1.2.3 Mechanism of Breathing

• The diaphragm is a large, dome-shaped muscle located at the base of the chest cavity
• During inhalation, the diaphragm contracts and moves downwards
• Match the breathing action with its effect on chest cavity volume and pressure:

  Inhalation ↔️ Volume increases, pressure decreases

  Exhalation ↔️ Volume decreases, pressure increases
• Where are the intercostal muscles located?

  Between the ribs
• What happens to the diaphragm during inhalation?

  It contracts and flattens
• What happens to the volume of the chest cavity during inhalation?

  It increases
• What is the main function of exhalation?

  To expel air
• Exhalation occurs when the rib cage returns to its resting position and the diaphragm returns to its dome shape
• Match the action with the movement of intercostal muscles and the diaphragm:

  Inhalation ↔️ Intercostal muscles contract, diaphragm moves downwards

  Exhalation ↔️ Intercostal muscles relax, diaphragm returns to dome shape
• During exhalation, the diaphragm relaxes and moves upwards
• During inhalation, the diaphragm and intercostal muscles contract, causing the chest cavity to expand
• What happens to the diaphragm during inhalation?

  It contracts and flattens
• Match the action of breathing with the corresponding movement of intercostal muscles and the diaphragm:

  Inhalation ↔️ Intercostal muscles contract, diaphragm moves downwards

  Exhalation ↔️ Intercostal muscles relax, diaphragm returns to dome shape
• Order the events that occur during air movement in breathing

  1️⃣ Diaphragm contracts and moves downwards

  2️⃣ Intercostal muscles lift the rib cage

  3️⃣ Chest cavity volume increases

  4️⃣ Chest cavity pressure decreases

  5️⃣ Air enters lungs

  6️⃣ Diaphragm relaxes and rises

  7️⃣ Air exits lungs
• What happens to chest cavity volume during exhalation?

  Decreases
• What are the two main processes involved in breathing?

  Inhalation and exhalation
• What is the typical value of tidal volume in healthy adults?

  500 mL
• What causes air to be drawn into the lungs during inhalation?

  Decreased chest cavity pressure
• Where is the diaphragm located in the body?

  Base of the chest cavity
• Steps of the diaphragm movement and air movement during inhalation and exhalation

  1️⃣ Inhalation: Diaphragm contracts and flattens

  2️⃣ Inhalation: Chest cavity volume increases

  3️⃣ Inhalation: Chest cavity pressure decreases

  4️⃣ Exhalation: Diaphragm relaxes and rises

  5️⃣ Exhalation: Chest cavity volume decreases

  6️⃣ Exhalation: Chest cavity pressure increases
• What two muscle groups are primarily responsible for the cyclic process of breathing?

  Diaphragm and intercostal muscles
• During exhalation, the chest cavity volume decreases and the pressure increases.
• During exhalation, the intercostal muscles relax, allowing the rib cage to return to its resting position.
• During inhalation, air is drawn into the lungs due to decreased pressure in the chest cavity.


  True
• Match the breathing action with the corresponding changes in the respiratory system:

  Inhalation ↔️ Chest cavity volume increases ||| Air enters lungs

  Exhalation ↔️ Chest cavity volume decreases ||| Air exits lungs
• Order the events during inhalation:

  1️⃣ Diaphragm contracts and moves downwards

  2️⃣ Intercostal muscles contract to lift rib cage

  3️⃣ Chest cavity volume increases

  4️⃣ Chest cavity pressure decreases

  5️⃣ Air is drawn into the lungs
• Which brain region initiates and regulates breathing?

  Medulla oblongata
• Match the respiratory component with its action:

  Medulla Oblongata ↔️ Sends signals to breathing muscles

  Phrenic Nerve ↔️ Transmits signals to diaphragm

  Intercostal Nerves ↔️ Stimulate intercostal muscles
• Decreased O2 levels in the blood will cause the breathing rate to decrease.

  False
• What stimulus do peripheral chemoreceptors primarily detect?

  Decreased O2 levels
• What happens to the volume and pressure of the chest cavity during inhalation?

  Volume increases, pressure decreases
• Inhalation and exhalation are the two key processes that make up the mechanism of breathing


  True
• The diaphragm separates the thoracic and abdominal cavities


  True
• The diaphragm is located at the base of the chest cavity and is shaped like a dome
• What happens to chest cavity pressure during exhalation?

  It increases
• Exhalation occurs when the diaphragm relaxes
• During exhalation, air moves out of the lungs due to increased pressure
• Tidal volume is the volume of air moved during a normal breath
• Match the respiratory volume with its description:

  Tidal Volume ↔️ Volume of air moved during a normal breath

  Inspiratory Reserve Volume ↔️ Additional air that can be inhaled after a normal inhalation

  Expiratory Reserve Volume ↔️ Additional air that can be exhaled after a normal exhalation

  Residual Volume ↔️ Air remaining in the lungs after maximum exhalation
• The diaphragm and intercostal muscles relax during inhalation.

  False