You are hiking in the mountains on a warm summer day. As you are walking up a st

Question

You are hiking in the mountains on a warm summer day. As you are walking up a steep incline, your leg muscles are waking pretty hard. They need to produce a lot more ATP than usual in order to propel you upward. Your breathing becomes deeper and more rapid as you work to bring in more air. You also notice that you are getting warm and starting to sweat You have water with you and decide to stop for a water and snack break. Your snack consists of a power bar that contains a nice mix of carbs. proteins, and lipids. Just what your body needs! As you sit and replenish your energy and water, you marvel at the beauty at your surrounds and feel a sense of appreciation that your body is healthy and able to adjust its activities to meet your ongoing needs. Oxygen is needed for ATP production by your muscles. Describe how the lungs are working to increase the inflow of fresh air. so that more oxygen can be delivered to your muscles. Describe a regulatory mechanism that would explain why your breathing became deeper and more rapid while you were hiking.

Explanation / Answer

1).

Exercise (for example, hiking) induces stress response. The two major hormones that are released in response to stress are, adrenaline and cortisol. Adrenaline increases the blood glucose levels to meet the metabolic demands. Increased metabolic rate increases the heat production, which is exchanged with the external environment. This occurs by increased peripheral circulation caused by adrenaline and noradrenaline. Sweat occurs during this process.

The cortisol and adrenaline increase the blood glucose levels necessary for the ATP production. As the metabolism increases, the CO2 production increases. The change in PO2 and PCO2 levels in the alveoli is sensed by the nerve endings that activate or inactivate respiratory center. The central chemoreceptors in the medulla oblongata respond primarily to increased carbon dioxide levels rather than the decreased oxygen levels. Increased PCO2 activates the respiratory center and increase the rate of respiration. So, more oxygen is delivered to the muscles. The adrenaline also increases the heart rate, cardiac output, relaxation of bronchial smooth muscle (thus, increased rate of respiration).

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