Question

The ventilation movements of the lungs in mammals are governed by (a) muscular walls of lung (b) diaphragm (c) coastal muscles (d) both (b) and \((c)\).

Short answer

The correct answer is (d) both (b) the diaphragm and (c) coastal muscles are responsible for the lung ventilation movements in mammals.

Step-by-step solution

Understanding the Functioning of Mammalian Ventilation

The process of ventilation in mammals involves the movement of air into and out of the lungs. This process is controlled by various muscular structures that change the volume of the thoracic cavity, creating the negative pressure necessary for inhalation and positive pressure for exhalation.

Identifying the Muscular Structures Involved

The main muscular structures that facilitate the ventilation process are the diaphragm and the intercostal muscles (also known as coastal muscles). The diaphragm is a large, dome-shaped muscle at the base of the lungs, while the intercostal muscles are located between the ribs.

Determine the Correct Answer

Given the options, we can rule out (a) because the muscular walls of the lung are not responsible for the ventilation movements. Among the remaining options, both the diaphragm and the intercostal muscles are directly involved in the process of breathing. Therefore, (d) 'both (b) and (c)' is the correct answer.

Key concepts

Diaphragm Function in Breathing

The diaphragm plays a vital role in the mammalian ventilation process. When we inhale, the diaphragm contracts and flattens, which increases the volume of the thoracic cavity. This expansion reduces the pressure inside the cavity compared to the outside air pressure, causing air to rush into the lungs for equilibrium. During exhalation, the diaphragm relaxes and adopts a dome-shaped form, decreasing the thoracic cavity's volume and pushing air out of the lungs.

Understanding the diaphragm function is crucial for comprehending how breathing modulation can affect overall health. Controlled breathing exercises, often employed in practices like yoga, leverage the diaphragm's movement to promote relaxation and enhance lung capacity.

Intercostal Muscles in Respiration

The intercostal muscles encompass two major types: the external and internal intercostals. The external intercostal muscles are responsible for elevating the ribs during inhalation, while the internal intercostals aid in depressing the ribs during forced exhalation.

The harmonious coordination between the diaphragm and the intercostal muscles ensures a smooth respiratory cycle. By altering the rib cage's dimensions, these muscles collectively impact the air pressure within the lungs. Understanding this coordination provides insight into the importance of proper posture during breathing, as slouching can impair the intercostal muscles' effectiveness and thus the efficiency of respiration.

Thoracic Cavity Changes During Ventilation

As the primary site of lung expansion and contraction, the thoracic cavity undergoes significant changes during ventilation. When the diaphragm and intercostal muscles contract, the thoracic cavity's volume increases, decreasing the internal pressure and allowing air to flow into the lungs (inhalation). Conversely, during exhalation, these muscles relax, the cavity's volume decreases, and the internal pressure rises, expelling air from the lungs.

To maximize the efficiency of gas exchange in the lungs, it is essential to maintain the resilience of the thoracic cavity and muscular strength through regular exercise. This not only aids in optimum breathing but can also contribute to better posture and alignment, reducing the risk of respiratory complications.