Which of the following statements is not true about blood pressure ?

Options

A. Blood pressure is measured with an instrument called sphygmomanometer
B. If the blood pressure of an individual is 140/90 mm Hg or higher, it shows hypertension
C. The normal systolic pressure is 120 mm Hg and diastolic pressure is 80 mm Hg.
D. Hypertension is caused by vasodilation which results in increased resistance to blood flow

Answer

To determine which statement is not true about blood pressure, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Understanding Blood Pressure Measurement**:
- Blood pressure is measured using an instrument called a sphygmomanometer. This statement is true. The sphygmomanometer can be manual or digital.

2. **Hypertension Definition**:
- Hypertension is defined as having a blood pressure of 140/90 mm Hg or higher. This statement is also true. Therefore, this option cannot be the answer.

3. **Normal Blood Pressure Values**:
- The normal systolic pressure is 120 mm Hg and the diastolic pressure is 80 mm Hg. This statement is true as well. Thus, this option is not the answer.

4. **Causes of Hypertension**:
- The statement claims that hypertension is caused by vasodilation, which results in increased resistance to blood flow. This statement is not true. Hypertension is actually caused by vasoconstriction, which narrows the blood vessels and increases resistance to blood flow.

5. **Conclusion**:
- The statement that is not true about blood pressure is: "Hypertension is caused by vasodilation which results in increased resistance." Therefore, this is the incorrect statement.

### Final Answer:
The statement that is not true about blood pressure is: **"Hypertension is caused by vasodilation which results in increased resistance."**

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