Every cell in the body needs a constant supply of blood to bring in oxygen and nutrients to remove waste products. Symptoms are masked since everyday fluctuations of blood pressure are usually minor and well compensated for by the body. A gradual rise in blood pressure over month and years is particularly dangerous, as it slips by the body's warning signal which are: nervousness, headaches, dizziness, nosebleeds and flushed cheeks. Stress, anxiety, anger and physical activity cause substantial changes in blood pressure readings.