Final answer:
The primary stimulus to breathe is an increase in blood carbon dioxide levels (Pco2), which is sensed by the brain's respiratory centers. This increase in Pco2 leads to a higher ventilatory response in order to expel carbon dioxide and regulate blood pH. Breathing patterns are also influenced by laws of gas behavior and can be modulated by various activities, such as exercise.
Step-by-step explanation:
The primary drive or impulse to breathe is triggered by an increase in carbon dioxide levels (Pco2) in the blood. This condition is known as hypercapnia. Both the respiratory rate and depth of breathing are controlled by the respiratory centers within the brain, and these centers are highly sensitive to the levels of carbon dioxide and the pH of the blood. An increase in carbon dioxide levels can lead to a more acidic blood pH, stimulating the central and peripheral chemoreceptors to trigger an increase in ventilation. This increase in ventilation serves to expel carbon dioxide from the body more quickly and normalize blood pH.
To further understand the control of breathing, it's helpful to note that the behavior of gases, including respiration, can be explained by Dalton's law and Henry's law. According to Dalton's law, each gas in a mixture exerts partial pressure independently of others. Henry's law posits that a gas's solubility in a liquid is dictated by its partial pressure. With oxygen having a higher partial pressure in the alveoli compared to the capillary blood, it diffuses into the bloodstream, whereas carbon dioxide diffuses from the blood into the alveoli where its partial pressure is lower.
The body may adjust its respiratory function in response to different situations. For example, exercise results in hyperpnea, an increase in the rate and depth of ventilation due to neural mechanisms including psychological stimuli and motor neuron activation, which prepares the body to meet increased oxygen demands.