Both inhalation and exhalation are two significant components of the respiratory system. The respiratory system is a cluster of organs that are involved in the exchange of oxygen and carbon dioxide within the body. These two processes strictly follow Boyle’s Law that states pressure and volume are inversely proportional; likewise, these two parts of respiration rely on the pressure between the lungs and atmosphere. Along with that thoracic cavity plays a significant role in breathing.
However, the inhalation and exhalation processes are different from each other. Nonetheless, both of them are dependent on each other in completing a full circle of respiration.
It is only through inhalation and exhalation that your body brings in oxygen and expels carbon dioxide. This process is facilitated by a large dome-shaped muscle under your lungs called the diaphragm.
A healthy adult takes typically 12-18 breaths per minute. While an inhalation takes two seconds, an exhalation requires three seconds on average.
Meaning of Inhalation
Inhalation definition refers to the process of breathing in air, containing oxygen and transporting it to the lungs. It is the first segment of respiration and is known as an active process. During inhalation, the diaphragm and intercostal muscle contract, which results in the expansion of lung volume. Simultaneously, the thoracic cavity expands, creating a difference in pressure between the atmosphere and the alveolus and allowing air to enter the lungs.
It is an autonomic process that does not require any conscious control or effort but can be (within limits) consciously controlled or interrupted.
Once you get an idea of what inhalation is now, it’s time to learn about exhalation.
Meaning of Exhalation
Similarly, exhalation is the process of releasing air containing carbon dioxide out of the lungs. It is the concluding part of respiration and is referred to as passive action. During exhalation, the diaphragm relaxes and moves towards the thoracic cavity. This occurs due to the elastic properties of the lungs and the internal intercostal muscles, which lowers the ribcage and decreases thoracic volume. In this process, the pressure within the thoracic cavity increases and allows the airflow out of the lungs.
When forced exhalation occurs (ex-blowing out a candle), expiratory muscles, such as the abdominal and internal intercostal muscles, produce abdominal and thoracic pressure, forcing air out of the lungs.
The inhalation and exhalation processes are spontaneous events that do not require any conscious effort.
However, just like inhalation can be controlled within limits, we can also break down the conscious control of your exhalation into two categories of, voluntary control and involuntary control.
Air is held in the lungs and slowly released at a fixed rate during voluntary exhalation.
Ex - singing, playing an instrument, exercising.
Dissimilarities Between Inhalation and Exhalation
The following table contains the striking differences between the inhalation and exhalation processes.
Mechanism of Inhalation and Exhalation
The lung is the primary organ that actively takes part in respiration. However, several other supporting muscles and organs aid in carrying out the inhalation and exhalation process.
Both Inhalation and Exhalation occur due to Pressure Gradients.
During Inhalation, the lung volume increases. According to Boyle’s law, lung pressure reduces compared to atmospheric pressure. It makes the air rush into lungs. Afterwards, blood promptly transports the air containing oxygen to every part of the body.
The process of inhalation starts when we inhale air through our nose or our mouth. From there, it travels down through your windpipe which is divided into airways called bronchial tubes. These airways always need to be open and free of any inflammation or mucus for our lungs to perform their best.
The air flows through bronchial tubes into our lungs, dividing into several smaller airways called bronchioles. These bronchioles divide into even smaller balloon-like structures called alveoli. Our body contains about 600 million alveoli.
Tiny blood vessels, called capillaries, form a mesh around the alveoli. It is at this stage that the oxygen that was previously inhaled is filtered and passed into your blood.
After absorbing the oxygen, the blood then goes to our heart. The heart pumps the blood all through our body to the cells and organs.
The cells and organs absorb the oxygen, producing carbon dioxide which goes back into the blood.
In the case of expiration, the lung volume decreases because of the elastic flinch of lung tissues. As a result, the pressure within the lungs increases compared to the outside pressure. It allows the air carrying carbon dioxide to push out of the body.
Diffusion in the alveoli allows for the exchange of O2 into the pulmonary capillaries as well as the removal of CO2 and other gases to be exhaled. The diaphragm relaxes for the lungs to release air, pushing up on the lungs. The air then passes via the trachea, larynx, and pharynx before exiting the body through the nasal cavity and mouth cavity.
The tiny sacs within the lungs or alveoli also play a crucial role in respiration.
During inspiration, alveoli help in exchanging oxygen with bloodstreams. On the other hand, during expiration, take out carbon dioxide from the blood.
Fill in the Gap: Aerobic respiratory passage is also known as ____________ pathway.
Gaseous Components During Inspiration and Expiration
Did You Know?
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