Lecture on the Human Respiratory System

Introduction

• The human respiratory system facilitates the exchange of gases: oxygen intake and carbon dioxide expulsion.
• Don't confuse the respiratory system with cellular respiration.
  • Cellular respiration uses oxygen to make ATP and produces carbon dioxide as a byproduct.

Pathway of Air

1. Nasal Cavity
   • Air is warmed, humidified, and filtered by mucus and hairs (nasal hairs and microscopic cilia).
2. Pharynx
   • A junction for both food and air.
3. Larynx (Voice Box)
4. Trachea
   • A tube supported by rings of cartilage.
   • Food is meant to travel down the esophagus, not the trachea.
5. Bronchial Tree
   • Primary bronchi (one for each lung) -> Secondary bronchi -> Tertiary bronchi -> Smaller bronchioles.
   • Resembles an upside-down tree.

Lungs

• Two lungs: right lung has 3 lobes, left lung has 2 lobes.
• Left lung has a cardiac notch for the heart.

Gas Exchange

• Occurs in alveoli within alveolar sacs (similar to a bunch of grapes).
• Alveoli are thin-walled, have a large surface area, and are in contact with capillaries.
  • Red blood cells pick up oxygen and deliver carbon dioxide to be expelled.

Interaction with Other Systems

• Circulatory System: Works closely with the respiratory system for gas exchange.
• Skeletal System: Ribs protect the lungs.
• Muscular System: Involves the diaphragm, intercostal muscles, and abdominal muscles to aid breathing.

Regulation of Breathing

• Mostly involuntary, regulated by the nervous system using blood pH as a measure.
• Increase in blood carbon dioxide raises H+ concentration, lowering pH (more acidic).
• Brain adjusts breath rate and depth to maintain homeostasis.

Other Notes

• Gas exchange methods vary in other organisms (e.g., earthworms through skin, fish via gills).
• Respiratory system’s understanding aids in treating conditions like asthma or respiratory distress syndrome (RDS).
  • Premature infants may lack surfactant, causing alveolar collapse, treatable with artificial surfactants.

Careers

• Pulmonologists and respiratory therapists focus on respiratory health and treatment.

Conclusion

• Understanding the respiratory system is crucial for medical advancements and treatment of related illnesses.
• Encouragement to stay curious about how the body functions.