Describe the cause and mechanism of anticipatory rise in heart-rate and the effect it has on a marathon runner who is waiting on the start line for their race to start(5 Points)

The anticipatory rise in heart rate is caused by the activation of the sympathetic nervous system in response to the anticipation of physical activity or stress. This mechanism is commonly known as the "fight or flight" response.

1. The brain, specifically the hypothalamus, detects the upcoming physical activity or stress and sends signals to the autonomic nervous system.
2. The autonomic nervous system, which is responsible for regulating involuntary bodily functions, activates the sympathetic branch.
3. The sympathetic branch releases stress hormones, such as adrenaline and noradrenaline, into the bloodstream.
4. These stress hormones bind to receptors on the heart muscle cells, leading to an increase in heart rate.
5. The increased heart rate ensures that more oxygenated blood is delivered to the muscles, preparing the body for the upcoming physical exertion.

For a marathon runner waiting on the start line, the anticipatory rise in heart rate has several effects:

1. Increased blood flow: The increased heart rate allows for a greater volume of blood to be pumped with each heartbeat, ensuring that the muscles receive an adequate supply of oxygen and nutrients.
2. Enhanced alertness: The release of stress hormones also leads to increased mental alertness and focus, helping the runner to be more mentally prepared for the race.
3. Improved performance: The anticipatory rise in heart rate primes the body for physical activity, allowing the runner to start the race with a higher level of readiness and potentially improving their overall performance.
4. Increased energy availability: The increased heart rate also stimulates the release of stored energy sources, such as glycogen, to provide the necessary fuel for the muscles during the race.
5. Heightened arousal: The anticipatory rise in heart rate can also lead to feelings of excitement and anticipation, which can help motivate the runner and enhance their overall race experience.

Overall, the anticipatory rise in heart rate plays a crucial role in preparing the marathon runner for the physical demands of the race, ensuring optimal performance and readiness.