The key difference between perfusion and ventilation is that perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or tissue, while ventilation is the flow of air between the environment and the lungs via inhalation and exhalation.
Perfusion and ventilation are very important phenomena for body organs such as the lungs and heart. One of the primary functions of the lungs is to facilitate gas exchange between the circulatory system and the outer environment. The gas exchange typically starts in the lungs between alveolar air and the blood of the pulmonary capillaries in the lungs. Therefore, the alveoli should be properly ventilated and perfused for an effective functional gas exchange. Thus, perfusion and ventilation are essential phenomena in gas exchange in the lungs and respiration. Moreover, changes in perfusion and ventilation can lead to medical conditions such as hypoxemia.
CONTENTS
1. Overview and Key Difference
2. What is Perfusion
3. What is Ventilation
4. Similarities – Perfusion and Ventilation
5. Perfusion vs Ventilation in Tabular Form
6. Summary – Perfusion vs Ventilation
What is Perfusion?
Perfusion refers to the delivery of blood to a capillary bed in tissues of organs. It is usually measured as the rate at which blood is delivered to the tissue. The SI unit of perfusion is m3/(s·kg). However, human organ perfusion is measured in ml/min/g. In 1920, a scientist named August Krogh first described this phenomenon. He was later awarded the Nobel Prize in Physiology or Medicine for his work. Krogh described the adaptation of blood perfusion in muscles and other organs based on demand.
Figure 01: Perfusion
Poor perfusion is called ischemia. Ischemia causes health problems such as coronary artery disease, cerebrovascular disease, peripheral artery disease, and many other conditions. Furthermore, in medical setups, the symbol Q represents perfusion when referring to cardiac output.
What is Ventilation?
Ventilation (V) is the flow of air into and out of the alveoli. In medicine, ventilation is the process of the lungs gaining air by exchanging its contents with the external environment. This is known as pulmonary ventilation. Pulmonary ventilation is the process that allows people to breathe physically. Pulmonary ventilation usually involves the respiratory system, including the nose, mouth, lungs, diaphragm, and respiratory passages like bronchus and bronchiole. Moreover, a person at rest generally breathes and exhales air at a rate of five to six liters per minute.
Figure 02: Ventilation
There is another type of ventilation which is referred to as mechanical ventilation. Sometimes, people need assistance with mechanical ventilation. Mechanical ventilation is the process by which the gas exchange between the lungs and the air occurs through the assistance of an external device connected to a patient.
What are the Similarities Between Perfusion and Ventilation?
- Perfusion and ventilation are very important phenomena for body organs like the lungs and heart.
- In fact, perfusion and ventilation are two associated processes.
- They are specifically essential phenomena in gas exchange in the lungs and respiration.
- Changes in perfusion and ventilation lead to medical conditions such as hypoxemia and cardiovascular diseases.
What is the Difference Between Perfusion and Ventilation?
Perfusion is defined as the passage of fluid through the circulatory system or lymphatic system to an organ or tissue, while ventilation is defined as the flow of air between the environment and the lungs via inhalation and exhalation. Thus, this is the key difference between perfusion and ventilation. Furthermore, perfusion occurs in the body’s organs, such as the heart, lungs, brain, kidneys, etc. On the other hand, ventilation mainly occurs in the lungs.
The infographic below presents the differences between perfusion and ventilation in tabular form for side-by-side comparison.
Summary – Perfusion vs Ventilation
Perfusion and ventilation are two associated phenomena that are critical processes for body organs such as the lungs, heart, brain, and kidney. Perfusion refers to the delivery of blood to a capillary bed in tissues of organs, while ventilation refers to the air movement between the environment and the lungs via inhalation and exhalation. Perfusion commonly occurs in organs like the heart, lungs, brain, kidneys, etc. On the other hand, ventilation mainly occurs in the lungs. So, this summarizes the difference between perfusion and ventilation.
Reference:
1. “Perfusion – an Overview.” ScienceDirect Topics.
2. “Pulmonary Ventilation and Perfusion.” – Statpearls – NCBI.
Image Courtesy:
1. “Perfusion Diagram” By J dotter – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Biology of ventilation” By Eleanor Lutz – Tabletop Whale: Explaining ventilators for COVID-19 (CC0) via Commons Wikimedia