Blood pressure, Biology


  • Is the result of the sum of

                (i) Osmotic colloidal pressure of blood
                (ii) Elastic recoil of blood vessel's wall.
                (iii) Pumping force of heart.

  • First measured by British physiologist Stephan Hales (1733) in carotid artery of mare (female horse).
  • In human it was first measured by Vaivre (1856) using Ludwig mercury manometer.
  • Riva Rocci (1896) discovered sphygmomanometer, the instrument to measure B.P. 120
  • Normal range of B.P. is  80 mm Hg., (120 mm Hg = systolic pressure; 80 mmHg = diastolic pressure)
  • The differences between systolic and diastolic pressure is called pulse pressure (40 mmHg) 80 mmHg + age in years
  • It is is calculated as : B.P. = 50 mmHg + age in years
  • But, in any age it shouldn't exceed 150/100 mmHg and shouldn't be below 80/50 mmHg.
  • The abnormal rise in B.P. (hypertension) occurs due to defect of any of the above three components with increasing age the rigidity of arterial wall causes high B.P.
  • Hypotension (low B.P.) may be due to chronic vasodilation, anemia, blood loss and improper heart action.
  • B.P. is slightly lower in female than male until the menopause.
  • During sleep the pressure falls by 20-30 mmHg and may reach 180-200 during exercise.
Posted Date: 10/2/2012 3:09:00 AM | Location : United States

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