Use the words inspiration and expiration to describe the part of the breathing cycle that occurs as a result of each of the following:
a. The diaphragm contracts.

Verified step by step guidance

1. Step 1: Understand the terms 'inspiration' and 'expiration'. Inspiration refers to the process of inhaling air into the lungs, while expiration refers to the process of exhaling air out of the lungs.
2. Step 2: Recall the role of the diaphragm in breathing. The diaphragm is a dome-shaped muscle located below the lungs that plays a key role in the breathing process.
3. Step 3: Analyze what happens when the diaphragm contracts. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity (the space where the lungs are located).
4. Step 4: Relate the increase in thoracic cavity volume to air movement. As the thoracic cavity volume increases, the pressure inside the lungs decreases (based on Boyle's Law: pressure and volume are inversely related). This pressure drop causes air to flow into the lungs.
5. Step 5: Conclude that the contraction of the diaphragm is associated with inspiration, as it facilitates the intake of air into the lungs.

Key Concepts

Diaphragm Function

The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity. When it contracts, it flattens and moves downward, increasing the volume of the thoracic cavity. This action creates a negative pressure that draws air into the lungs, facilitating the process of inspiration.

Inspiration

Inspiration is the phase of the breathing cycle where air is drawn into the lungs. It occurs when the diaphragm contracts and the intercostal muscles expand the rib cage, leading to a decrease in internal pressure compared to the external atmosphere. This pressure difference allows air to flow into the lungs, supplying oxygen to the body.

Expiration

Expiration is the phase of the breathing cycle where air is expelled from the lungs. It typically occurs when the diaphragm relaxes and returns to its dome shape, decreasing the thoracic cavity's volume. This increase in internal pressure forces air out of the lungs, removing carbon dioxide and other gases from the body.