Change in Heart Rate

Anatomy and Physiology BOW
Pick three factors that can change your heart rate. How do they change your heart rate? (i.e. faster, stronger, slower, weaker) For each give another system affected by the change in heart rate.

1. Neural and hormonal effects:
Intrinsic and extrinsic controls regulate the heart rate. Intrinsic regulation of heart rate is the heart's self-regulating tissue and maintenance of its own rhythm. Extrinsic controls are those that come from hormonal responses and commands from the nervous system. Extrinsic regulation can cause the heart rate to change rapidly because of chemicals that circular in the blood or by direct action of nerves that go to the heart.
There is no cardiovascular or cardio respiratory change as a result of this change in heart rate; it's simply the affect on the heart of chemicals and nerves responding to an external experience.
The cardiovascular control center for the body is located in the ventro-lateral medulla. Here heart rate slows if activated by the cardio inhibitory center in the medulla or speeds up if activated by the cardio accelerator.
Another system affected by this change is the endocrine system.

2. Internal body changes:
Lack of sleep, lack of food, low blood sugar, reactions to different foods, and other internal factors may speed up or low down the heart rate. Emotions can also have an effect on the heart rate. Fear or anxiety, for example, speed up the heart rate. Relaxation can slow down the heart beat.
Another system affected by this internal body is the respiratory system because the breathing changes. The immune system is also affected because lack of eating and sleep will weaken the immune system.

3. Caffeine:
The presence of caffeine in the body tends to speed up the heart rate. This is because caffeine is a stimulant, which means that it is a chemical that makes the heart beat faster. This results in the person who takes the caffeine to be more awake, as their body is taking in more oxygen than usual because of the faster heart beat.
Another system affected by caffeine is the muscle system, which receives more blood and oxygen supply from the increased amounts of pumping.




Source: http://www.heartmonitors.com/exercisetips/changing_heartrate.htm