Question

Robert decides to go for a run when he gets home from school. As he begins running, his breathing rate starts to increase. What are the mechanisms that cause his breathing rate to increase?

A.
When carbon dioxide levels in the blood decrease, the respiratory center sends signals to the alveoli to increase the volume that they expand.
B.
When oxygen levels in the blood decrease, the respiratory center sends signals to the diaphragm to increase the rate at which it contracts and relaxes.
C.
The respiratory control center senses the need for more oxygen, which causes the trachea to push and pull air more forcefully.
D.
The diaphragm senses the need for more oxygen, which causes it to expand and contract more quickly in order to inflate and deflate the lungs.

Answer 1

The correct answer is option B which is low level of oxygen in blood is sensed by the brain respiratory center which signals the diaphragm to increase the rate at which it contracts and relaxes.

Step-by-step explanation:

• As we are running, our muscles are are using great amount of energy relative to energy productions in these cells. So these cells start breaking the glucose at higher rate to meet up energy needs.
• So oxygen is used in respiration and its amount suddenly decrease.
• to increase this oxygen level brain signals to raise the breathing rate.

Answer 2

When a person starts exercising (running) the increase in energy expenditure causes an elevation of oxygen consumption and carbon dioxide production. To compensate for this the respiratory control center senses the LOW oxygen level in blood and the HIGH carbon dioxide level and signals the diaphragm to contract and relax more often (INCREASE THE RATE).

The answer is B