Internal and external respiration are two critical processes involved in the overall respiratory system, facilitating gas exchange in the body. Here’s a detailed explanation of each:
External Respiration
Definition:
External respiration refers to the exchange of gases between the external environment and the lungs, specifically occurring in the alveoli of the lungs. This process involves the movement of oxygen from the air into the blood and carbon dioxide from the blood into the air.
Process:
- Ventilation (Breathing):
- Inhalation: Air is drawn into the lungs due to the negative pressure created by the diaphragm and intercostal muscles. This air contains a high concentration of oxygen.
- Exhalation: Air is expelled from the lungs due to the relaxation of the diaphragm and intercostal muscles, removing carbon dioxide from the body.
2. Gas Exchange in Alveoli:
- Oxygen in the inhaled air diffuses across the thin walls of the alveoli into the surrounding pulmonary capillaries where it binds to hemoglobin in red blood cells.
- Carbon dioxide, a waste product of cellular metabolism, diffuses from the blood in the pulmonary capillaries into the alveoli to be exhaled.
Mechanism:
- The diffusion of gases is driven by concentration gradients: oxygen moves from areas of higher concentration (alveoli) to lower concentration (blood), and carbon dioxide moves from higher concentration (blood) to lower concentration (alveoli).
Importance:
- This process is essential for oxygenating the blood, which will then deliver oxygen to tissues throughout the body, and for removing carbon dioxide, a metabolic waste product.
Internal Respiration
Definition:
Internal respiration refers to the exchange of gases between the blood and the body’s cells. This process occurs in the systemic capillaries where oxygen diffuses from the blood into the tissues, and carbon dioxide diffuses from the tissues into the blood.
Process:
- Oxygen Transport to Tissues:
- Oxygen-rich blood is transported from the lungs to the heart, which then pumps it through systemic arteries to tissues throughout the body.
- Oxygen diffuses from the blood in the systemic capillaries into the cells of tissues where it is used for cellular respiration (production of ATP).
2. Carbon Dioxide Removal from Tissues:
- Carbon dioxide, produced as a byproduct of cellular respiration, diffuses from the cells into the blood in the systemic capillaries.
- The blood, now carrying carbon dioxide, returns to the heart via systemic veins and is then pumped to the lungs for removal through external respiration.
Mechanism:
- Similar to external respiration, the diffusion of gases in internal respiration is driven by concentration gradients: oxygen moves from higher concentration (blood) to lower concentration (tissues), and carbon dioxide moves from higher concentration (tissues) to lower concentration (blood).
Importance:
- This process is vital for supplying oxygen to cells for energy production and for removing carbon dioxide, which, if accumulated, can lead to acid-base imbalances in the body.
Summary of Differences
- Location:
- External Respiration: Occurs in the lungs (alveoli and pulmonary capillaries).
- Internal Respiration: Occurs in the tissues throughout the body (systemic capillaries and body cells).
- Primary Function:
- External Respiration: Gas exchange between the environment and blood.
- Internal Respiration: Gas exchange between the blood and the body’s cells.
- Gases Involved:
- External Respiration: Oxygen from the air to blood, carbon dioxide from the blood to the air.
- Internal Respiration: Oxygen from blood to cells, carbon dioxide from cells to blood.
Understanding these two types of respiration is fundamental for comprehending how the respiratory system supports cellular function and overall homeostasis in the body.