Vasoconstrictor Agents<br />Norepinephrine and Epinephrine<br />Norepinephrine is an especially powerful vasoconstrictor h...
Angiotensin II<br />Angiotensin II is powerful vasoconstrictor substance<br />The effect of angiotensin II is to constrict...
Vasopressin<br />Vasopressin, also called antidiuretic hormone, one of the body's most potent vascular constrictor substan...
Other chemical influences on blood flow<br />Histamine<br />Most of the histamine is derived from mast cells in the damage...
Bradykinin<br />Bradykinin causes both powerful arteriolar dilation and increased capillary permeability<br />Bradykinin p...
Vascular Control by Ions and Other Chemical Factors<br />An increase in calcium ion concentration causes vasoconstriction<...
An increase in hydrogen ion concentration causes dilation of the arterioles<br />An increase in carbon dioxide concentrati...
Pharmacologic Stimuli that Cause Contraction or Relaxation of Vascular Smooth Muscle<br />Vasoconstrictors<br />Norepineph...
Distribution of Blood in the Body Organs<br />
Flow rate in muscle<br />Skeletal muscle constitute 40 – 45% body weight<br />5 ml/min/100 g to 80-100 ml/min/100 g<br />I...
Control of blood flow through the skeletal muscle<br />Local regulation- decrease oxygen in muscle greatly enhance flow<br...
Nervous control of muscle blood flow<br />Skeletal muscles are provided with sympathetic vasoconstrictor nerves<br />Sympa...
Total Body Circulatory Readjustments During Exercise<br />Three major effects occur during exercise <br />(1) mass dischar...
Effects of Mass Sympathetic Discharge<br />Three major circulatory effects result<br />The heart is stimulated to greatly ...
Effects of Mass Sympathetic Discharge<br />Most of the arterioles of the peripheral circulation are strongly contracted, e...
The muscle walls of the veins are contracted powerfully, which greatly increases the mean systemic filling pressure<br />T...
Effect of Arterial Pressure Rise<br />Increases force to drive blood (by 30%)<br />Dilates vessels, decreasing resistance ...
Local vs Whole Body Exercise<br />Local (e.g. lifting weight): Mainly vasoconstriction – high increase in BP (up to 170 mm...
Effects of Exercise on Muscle Circulation<br />Increased heart rate & pumping strength<br />Aterioles constricted in most ...
12-15<br />
Normal Coronary Blood Flow<br />The resting coronary blood flow in the human being averages about 225 ml/min, which is abo...
Coronary Circulation<br />Left coronary artery supplies the anterior and left lateral of the left ventricle<br />Right cor...
Coronary Circulation: Venous Supply<br />Most of the coronary venous blood from the left ventricular muscle return to the ...
Phasic changes in coronary blood flow during systole and diastole<br />
Left coronary blood flow<br />Right coronary blood flow<br />
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Lec60

  1. 1. Vasoconstrictor Agents<br />Norepinephrine and Epinephrine<br />Norepinephrine is an especially powerful vasoconstrictor hormone; epinephrine is less so<br />When the sympathetic nervous system is stimulated, the sympathetic nerve endings in the individual tissues release norepinephrine, which excites the heart and contracts the veins and arterioles<br />In addition, the sympathetic nerves to the adrenal medullae cause these glands to secrete both norepinephrine and epinephrine into the blood<br />
  2. 2. Angiotensin II<br />Angiotensin II is powerful vasoconstrictor substance<br />The effect of angiotensin II is to constrict powerfully the small arterioles and decreases the blood flow <br />Angiotensin II increases the total peripheral resistance, thereby increasing the arterial pressure<br />
  3. 3. Vasopressin<br />Vasopressin, also called antidiuretic hormone, one of the body's most potent vascular constrictor substances<br />The concentration of circulating blood vasopressin after severe hemorrhage can rise high enough to increase the arterial pressure<br />In many instances this canbringthe arterial pressure almost back up to normal<br />
  4. 4. Other chemical influences on blood flow<br />Histamine<br />Most of the histamine is derived from mast cells in the damaged tissues <br />Histamine has a powerful vasodilator<br />Has the ability to increase greatly capillary porosity, allowing leakage of both fluid and plasma protein into the tissues<br />
  5. 5. Bradykinin<br />Bradykinin causes both powerful arteriolar dilation and increased capillary permeability<br />Bradykinin play special roles in regulating blood flow and capillary leakage of fluids in inflamed tissues<br />
  6. 6. Vascular Control by Ions and Other Chemical Factors<br />An increase in calcium ion concentration causes vasoconstriction<br />An increase in potassium ion concentration causes vasodilation<br />An increase in magnesium ion concentration causes powerful vasodilation<br />
  7. 7. An increase in hydrogen ion concentration causes dilation of the arterioles<br />An increase in carbon dioxide concentration causes moderate vasodilation in most tissues, but marked vasodilation in the brain<br />Vascular Control by Ions and Other Chemical Factors<br />
  8. 8. Pharmacologic Stimuli that Cause Contraction or Relaxation of Vascular Smooth Muscle<br />Vasoconstrictors<br />Norepinephrine and epinephrine<br />Endothelin<br />Angiotensin II<br />Vasopressin<br />Calcium<br />Vasodilator agents<br />Histamine<br />Adenosine<br />Nitric Oxide (NO)<br />Carbon Dioxide<br />Potassium<br />Magnesium<br />Hydrogen Ion<br />Prostaglandins<br />Bradykinin<br />
  9. 9. Distribution of Blood in the Body Organs<br />
  10. 10. Flow rate in muscle<br />Skeletal muscle constitute 40 – 45% body weight<br />5 ml/min/100 g to 80-100 ml/min/100 g<br />Intermittent as a result of contraction of muscle<br />Exercise opens capillaries<br />
  11. 11. Control of blood flow through the skeletal muscle<br />Local regulation- decrease oxygen in muscle greatly enhance flow<br />During muscle activity, muscle uses oxygen thus decreasing oxygen in the tissue fluid<br />Vasodilator – adenosine, potassium ions, carbon dioxide<br />
  12. 12. Nervous control of muscle blood flow<br />Skeletal muscles are provided with sympathetic vasoconstrictor nerves<br />Sympathetic vasoconstrictor secrete norepinephrine in their nerve ending (important during shock and stress)<br />Epinephrine – secreted by adrenal medullae gives vasodilator effect during exercise<br />
  13. 13. Total Body Circulatory Readjustments During Exercise<br />Three major effects occur during exercise <br />(1) mass discharge of the sympathetic nervous system throughout the body<br />(2) increase in arterial pressure<br />(3) increase in cardiac output <br />
  14. 14. Effects of Mass Sympathetic Discharge<br />Three major circulatory effects result<br />The heart is stimulated to greatly increased heart rate and increased pumping strength as a result of the sympathetic drive to the heart plus release of the heart from normal parasympathetic inhibition<br />
  15. 15. Effects of Mass Sympathetic Discharge<br />Most of the arterioles of the peripheral circulation are strongly contracted, except for the arterioles in the active muscles, which are strongly vasodilated by the local vasodilator<br />Two of the peripheral circulatory systems, the coronary and cerebral systems, are spared this vasoconstrictor effect<br />
  16. 16. The muscle walls of the veins are contracted powerfully, which greatly increases the mean systemic filling pressure<br />This is one of the most important factors in promoting increase in venous return of blood to the heart and, therefore, in increasing the cardiac output <br />Effects of Mass Sympathetic Discharge<br />
  17. 17. Effect of Arterial Pressure Rise<br />Increases force to drive blood (by 30%)<br />Dilates vessels, decreasing resistance (can double flow rate)<br />
  18. 18. Local vs Whole Body Exercise<br />Local (e.g. lifting weight): Mainly vasoconstriction – high increase in BP (up to 170 mm Hg).<br />Whole body (e.g. running): vasodilation in a large mass of muscles leads to more slight increase in BP (maybe 20-40 mm Hg).<br />
  19. 19. Effects of Exercise on Muscle Circulation<br />Increased heart rate & pumping strength<br />Aterioles constricted in most of periphery (but not in coronary and cerebral systems).<br />Active muscle arterioles dilated<br />Vein muscle walls constricted (increased filling pressure, hence, increased venous return).<br />
  20. 20. 12-15<br />
  21. 21. Normal Coronary Blood Flow<br />The resting coronary blood flow in the human being averages about 225 ml/min, which is about 4 to 5 per cent of the total cardiac output <br />Coronary circulation is the functional blood supply to the heart muscle itself<br />Collateral routes ensure blood delivery to heart even if major vessels are occluded<br />
  22. 22. Coronary Circulation<br />Left coronary artery supplies the anterior and left lateral of the left ventricle<br />Right coronary artery supplies most of the right ventricle and posterior part of the left ventricle in 80 to 90% of the people<br />
  23. 23. Coronary Circulation: Venous Supply<br />Most of the coronary venous blood from the left ventricular muscle return to the right atrium by coronary sinus<br />From the right ventricular muscle return through small anterior cardiac veins<br />Very small amount of coronary venous blood flows back into the heart through thebesian veins<br />
  24. 24. Phasic changes in coronary blood flow during systole and diastole<br />
  25. 25. Left coronary blood flow<br />Right coronary blood flow<br />

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