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Volumes and Capacities of the Pulmonary System

Respiratory volume are as follows:


(I) Tidal volume (TV)

It’s simply referred to as regular breathing when no force or pressure is applied.

This is the amount of air that is frequently breathed or expelled in a single breath without expending extra effort or the volume of air that is normally inspired or expired.

For instance, as you read this great post, you are involuntarily inhaling and exhaling air without exerting any force. Another time is when you’re asleep.


It’s 500 ml in a healthy adult, 15 ml in newborns, and 0 ml in foetuses.


(ii) Inspiratory reserve volume (IRV): 

After tidal volume has happened, this is the additional air forced by inspiration.

For example, after finishing a 100-meter race, you tend to forcibly inhale air (more like taking a deep breath) into your lungs, inhaling more than 500ml of the normal tidal volume that most adults do.

IRV stands for excess inhaled air and ranges from 2500 to 3100 ml.


(iii) Expiratory reserve volume (ERV)

In addition to the 500 ml of air inhaled, one can push out 1100 ml of air.

Expiratory reserve volume refers to the additional air that can be exhaled through voluntary or involuntary application of pressure.

For example, one might exhale more than 500ml of normal Tidal volume of air to apply pressure to his or her clogged nose, which is interfering with normal breathing (tidal volume) Note that in circumstances like cardiac arrest or heart attack, this might happen involuntarily. (1000–1100 mL, with forcible expiration providing more air).


(iv) Reserve volume (RV)

Having forcefully exhaled air ( Expiratory reserve volume) which definitely will exceed 500ml, the total amount of air Reserved in the lungs is known as RESERVE VOLUME/RESIDUAL VOLUME. 

After a vigorous expiration, there is still a significant amount of air in the lungs. Spirometry cannot be used to determine this.

Furthermore, after violent expiration, approximately 1100 to 1200 ml of air remains in the lungs.

The following are the respiratory capacities:

(i) Total Lung capacity (TLC)

In order to figure out how much air you can take in, you’ll need to know your overall lung capacity.

Except for Reserve Volume (RV), which must be known and measured using a spirometer, all four lung volumes must be known and measured using a spirometer.


If the Tidal Volume (TV) is 500ml, the Inspiratory Reserved Volume should be the average of 2500-3100, as previously indicated, leaving us with 2800, with Expiratory Reserved Volume being 1100 and Reserved Volume being about 1200.

As a result, TLC equals TV + IRV + ERV + RV.

500+2800+1100+1200= 5600 TLC

The total lung capacity (TLC) is then estimated to be around 5600~5800.

(ii) Inspiratory Capacity (IC), i.e. TV + IRV

The outcome of combining inspiratory reserve volume with tidal volume is the result (IC).

It’s the entire amount of air a person can inhale with his lungs stretched to their greatest capacity.

The volume of I.C is said to be between 3300 and 3500ml.

(iii) Expiratory Capacity (EC), i.e. TV + ERV 

The sum of the Expiratory reserve volume and tidal volume results is the total volume (EC).

E.C is said to range between 1600 to 1800 ml.

(iv) Functional residual capacity (FRC):

Simply add the Expiratory reserve volume (ERV) to the Reserved volume (RV) to get the functional residual capacity (ERV + RV).

It’s simply the amount of air left in the lungs after normal expiration, which is estimated to be around 2300ml.

(v) Vital capacity (VC):

Simply add the Expiratory Reserve Volume to the Inspiratory Reserve Volume to the Tidal Volume (IRV + ERV + TV) to determine this.

It’s also the greatest amount of air that may be inhaled or exhaled after forced expiration or inspiration, which is around 4400-4600ml.

Ans204 functions of macronutrients


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