Final answer:
When scared, the body's 'fight-or-flight' response increases blood pressure and heart contractility, improving blood flow to allow a quick reaction to threats. This physiological change is beneficial in short-term stressful situations but can lead to hypertension if the stress is prolonged or frequent.
Step-by-step explanation:
When a person is scared, there is a physiological response known as the 'fight-or-flight' reaction, which is activated by the sympathetic nervous system. During this response, the adrenal glands release stress hormones like adrenaline, which leads to an increase in blood pressure. Elevated blood pressure causes the heart to beat faster, increasing heart contractility and ultimately enhancing blood flow to vital organs and muscles.
This physiological change serves a practical purpose; it prepares the body to either confront the threat (fight) or flee from it (flight). Higher blood pressure and increased blood flow ensure that muscles receive more oxygen and nutrients, which are crucial for a quick response. As a result, the cardiac response to fear includes increased cardiac output and stroke volume, which adapt to the demands of the body during stressful situations.
However, it's important to note that prolonged stress or frequent activation of this response without actual physical exertion can lead to hypertension, also known as high blood pressure, which is a serious health condition that can damage the heart and blood vessels over time.