Breathing and Exchange of Gases NEET Notes

Complete Breathing and Exchange of Gases Notes for Class 11 Biology | NEET Revision and NCERT Solutions

Every living cell requires continuous expenditure of energy for various life processes like growth, development and multiplication. This energy is derived from the oxidation of organic compounds. The biological oxidation of these compounds constitutes the process of respiration. Respiration is thus defined as, “the biochemical oxidation of organic compounds like glucose to yield energy”.

ORGANS FOR RESPIRATORY EXCHANGE IN VARIOUS ANIMALS

In simple animals like Amoeba, Paramecium, the body organization is very simple, so gases can diffuse in and out from the general surface of the body. The air diffuses across the membrane from the side where its partial pressure is more to the side where its partial pressure is less. However, there are no special organs of respiration.
There are no special organs for respiration in Hydra as the body organisation is very simple and the cells are directly exposed to the environment. Dissolved oxygen enters the cells of Hydra through the general body surface, as there is less oxygen concentration within the cells. Carbon dioxide produced after respiration also comes out in a similar way. This process is termed as diffusion.
There are no special respiratory organs in earthworms and leeches but the exchange of gases occurs through the skin (cutaneous respiration). The skin is always kept moist by the secretions of mucous glands, and is richly supplied with blood capillaries. Oxygen from the atmosphere dissolves into mucous and diffuses in. It is then transported to the body tissues by hemoglobin of the blood. In them, hemoglobin is dissolved in plasma and not present in the corpuscles unlike other animals.
In insects, gas exchange occurs through tracheal system because in them the integument has become impermeable to gases to reduce the water loss. Trachea are fine tubes that open to the outside by spiracles. Each trachea branches into tracheoles that again branch extensively in the tissues and finally end into air sacs.
Inspiration and expiration occur through the spiracles. When the abdominal muscles relax, the air is drawn into the spiracles, trachea and tracheoles. This then diffuses through the body fluids to reach the cells. When the abdominal muscles contract, the air is driven out through the tracheal system via the spiracles. Thus, in insect’s expiration is an active process but inspiration is passive. In the marine annelid Nereis respiration occurs by the whole-body surface, but more specially by thin, flattened lobes of parapodia, which possess extensive capillary network.
They are richly supplied with blood capillaries and are highly permeable to respiratory gases.
Aquatic animals like prawns, fishes and tadpoles (of frog) respire with the help of gills. Gills are richly supplied with blood and can readily absorb oxygen dissolved in water. The surface of the gills is increased by the presence of gill plates. Each gill plate has many flat and parallel membranes like gill lamellae. Water moves over these gills in single direction only. The oxygen absorbed by the gills from the water is taken by blood and carbon dioxide is given out into the water.
In amphibians like frogs and toads, some cutaneous respiration takes place across their moist and highly vascular skin, particularly during hibernation. However, they mainly respire through the lungs and the moist mucus membrane of the buccal cavity. Toads have less of cutaneous respiration than frogs.

HUMAN RESPIRATORY SYSTEM

All mammals have lungs for respiration. This is known as pulmonary respiration. The mammalian respiratory system consists of the nasal cavity, naso-pharynx, larynx, trachea, bronchi, bronchioles and lungs.
Nasal cavity: It is a large cavity lying dorsal to the mouth and is lined by mucous secreting epithelium. The nasal cavity opens outside through a pair of external nostrils or nares. Bones and cartilages support the nasal cavity. The nasal cavity is divided into two parts by a nasal septum. The cavity opens inside into pharynx through two internal nostrils. Air while passing through the nasal cavity is filtered, and only the clean air free from dust particles and foreign substances enters the pharynx. The air also gets warmed and moistened in this chamber. It is important to note that air can also be inhaled through mouth directly, but this is not advisable because the air will not be filtered, warmed and moistened. This gradually will harm the respiratory system.

Nasopharynx: It is a chamber situated behind the nasal cavity. At the level of soft palate, it becomes continuous with the mouth cavity or oral pharynx. It also receives the openings of eustachian tubes on its lateral sides and is thus connected to the middle ear.

Larynx: It is the chamber situated in the region of the neck. It is supported by four cartilages: thyroid is the largest and is in the form of a broad ring incomplete dorsally, cricoid is a complete ring lying at the base of the thyroid, a pair of arytenoids lying above the thyroids but in front of cricoid, and epiglottis situated behind the tongue that serves to cover the entrance to the trachea so that the food particles may not enter it. Larynx is also known as voice box since it helps in the production of sound.

Trachea: It is the tube starting from larynx running through the neck and the thoracic cavity. The trachea runs through the neck in front of the oesophagus. The trachea or windpipe is about 12 cm long and divided into two bronchi in the thoracic region.

Bronchi and Bronchioles: The two bronchi enter into right and left lungs on either side. Inside the lungs, they further branch into many small bronchioles with a diameter of about 1mm. These bronchioles further divide into terminal and then into respiratory bronchioles. Each respiratory bronchiole divides into a number of alveolar ducts that further divide into atria, which swell up into air sacs or alveoli.

Lungs: a pair of conical shaped lungs is situated in the double walled sacs called pleural cavities. The are spongy and richly supplied with blood vessels and capillaries. They have about 300-400 millions of alveoli through which exchange of gases takes place. Lungs have various bronchioles ending into alveoli where exchange of gases takes place. The alveoli are thin walled pouches the walls of which have epithelial linings supported by basement membranes.

MECHANISM OF BREATHING OR PULMONARY RESPIRATION

Respiration involves the following steps:

Breathing or pulmonary ventilation by which atmospheric air is drawn in and Carbon dioxide air released out.
Diffusion of gases of oxygen and carbon dioxide across alveolar membrane.
Transport of gases by the blood.
Diffusion of oxygen and carbon dioxide between blood and tissues.
Utilization of oxygen by the cells for catabolic reactions and release of carbon dioxide.

Mechanism of Breathing:

Inspiration: During this process, some intercostal muscles contract thus pulling the ribs upwards and outwards. Lateral thoracic walls also move outwards and upwards. At the same time the diaphragm becomes flattened as it moves down towards the and men. This results in the increase in the volume of thoracic cavity thus lowering the pressure in the lungs. To fill up this gap, air from outside rushes in to bring about inhalation or inspiration. Hence, inspiration is brought about by contraction of the diaphragm and some intercostal muscles; these muscles are known as inspiratory muscles.

Expiration: During this process, the ribs return to their original position, inwards and backwards, by the relaxation of inter costal muscles and also the diaphragm becomes dome-shaped again. Lateral thoracic walls also move inwards and downwards. This decreases the volume of the thoracic cavity thus increasing the pressure inside the lungs. So, the air from the lungs rushes out through the respiratory passage bringing about expiration or exhalation.

A person breathes about 12 to 16 times per minute while at rest. However, this breathing rate is higher at the time of muscular exercise and in small children.
In forceful expiration, different group of intercostal muscles and some abdominal muscles contract to reduce the volume of the thorax more than that in ordinary expiration. So, more air is expelled out. Such muscles are known as expiratory muscles.

PULMONARY AIR VOLUMES

Air flows into and out of the lungs because of the pressure gradient. Spirometer is an instrument used to measure the amount of air exchanged during breathing. Some terms regarding pulmonary air volumes re as follows:
Tidal volume: It is the volume of air that is breathed in and breathed out while sitting at rest (effortless respiration) or “quiet breathing”. It is about 500 ml in an adult person.
Vital capacity: It is the volume of air that can be maximum expelled out after a maximum inspiratory effort. It is about 4,500 ml in males; and 3,000 ml in females. The higher the vital capacity, the greater will be the capacity for increasing the ventilation of lungs for exchange of gases. It is more in athletes and mountain dwellers.
Residual volume: It is the volume of air that remains inside the lungs and respiratory passage (about 1.5 liters) after a maximum forced exhalation.
Inspiratory reserve volume (IRV): It is the volume of air that can be taken in by forced inspiration over and above the normal inspiration or tidal volume. It is about 2,000 ml to 3,500 ml.
Expiratory reserve volume (ERV): It is the volume of air that can still be given out by forced expiration over and above the normal inspiration or tidal volume. It is about 1,000 ml.
Total lung capacity: It is the volume of air in the lungs and respiratory passage after a maximum inhalation effort. It is equivalent to vital capacity plus residual volume. It is about 5,000 to 6,000 ml in adult males.
Tidal volume (TV) Volume of air inspired or expired during a normal respiration (volume of air renewed in the respiratory system during each breathing). 500ml

PULMONARY EXCHANGE OF GASES

In most of higher animals including man, the air from outside reaches up to the alveoli of lungs in the process of breathing. This inspired air contains about 21 per cent oxygen, 0.04 per cent carbon dioxide, 78.6 per cent nitrogen and small amounts of other gases and atmospheric moisture. In this inspired air the partial pressure of oxygen (Po2) is 158 mm Hg; and that of carbon dioxide (Pco2) is 0.3 mm Hg. The lungs and alveoli also contain some air even after expiration. But this air has more of carbon dioxide and less of oxygen than the inspired air. So when this air mixes with the inspired air the partial pressure of oxygen in alveolar air now becomes 100 mm Hg and that of carbon dioxide becomes 40 mm Hg. However, the percentage of oxygen now becomes 13.1% and that of carbon dioxide 5.3%.
The pulmonary artery contains deoxygenated blood and this has Po2 much less (40 mm Hg) than that of alveolar Po2. So, oxygen from the alveolar air diffuses into the blood capillaries (oxygenation). This oxygenated blood is collected from alveoli of lungs by the pulmonary veins. It has Po2 of about 95 mm Hg and at this partial pressure, the oxygenated blood has 19.8 per cent oxygen. Further, the deoxygenated blood in the pulmonary artery has a Pco2 of 46 mm Hg and Pco2 of alveolar air is 40 mm Hg. So the blood while passing through the alveoli of lungs also unloads carbon dioxide. The pulmonary vein carrying oxygenated blood, thus, has carbon dioxide at the partial pressure of 40 mm Hg. At these partial pressures the carbon dioxide contents of the blood decreases from 52.7 per cent to 49 per cent.

GAS TRANSPORT IN BLOOD:

OXYGEN TRANSPORT

The hemoglobin pigment of blood mainly transports oxygen. From alveoli of lungs, oxygen can readily diffuse into erythrocytes and combines loosely with hemoglobin (Hb) to form a reversible compound oxyhemoglobin (HbO2). Combining of oxygen with hemoglobin to form oxyhemoglobin is a physical process. There is no change in the valency of iron atom; it is ferrous in oxyhemoglobin and in hemoglobin. This reaction, therefore, is an “oxygenation” process and not oxidation. When fully oxygenated, hemoglobin has about 97 per cent of oxygen. Hemoglobin is dark red in colour; whereas oxyhemoglobin is bright red in colour.
Inside the tissues, as the partial pressure of oxygen is less, oxyhemoglobin gets dissociated into oxygen and hemoglobin. Further, as Po2 is much lower and Pco2 is much higher in active tissues than in passive tissues, so much of oxygen is released from oxyhemoglobin in active tissues. High tension of oxygen favors the formation of oxyhemoglobin while low tension of oxygen favours its dissociation. However, very little of oxygen is found in the blood plasma. Each decilitre of blood releases up to 4.6 ml, of oxygen in the tissues, 4.4 ml from oxyhemoglobin and 0.17 ml from the dissolved oxygen in the plasma.

Carbon Dioxide Transport:

Carbon dioxide is produced in the tissues as an product of tissue respiration. For its elimination, it gets dissolved in tissue fluid and passes into the blood. In the tissue, 100 ml of blood receives about 3.7 ml of carbon dioxide. It is transported both by the plasma and hemoglobin of blood. From the tissues, carbon dioxide diffuses into the blood plasma and forms carbonic acid (H2CO3-) in the presence of an enzyme carbon c anhydrase. Inside the erythrocytes, some of the carbonic acid forms bicarbonates and is thus transported. As carbonic acid, carbon dioxide is transported by blood plasma.

Carbonic anhydrase

CO2 + H2O > H2CO (carbonic acid)

H2CO3 > H+ + HCO3- (bicarbonate)

If all the carbon dioxide produced by the tissues is carried by blood plasma in this way, then pH of the blood will be lowered to about 4.5. This would immediately cause death. So only about 10% of the CO2 produced by the tissue is transported as carbonic acid.
About 20% of the total CO2 produced is transported by the hemoglobin of blood as carbaminohemoglobin.

CO2 + Hb.NH2 > Hb.NH.COOH

About 70 % of the total CO2 produced is transported as bicarbonate ions of the blood. Bicarbonates reformed both in the erythrocytes and in the plasma of blood.
In erythrocytes. CO2 from the plasma enters the erythrocytes and combines with water to form carbonic acid in the presence of the enzyme carbonic anhydrase. Carbonic acid soon dissociates to form H+ and HCO3- ions.

CO2 + H2O > H2CO3 > H+ + HCO3-

Hence, carbon dioxide is carried in the blood in three major forms; bicarbonates in plasma and erythrocytes, carbaminohemoglobin in erythrocytes, and small amounts of dissolved carbon dioxide in plasma.
On reaching the lungs, blood is oxygenated. Oxyhemoglobin is a stronger acid than deoxyhemoglobin. So, it donates H+ ion, which joins bicarbonate (HCO3-) to form carbonic acid and this carbonic acid is cleaved into water and carbon dioxide by an enzyme carbonic anhydrase. Oxygenation of hemoglobin releases carbon dioxide from carbaminohemoglobin. By this way, every decilitre of blood releases about 3.7 ml of carbon dioxide in the lungs. Then this carbon dioxide is removed from the lungs by exhalation.

GAS EXCHANGE IN TISSUES

In the tissues, gases are exchanged by diffusion (as in the lungs). In tissues, as the partial pressure of oxygen is very low (about 40 mm Hg), so the oxygen gets un loaded here. When the blood leaves the tissues, it has Po2 of 40 mm Hg. However, for carbon dioxide it is just the reverse. The blood entering tissues has Pco2 of 40 mm Hg; while Pco2 f tissues is 46 mm Hg. So, some of carbon dioxide from tissues gets loaded into the blood.

DISORDERS OF RESPIRATORY SYSTEM

Asthma: difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles.

Emphysema: alveolar walls are damaged due to which respiratory surface is decreased, causes of this is cigarette smoking.

Occupational Respiratory Disorders: long exposure to the dust of industries like stone breaking, etc. cause an inflammation on lung tissues and leads to lung damage.

NCERT Solutions

This chapter introduces the student to the concept of breathing and explains how it is different from respiration.

The focus is on the respiratory system and the organs that constitute the same. Exchange of gases like Oxygen and Carbondioxide and their transport is discussed in detail. The students also get a brief overview of repiratory problems, and the conditions that lead to them.

1. Define vital capacity. What is its significance?

Solution:

Vital capacity can be defined as the maximum volume of air a person can breathe in post a force expiration.

Significance of vital capacity:

It depicts the maximum amount of air that can be converted or renewed in the respiratory system in a single respiration
The excess quantity of inhaled air represents the maximum amount of oxygen available for glucose-oxidation. This way more energy is available for the body.

2. State the volume of air remaining in the lungs after a normal breathing.

Solution:

It can be stated by the functional residual capacity (FRC). FRC is the volume of air that remains in the lungs after a normal expiration. The functional residual capacity is both the expiratory reserve volume (ERV) and residual volume (RV).
The expiratory reserve volume is the maximum volume of air which can be exhaled post a normal expiration which is approximately1000ml-1500ml. The residual volume is the volume of air that remains in the lungs after maximum expiration which is about 1100ml to 1500ml.

Hence,

FRC = ERV + RV

≅ 1500 + 1500 = 3000 ml

Thus, the functional residual capacity of the lungs in human beings is nearly 2500 ml to 3000 ml

3. Diffusion of gases occurs in the alveolar region only and not in the other parts of

respiratory system. Why?

Solution:

Alveoli are the small air sacs of the lungs that allow rapid gas exchange. These structures are specially built for the gas exchange process. The thickness of the alveolar membrane in total is lesser than a millimeter, while the outer surface of the alveolar membrane is in close proximity with the linkage of blood capillaries.
The endothelial membrane of the blood capillaries and the alveolar membrane is distinguished by a fine basement substance. This fine barrier facilitates easy diffusion of the gases. The alveolar air that comes in close proximity with the blood capillaries has higer levels of pO2 and lower levels of pCO2 that promote the gas-diffusion. All these structural pluses that are found in alveoli is not present in any other structure of the respiratory system. Therefore, the gas diffusion phenomena occurs in the alveolar region only and not in any other part.

4.What are the major transport mechanisms for CO2? Explain.

Solution:

Carbon dioxide is liberated by a vigorously active tissue in the blood. On an average, every 100ml of blood accepts approximately 3.7ml of CO2 from tissues.

In blood, carbon dioxide is carried in three forms:

Carbon dioxide as a simple solution

Nearly 5-10% of carbon dioxide of the total volume of blood is dissolved in plasma and is transported as a simple physical solution

Carbon dioxide as a bicarbonate ion

The partial pressure of carbon dioxide at the tissue site is high due to catabolism. Carbon dioxide diffuses in the blood and forms carbonic acid after reacting with water. This reaction occurs in the presence of the carbonic anhydrase enzyme. The reaction is as follows:

Carbonic acid dissociates into H+ ions and bicarbonate. Some amount of bicarbonate ions is required to sustain the pH of blood. The hydrogen ions are used by the proteins, the remaining bicarbonate ions are picked up by the plasma.

Carbon dioxide as carbamino-haemoglobin

In tissues, when the partial pressure of oxygen is lower and the partial pressure of carbon dioxide is higher, the carbon dioxide loosely combines with the globin part of the reduced haemoglobin so as to form carbamino-haemoglobin. The reaction is as follows:

HbO2 + CO2 ⇌ HbCO3 + H+ + O2

Oxyhaemoglobin carbamino-haemoglobin

At the alveolar level, when pO2 is higher and the pCO2 is lower, the carbon dioxide dissociates from carbamino-haemoglobin. Therefore, carbon dioxide that is bound to haemoglobin is liberated in the alveoli.

5. What will be the pO2 and pCO2 in the atmospheric air compared to those in the alveolar air?

(i) pO2 lesser, pCO2 higher

(ii) pO2 higher, pCO2 lesser

(iii) pO2 higher, pCO2 higher

(iv) pO2 lesser, pCO2 lesser

Solution:

The pO2 and pCO2 in the atmospheric air compared to those in the alveolar air will be:

(ii) pO2 higher, pCO2 lesser

In a mixture of gases, each gas exerts a pressure known as partial pressure. These gases always diffuse across the pressure gradient. Oxygen permeates easily into the lungs when the level of pO2 is higher in the atmosphere. Likewise, carbon dioxide can diffuse out of the body easily if the pCO2 level is lower in the atmosphere.

6.Explain the process of inspiration under normal conditions.

Solution:

The process by which fresh air enters into the lungs is known as inspiration. When the intrapulmonary pressure (pressure in the lungs) is lesser than the atmospheric pressure, inspiration takes place. The muscles of the diaphragm, external intercostal muscles and abdominal muscles are referred to as the inspiratory muscles which bring about the process of inspiration.
The muscles of the diaphragm contract, pulling the diaphragm downwards to the abdominal cavity, causing it to become flat which results in an increase in the thoracic cavity in the antero-posterior direction. The contraction of the external intercostal muscles, lifts up the ribs and the sternum resulting in the expansion of the thoracic chamber, in a dorso-ventral orientation.
This overall increase in the thoracic volume increases the pulmonary volume which inturn causes the decrease of pressure in the lungs. The atmospheric pressure expels air from outwards into the lungs. To compress the abdominal organs, the abdominal muscles relax that causes an escalation in the strength of the inspiration. During inspiration, air takes the following passage:

7.How is respiration regulated?

Solution:

The medulla region of the brain having the respiratory rhythm center, is chiefly responsible for the regulation process of respiration. The function performed by the respiratory rhythm center can be altered by the pneumotaxic center through signals to reduce the inspiration rate. The chemo sensitive area located near the respiratory centre is sensitive to hydrogen ions and carbon dioxide. This are sends signals to alter the rate of expiration to eliminate compounds.
The levels of carbon dioxide and hydrogen ions in the blood is detected by the receptors located in the carotid artery and the aorta. As and when the carbon dioxide level increases, the respiratory centre sends across nerve impulses for the required changes.

8. What is the effect of pCO2 on oxygen transport?

Solution:

pCO2 has a crucial role to play in the process of oxygen transport. As a result of low pCO2 levels in the alveoli, oxygen tends to bind with the hemoglobin, to form Oxyhaemoglobin. Higher levels of pCO2 in the tissues promotes the dissociation of Oxyhaemoglobin. The level of pCO2 is low at the surface of the lungs, here O2 binds with the haemoglobin and dissociates at the tissue grade, where the level of pCO2 is higher.

9. What happens to the respiratory process in a man going up a hill?

Solution:

As we go up higher, the altitude increases. At this altitude, the concentration of atmospheric oxygen is lesser, which means to say that the partial pressure of oxygen declines. This situation of inadequate oxygen-supply, demands more of oxygen. In order to increase the supply of oxygen to the blood, the man begins to breathe rapidly. Therefore, it causes an increase in the heart rate to be able to meet the demand of oxygen supply.

10.What is the site of gaseous exchange in an insect?

Solution:

The respiratory organs of insects is trachea. Trachea has openings known as spiracles through which air enters. Spiracles are located on either side of the abdomen of the insect. A pair of spiracles are found on each segment of the abdomen. Furthermore, the trachea branches into smaller tubes until they reach the level of tissues. The oxygen that enters the trachea is exchanged by diffusion with the tissues. Simultaneously, carbon dioxide that reaches the trachea from the tissues is forced out of the body.

11.Define oxygen dissociation curve. Can you suggest any reason for its sigmoidal pattern?

Solution:

A graph attained when the percentage saturation of haemoglobin with oxygen is plotted against the partial pressure of oxygen.

The affinity of the second molecule of oxygen escalates when the first molecule of oxygen binds to haemoglobin. This is why the Oxyhaemoglobin formation is rapid and is represented by the steep slope of the S-curve as observed. When the formation of Oxyhaemoglobin comes to a halt, or when haemoglobin molecules are not available for binding, the curve attains a plateau phase.

12. Have you heard about hypoxia? Try to gather information about it, and discuss with your friends.

Solution:

Hypoxia is a pathological condition wherein the body on the whole or a part of the body is not supplied with sufficient oxygen.
Hypoxia is of different types, namely:
- Cytotoxic hypoxia – caused by cyanide poisoning
- Anaemic hypoxia – caused by deficiency of haemoglobin
- Hypoxic hypoxia – caused due to insufficient oxygen in the atmosphere
- Stagnant hypoxia – caused by reduced pumping activity of the heart or heart failure
- Carbon monoxide poisoning – Irreversible binding of CO to haemoglobin and the reduced oxygen transport.

Symptoms:

Shortness of breath
Rapid heart rate
Rapid breathing
Anxiousness
Lethargy
Difficulty in communicating
Confusion

Hypoxia is caused due to the following reasons:

The concentration of oxygen is low at higher altitudes which may lead to hypoxia
Hypoxia may also arise due to any of these respiratory disorders such as bronchitis, emphysema or asthma
Hypoxia can also be caused due to anaemia which is linked to a lesser number of red blood cells
It may arise due to heart problems such as tachycardia

13. Distinguish between

(a) IRV and ERV

(b) Inspiratory capacity and Expiratory capacity.

Solution:

The differences are as follows:

(a) IRV and ERV

IRV(Inspiratory reserve volume)

ERV(Expiratory reserve volume)

It is the volume of air that a person can additionally inspire through a compelled inspiration
It is the volume of air that a person can expire through an expelled expiration
For a healthy individual, the IRV is approximately 2500ml – 3000ml
For a healthy individual, the ERV is approximately 1000ml to 1100ml

(b) Inspiratory capacity and Expiratory capacity

Inspiratory capacity(IC)

Expiratory capacity(EC)

Inspiratory capacity is the volume of air that can be inhaled post a normal expiration
Expiratory capacity is the volume of air that be exhaled post a normal inspiration

It is given by the sum of tidal volume and the inspiratory reserve volume

i.e, IC = TV + IRV

It is given by the tidal volume and the expiratory reserve volume

i.e., EC = TV + ERV

Vital capacity(VC)

Total lung capacity(TLC)

After a maximum inspiration, it is the maximum volume of air that can be exhaled. It includes IC and ERV.
After maximum inspiration, it is the volume of air in the lungs. It includes ERV, IC and residual volume
The vital capacity in the lungs of humans is about 4000ml
The total lung capacity in the lungs of humans is nearly 5000ml to 6000ml

14. What is Tidal volume? Find out the Tidal volume (approximate value) for a healthy human in an hour.

Solution:

During a normal respiration, the volume of air expired or inspired is referred to as tidal volume(TV). The tidal volume is approximately 500ml for a healthy individual. A healthy individual can expire or inspire nearly 6000-8000ml of air per minute or around 12-16 times a minute.
Hence, the tidal volume for a healthy man in an hour approximately can be between 3,60,000 ml and 4,80,000ml.