Lecture Notes: Gas Exchange

Introduction

Presenter: Armando Hassuran
Focus: Mechanism of gas exchange (oxygen and carbon dioxide) in the body
Purpose: Understanding how gases are transported to and from different parts of the body

Deoxygenated Blood:
- Returns to the heart after tissue use
- Contains low oxygen, high carbon dioxide
- Travels from tissues via venules and veins
- Enters the heart through the inferior or superior vena cava
Pulmonary Circulation:
- Deoxygenated blood is pumped from the heart to the lungs via the pulmonary artery
- Blood offloads carbon dioxide in the lungs
- Blood is reoxygenated, gaining more oxygen
- Oxygenated blood returns to the heart via the pulmonary vein
Systemic Circulation:
- Oxygenated blood is pumped to the body through the aorta
- Travels through arteries, arterioles, then capillaries to tissues
- Oxygen is offloaded to tissues, carbon dioxide is absorbed

Oxygen:
- Dissolved in plasma
- Mostly transported bound to hemoglobin (Hb)
Carbon Dioxide:
- Small amount dissolved in plasma
- Reacts with water, forms bicarbonate and hydrogen ions
- Majority transported as bicarbonate in plasma
- Also transported as carbaminohemoglobin in red blood cells

Alveoli:
- Gas exchange site within the lungs
- Blood supply from the pulmonary artery and vein
Process:
- Carbon dioxide transported back to alveoli and exhaled
- Oxygen inhaled into alveoli, diffuses into blood

Oxygen:
- 98% transported bound to hemoglobin
- Less than 2% dissolved in plasma
Carbon Dioxide:
- 10% dissolved in plasma
- 20% as carbaminohemoglobin
- 70% as bicarbonate