Blood-pressure is measured in two stages.
(1) Systolic Pressure:- It is the higher limit of blood pressure that shows the state of heart (systole) contraction for man this limit is 120 mm Hg (normal)
(2) Diastolic pressure:- It is the lower limit of B.P. that shows the state of heart relaxation (expansion = Diastole) for man this limit is 80 mm Hg (normal)
The instrument by which we can measure B.P. is called sphygmomanometer.
Sphygmomanometer
In man B.P. is measured in the brachial artery of arm. [- Normal B.P. of a healthy person is 120/80 mm Hg.]
Hales measured B.P. in horse first of all.
(1) Exercise:- At the time of physical labour. B.P. is increased.
(2) Emotions and Excitement:- In the state of excitement or emotions B.P. is increased in man. At the time of Adrenal secretion at the time of fear and in some hereditary conditions B.P. is increased.
(3) Contraction of Blood Vessels:- B.P. is increased when contraction takes place in arteries and blood capillaries.
(4) Body posture:- In a laying (relaxing) person B.P. is low as compared to a standing man
(5) Sex:- In women, B.P. is slightly low as compared to men.
(6) Obesity:- In obese persons B.P. is increased.
(7) Age : B.P. increases as the age advances due to increase in vasomotor tone.
Note: Pulse is felt in the radial artery present in the wrist of a man. It is also felt in the artery of neck region. The graph of pulse of an artery is marked by an instrument that is called sphygmograph. Pulse pressure is the Pressure difference which generates a pulse. This is systolic minus diastolic B.P.
Secondary hypertension is due to an underlying cause like Hormonal or obstructional. Primary hypertension is also called essential hypertension. 90% of the hypertensive patients suffer from this type of hypertension.
It is caused by several factors like arteriosclerosis, atherosclerosis, varicose veins, obesity, etc.
High blood pressure must be managed. Excessive high blood pressure, say 220/120 mm Hg. is dangerous as it may cause haemorrhages in different parts of body causing blindness (due to optic arteries), nephritis (renal artery), brain stroke or CVA (due to rupturing of cerebral artery). Brain stroke may cause loss of speech, paralysis and other malfunctions of the body. Continued hypertension also affects muscles and valves of the heart. The damage is called hypertensive heart disease. Therefore, regular treatment with controlled diet and reduced salt intake should be undertaken. Excessive physical exercise should be avoided.
Low blood pressure results in weakness, dizziness, blurred vision, etc. It can be corrected only after knowing the cause. However, temporary relief can be obtained through intake of glucose & salt rich drink.
| Atherosclerosis | Arteriosclerosis |
1. | Deposition of lipids (Cholesterol) on the walls (such depositions are called atheromatous plaque) | Hardening of arteries due to thickening along with deposition of calcium salts with cholesterol |
2. | Takes place in Lumen of large and medium size arteries of body | Can take place in medium to small arteries of limbs |
3. | Plaques are formed due to proliferation of smooth muscles of the inner wall of arteries (due to platelet derived growth factors) | No plaque formation occurs, but the arteries are stiff and rigid due to calcification. |
4. | Encroachment of Lumen of artery is present | There is not much encroachment of Lumen |
5. | Artery Lumen may get blocked resulting in no blood supply. | Artery becomes hard, looses its capacity of distention and may rupture |
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