External Respiration vs. Internal Respiration

Attribute	External Respiration	Internal Respiration
Definition	The exchange of gases (oxygen and carbon dioxide) between the external environment and the lungs.	The exchange of gases (oxygen and carbon dioxide) between the blood and the body tissues.
Location	Takes place in the lungs.	Takes place in the body tissues.
Process	Involves inhalation and exhalation.	Involves cellular respiration.
Gas Exchange	Oxygen is taken in from the environment, and carbon dioxide is released to the environment.	Oxygen is released from the blood to the tissues, and carbon dioxide is taken in from the tissues to the blood.
Transport Medium	Air (inhaled and exhaled).	Blood.
Respiratory Surface	Alveoli in the lungs.	Cell membranes in the body tissues.
Gas Concentration	Higher oxygen concentration in the environment, lower oxygen concentration in the blood. Higher carbon dioxide concentration in the blood, lower carbon dioxide concentration in the environment.	Higher oxygen concentration in the blood, lower oxygen concentration in the tissues. Higher carbon dioxide concentration in the tissues, lower carbon dioxide concentration in the blood.

Introduction

Respiration is a vital process that allows living organisms to exchange gases with their environment. In humans, respiration can be divided into two main processes: external respiration and internal respiration. While both processes are essential for the survival of the body, they occur in different locations and serve distinct functions. In this article, we will explore the attributes of external respiration and internal respiration, highlighting their differences and importance.

External Respiration

External respiration, also known as pulmonary respiration, refers to the exchange of gases between the external environment and the lungs. This process involves the inhalation of oxygen-rich air and the exhalation of carbon dioxide. The primary site of external respiration is the alveoli, tiny air sacs located at the end of the bronchial tree within the lungs.

During external respiration, oxygen from the inhaled air diffuses across the thin walls of the alveoli into the surrounding capillaries. Simultaneously, carbon dioxide, a waste product of cellular metabolism, diffuses from the capillaries into the alveoli to be expelled during exhalation. This exchange of gases is facilitated by the high surface area and thinness of the alveolar walls, allowing for efficient diffusion.

External respiration is driven by the pressure gradient between the alveoli and the blood vessels. Oxygen, being at a higher concentration in the alveoli, moves from an area of high pressure to an area of low pressure in the capillaries. Conversely, carbon dioxide, which is at a higher concentration in the blood, moves from the capillaries to the alveoli where its concentration is lower. This process ensures the continuous supply of oxygen to the body and the removal of carbon dioxide, maintaining proper gas exchange.

Furthermore, external respiration is influenced by various factors such as the partial pressure of gases, the surface area available for diffusion, and the thickness of the respiratory membrane. Any disruption in these factors can impair the efficiency of external respiration and lead to respiratory disorders.

Internal Respiration

Internal respiration, also known as tissue respiration, refers to the exchange of gases between the blood and the body's cells. Unlike external respiration, which occurs in the lungs, internal respiration takes place in the systemic capillaries throughout the body. This process involves the delivery of oxygen-rich blood to the tissues and the removal of carbon dioxide produced by cellular metabolism.

During internal respiration, oxygenated blood from the lungs is transported by the circulatory system to the body's tissues. Within the capillaries, oxygen diffuses from the blood into the interstitial fluid and then into the cells, where it is utilized in cellular respiration to produce energy. At the same time, carbon dioxide, a byproduct of cellular respiration, diffuses out of the cells into the interstitial fluid and then into the capillaries to be transported back to the lungs for elimination.

Internal respiration is driven by the concentration gradient of gases between the blood and the cells. Oxygen, being at a higher concentration in the blood, moves from the capillaries into the cells where its concentration is lower. Conversely, carbon dioxide, which is at a higher concentration in the cells, moves from the cells into the capillaries where its concentration is lower. This exchange of gases ensures that the cells receive the necessary oxygen for their metabolic activities and that waste carbon dioxide is efficiently removed.

Similar to external respiration, internal respiration is influenced by factors such as the partial pressure of gases, the surface area available for diffusion, and the distance between the capillaries and the cells. Any disruption in these factors can hinder the exchange of gases and compromise cellular function.

Comparison

While external respiration and internal respiration are distinct processes, they are interconnected and essential for the overall functioning of the respiratory system. Here are some key attributes that differentiate the two:

Location

External respiration occurs in the lungs, specifically in the alveoli, where the exchange of gases between the external environment and the body takes place. On the other hand, internal respiration occurs in the systemic capillaries throughout the body, where the exchange of gases between the blood and the cells occurs.

Function

The primary function of external respiration is to supply oxygen to the body and remove carbon dioxide. It ensures the continuous exchange of gases between the lungs and the external environment. In contrast, the main function of internal respiration is to deliver oxygen to the cells and remove carbon dioxide produced by cellular metabolism. It ensures the exchange of gases between the blood and the body's tissues.

Driving Force

External respiration is driven by the pressure gradient between the alveoli and the blood vessels. Oxygen moves from an area of high pressure in the alveoli to an area of low pressure in the capillaries, while carbon dioxide moves in the opposite direction. On the other hand, internal respiration is driven by the concentration gradient of gases between the blood and the cells. Oxygen moves from an area of high concentration in the blood to an area of low concentration in the cells, while carbon dioxide moves in the opposite direction.

Gas Exchange Site

The site of gas exchange in external respiration is the alveoli, where oxygen diffuses into the blood and carbon dioxide diffuses out of the blood. In internal respiration, the site of gas exchange is the systemic capillaries, where oxygen diffuses from the blood into the cells and carbon dioxide diffuses from the cells into the blood.

Factors Influencing Respiration

Both external and internal respiration are influenced by factors such as the partial pressure of gases, the surface area available for diffusion, and the distance over which diffusion occurs. However, the specific factors affecting each process may vary. For example, in external respiration, the surface area and thickness of the alveolar walls play a crucial role, while in internal respiration, the distance between the capillaries and the cells is a significant factor.

Conclusion

In conclusion, external respiration and internal respiration are two essential processes involved in the exchange of gases within the human body. External respiration occurs in the lungs and facilitates the exchange of gases between the alveoli and the blood, while internal respiration occurs in the systemic capillaries and enables the exchange of gases between the blood and the body's cells. Both processes are driven by different mechanisms and influenced by various factors. Understanding the attributes and significance of external and internal respiration is crucial for comprehending the respiratory system's functioning and its role in maintaining homeostasis.