1. Sympathetic nervous system constrict the arteries and arterioles which increases the vascular resistance and decreases the blood flow . The increased vascular resistance causes the arterial pressure to increase . During extensive stress , the sympathetic system increases the blood flow to important stress response organs and the blood flow in high pressure thus decreasing or restricting the blood flow to other organs .2.Beta 1 antagonist is used to treat high blood pressure and high heart rate . It is used to treat angina , fibrillation or during heart failure etc. Beta 1 antagonist should not be used if a person is having chronically lower heart rate because if beta antagonist is given it can cause more dizziness and lightheadedness to a person . It can leads to death or trauma to a person .