Respiratory Muscles

Definition

Respiratory muscles are the skeletal muscles responsible for the mechanical process of breathing, allowing for the inhalation and exhalation of air. These muscles play a crucial role in the respiratory system by facilitating the expansion and contraction of the thoracic cavity, enabling the lungs to draw in and expel air.

5 Must Know Facts For Your Next Test

1. The diaphragm is the primary respiratory muscle, responsible for approximately 75% of the volume change during normal breathing.
2. Contraction of the diaphragm increases the volume of the thoracic cavity, resulting in a decrease in intrathoracic pressure and the inhalation of air.
3. The intercostal muscles work in coordination with the diaphragm, contracting during inspiration to further expand the thoracic cavity.
4. Accessory respiratory muscles, such as the sternocleidomastoid and scalene muscles, can be recruited to assist in breathing during exercise or respiratory distress.
5. The abdominal muscles play a crucial role in exhalation by contracting and increasing intra-abdominal pressure, which in turn pushes the diaphragm upward and expels air from the lungs.

Review Questions

• Explain the role of the diaphragm in the respiratory process.
  • The diaphragm is the primary respiratory muscle, responsible for approximately 75% of the volume change during normal breathing. When the diaphragm contracts, it flattens and moves downward, increasing the volume of the thoracic cavity. This decrease in intrathoracic pressure causes air to be drawn into the lungs, facilitating inspiration. Conversely, the relaxation of the diaphragm allows the abdominal muscles to push it upward, decreasing the volume of the thoracic cavity and causing air to be expelled from the lungs during exhalation.
• Describe the function of the intercostal muscles in relation to the respiratory process.
  • The intercostal muscles, located between the ribs, work in coordination with the diaphragm to facilitate the expansion and contraction of the thoracic cavity during breathing. During inspiration, the intercostal muscles contract, pulling the ribs upward and outward, further increasing the volume of the thoracic cavity and aiding the diaphragm in drawing air into the lungs. Conversely, the relaxation of the intercostal muscles during exhalation allows the ribs to move downward and inward, decreasing the volume of the thoracic cavity and assisting in the expulsion of air from the lungs.
• Analyze the role of the accessory respiratory muscles in the respiratory process, particularly during increased respiratory demands.
  • While the diaphragm and intercostal muscles are the primary respiratory muscles, the body can recruit additional accessory respiratory muscles, such as the sternocleidomastoid, scalene, and abdominal muscles, to assist in breathing during increased respiratory demands. During exercise or respiratory distress, these accessory muscles can contract to further expand the thoracic cavity, increasing the volume of air that can be drawn into the lungs. The abdominal muscles, in particular, play a crucial role in exhalation by contracting and increasing intra-abdominal pressure, which in turn pushes the diaphragm upward and expels air from the lungs. The utilization of these accessory respiratory muscles demonstrates the body's adaptability in meeting varying respiratory needs.

Related terms

Diaphragm:

The dome-shaped muscle that separates the thoracic and abdominal cavities, playing a primary role in inspiration by contracting and flattening to increase the volume of the thoracic cavity.

Intercostal Muscles:

The muscles located between the ribs that assist in the expansion and contraction of the thoracic cavity during breathing.

Accessory Respiratory Muscles: Additional muscles, such as the sternocleidomastoid, scalene, and abdominal muscles, that can be recruited to aid in breathing during increased respiratory demands.