skeletal muscle pump cont.  Same time as milking, valve farther from heart closes as some blood is pushed against it  After muscle relaxation, pressure drops in compression and open valve closes, and now farther valve opens since BP is higher in foot than leg, vein fills with blood from foot
  16. 16. Venous Return Respiratory pump –  During inhalation  Diaphragm moves down, causes a drop in pressure in the thoracic cavity and rise in abdominal(ab) cavity  Ab veins compressed, greater volume of blood from compressed ab veins  decompressed thoracic veins  rt atrium  During exhalation, pressures reverse
  17. 17. Blood Flow• From high pressure  low pressure – Greater gradient = greater flow • BP – pressure exerted by blood on the walls of a blood vessel
  18. 18. Blood Pressure BP is highest in aorta and large systemic arteries BP depends on total volume of blood Normal volume of an adult ~5 L
  19. 19. Blood Pressure BP rises to ~110 mmHg (systole) and drops to ~70 mmHg (diastole) BP drops as blood enters veins and reaches 0 mmHg as blood returns  right atrium
  20. 20. Blood Flow• Resistance – opposition to blood flow due to friction between blood and walls of vessels• Increase in resistance = increase in BP• Decrease in resistance = decrease in BP• Resistance depends on 3 things
  21. 21. Resistance• Size of lumen – Smaller lumen  greater resistance• Blood viscosity – Higher viscosity  greater resistance• Total vessel length – Longer length  greater resistance
  22. 22. Regulation of Blood Pressure & Flow CV Center (in the medulla oblongata)  Regulate heart rate & stroke volume  Controls neural & hormonal negative feedback systems that regulate BP and flow to tissues
  23. 23. Inputs (CV center) Higher centers:  Cerebral cortex  Limbic system  Hypothalamus
  24. 24. Inputs (CV center) Sensory receptor input:  Proprioceptors  Monitor movements of joints and muscles  Start HR change as activity starts  Baroreceptors  Monitor pressure changes
  25. 25. Inputs (CV center) Baroreceptors (cont.)  ↓ pressure  ↓ parasympathetic stimulation of the heart  ↑ sympathetic stimulation Chemoreceptors  Monitor chemical changes  Low O2, high H+, excess CO2  ↑ sympathetic stimulation vasoconstriction  ↑ BP
  26. 26. Output (CV center) ANS to heart  ↑ Sympathetic  ↑ HR & ↑ force of contraction  ↓ Sympathetic  ↓ HR & ↓ force of contraction Vasomotor  to arterioles  ↑ vasomotor tone (sets resting level of vascular resistance)  To veins  move blood  ↑ BP
  27. 27. Hormone Regulation Renin – Angiotensin – Aldosterone (RAA) system  Angiotensin II  ↑ BP (vasocontriction) ↑ aldosterone  ↑ Na+ & water by kidneys Epinephrine and Norepinephrine  ↑ CO (↑ HR & force of contraction)
  28. 28. Hormone Regulation ADH = Vasopressin  ↑ Constriction  ↑ BP ANP  Vasodilation & loss of salt & water in urine  ↓BP and ↓ blood volume
  29. 29. Pulse Pulse strongest in arteries closest to heart  Radial artery (at wrist), Carotid artery, Popliteal artery, Dorsal artery, Brachial artery Tachycardia = rapid rest rate (>100 bpm) Bradycardia= slow rest rate (<50 bpm)
  30. 30. Blood Pressure (measurement) Use sphygmomanometer  Usually on brachial artery in left arm Raise pressure above systolic-  To stop blood flow
  31. 31. Blood Pressure (measurement) Lower pressure in cuff until flow just starts  Systolic Pressure Lower until sound suddenly gets faint (stops)  Diastolic pressure Normal values <120 mmHg for systolic & < 80 mmHg for diastolic  Ex. 115/75
  32. 32. Circulatory Routes Two parts: Systemic & Pulmonary Systemic circulation- throughout body  Oxygenated blood  deoxygenated All systemic arteries branch from aorta
  33. 33. Systemic Circulation All systemic veins empty into Superior Vena Cava, Inferior Vena Cava or the Coronary Sinus  Carry deoxygenated blood to heart
  34. 34. Pulmonary Circulation Right ventricle  pulmonary trunk R & L pulmonary arteries  Carry deoxygenated blood  R & L lungs  Gas exchange occurs
  35. 35. Pulmonary Circulation  R & L pulmonary veins  Carry oxygenated blood  L atrium
  36. 36. Hepatic Portal Circulation Portal vein transports blood from one capillary bed to another There are no valves  Splenic & superior mesenteric veins
  37. 37. Fetal Circulation Specialized for exchange of materials with maternal blood and bypass of lungs (placenta) Umbilical artery: pathway for blood fetus  mother
  38. 38. Fetal Circulation Umbilical vein brings O2 blood from placenta  liver and Ductus Venosus  Inferior Vena Cava  R Atrium
  39. 39. Fetal Circulation Foramen ovale - hole in atrial septum allows mixing of blood in heart (eventually becomes fossa ovalis)
  40. 40. At Birth Umbilical arteries  medial umbilical ligaments Umbilical vein  ligamentum teres Ductus venosus  ligamentum venosum
  41. 41. At Birth Placenta is “afterbirth” Foramen ovalis closes  fossa ovale Ductus arteriosus  ligamentum arteriosum
  42. 42. Aging Stiffening of aorta Loss of cardiac muscle strength  Reduced CO & increased systolic pressure Coronary artery disease (CAD) Congestive heart failure Atherosclerosis

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