5.2

The Respiratory System

• The respiratory system provides the body with oxygen, crucial for energy production.
• Without oxygen, the body would cease to function within minutes.
• The respiratory system collaborates with the circulatory system to deliver oxygen to, and remove carbon dioxide from, all cells.

Four Processes

• Breathing (Inhalation/Exhalation):

  • Inhalation - Takes in oxygen:
    • The rib cage expands, and the diaphragm contracts (moves downward).
    • This increases the chest cavity's volume and decreases the air pressure within.
    • Air rushes into the lungs.
  • Exhalation - Releases carbon dioxide:
    • The rib cage and diaphragm return to their resting positions.
    • This decreases the chest cavity's volume and increases the air pressure within.
    • Air is forced out of the lungs.

• External Respiration: Exchange of gases between the lungs and the blood.

• Internal Respiration: Exchange of gases between the blood and body tissues/cells

• Cellular Respiration: ATP production within cells:

  • The formula for cellular respiration is: C6H12O6 + O2 → CO2 + H2O + ATP

Breathing: Inhalation and Exhalation

• Inhalation:

  • Increased levels of CO2 and H+ trigger the breathing center in the brain.
  • The medulla oblongata sends nerve impulses.
  • The rib muscles contract raising the rib cage.
  • The diaphragm contracts, moving downward.
  • Chest cavity expands, air pressure drops.
  • Air rushes into the lungs.

• Exhalation:

  • Stretch receptors in the alveoli signal the medulla oblongata to stop signaling.
  • The rib cage/diaphragm relax.
  • Air pressure increases inside the chest cavity.
  • Air is forced out of the lungs.

Negative Pressure

• Breathing is driven by negative pressure in the lungs.

• The lungs do not actively push air out. Instead, the lower air pressure inside the lungs draws air in.

Additional Receptors

• Carotid bodies: Located in the carotid artery.
• Aortic bodies: Located in the aorta.
• These receptors respond to high hydrogen ion concentration and high carbon dioxide levels in the blood, impacting breathing rates.

Gas Exchange: General Rules

• External Respiration:
  • High O2 concentration in the alveoli facilitates diffusion into the bloodstream.
  • Oxygen binds to hemoglobin forming oxyhemoglobin.
• Carbon Dioxide Removal:
  • CO2 diffuses from the tissues into the blood.
  • Some CO2 dissolves in the blood, and the rest reacts with water, forming bicarbonate ions.
  • Bicarbonate ions help transport the CO2 to the lungs.
  • CO2 is released from the body during exhalation.

Internal Respiration

• Blood to Tissues:

  • CO2 diffuses from the tissues into the blood stream
  • Hemoglobin picks up CO2, to form carbaminohemoglobin.
  • 64% of CO2 reacts with water via carbonic anhydrase to form bicarbonate (HCO3-) and hydrogen ions (H+).
  • This releases O2 into the tissues.

• The blood leaving the tissues now carries substantial amounts of carbaminohemoglobin as well as reduced hemoglobin.

Explore the essential functions of the respiratory system and its critical role in oxygen delivery and carbon dioxide removal. This quiz covers the basic processes of breathing, as well as the intricacies of external and internal respiration. Test your knowledge about how the respiratory and circulatory systems work together for human survival.