A Scientific Explanation of the Breathing Process - The Physiology of the Respiratory Organs-asphyxia - Diseases of the Lungs and Chest

Heart and great vessels with lungs turned back There are two lungs, one on each side of the chest, or thorax, and the heart with its great blood vessels lies between

Heart and great vessels with lungs turned back There are two lungs, one on each side of the chest, or thorax, and the heart with its great blood-vessels lies between

The first article of this series dealt briefly with the circulation of the blood. Blood is the vehicle which feeds the tissues with oxygen. The arterial blood carries the oxygen to the tissues; the venous blood takes back carbonic acid gas and other waste substances to the heart and thence to the lungs. In the lungs, this carbonic acid is given off and a new supply of oxygen is absorbed by the process of respiration.

The Respiratory Organs

The respiratory organs consist of the nose, pharynx, larynx, trachea, or windpipe, and the bronchial tubes, which open into innumerable air sacs covered by a fine, dense network of bloodvessels, the whole mass of which form " the lungs." There are two lungs, one on each side of the chest, or thorax, and the heart with its great blood-vessels lies between. The lungs are covered by a fine, transparent membrane, the pleura, which also lines the whole inner surface of the chest.

The lungs are pinkish grey, mottled with black, and in shape they are conical. The bases lie upon the diaphragm, and the apex of each lung extends up to the root of the neck above the collar-bones.

The diaphragm is a sheet of muscle which divides the interior of the body into two. Above the diaphragm lies the thorax, or chest, which contains the heart and lungs. Beneath the diaphragm is the abdominal cavity with its organs of digestion, the stomach, intestines, liver, etc. The diaphragm lies about the level of the waist and descends and ascends with every respiration we take in deep breathing. When the diaphragm sinks and forces the stomach and intestines downwards, the size of the abdominal cavity is reduced and the abdominal wall comes forward with each deep breath we take . Tight corsets, of course, curtail the action of the diaphragm, and that is why women breathe more with the upper part of the chest, and men breathe rather more with the abdomen, using the diaphragm freely. With every breath, the chest walls contract and dilate like a bellows, forcing the air out and sucking it in alternately, thus renewing the air in the lungs.

The "Air Passages" The air is drawn in through the nose and passes down the pharynx, or throat, through the larynx, or organ of voice, until it comes to the trachea.

The air passages. This diagram shows how the tiny bronchi divide and subdivide like the stem of a tree until they are so minute in size they can divide no more.

The air passages. This diagram shows how the tiny bronchi divide and subdivide like the stem of a tree until they are so minute in size they can divide no more.

The trachea, or windpipe, is a strong, cartilaginous tube which passes down the neck to the upper part of the chest, where it divides into two bronchi, one going to each lung.

Now the bronchi divide and subdivide like the stem of a tree until they are so minute in size

Medical that they can divide no more. Each tiny bronchus, therefore, expands into a little sac, or vesicle, almost like a minute balloon.

All round the walls of these air sacs is a network of capillaries, which, as was explained in the previous article, are microscopic bloodvessels. These capillaries contain the venous blood brought from the right side of the heart by the pulmonary arteries, which divide like the bronchi into smaller and smaller arteries until they become so small as to be called " capillaries," filled with venous blood.

Now imagine each little air sac, or alveolus, filled with pure air, which has passed down through the air passages to the furthest extremity of the lungs. The oxygen in this air has to pass through the thin walls of the air sacs, then through the walls of the capillaries right into the blood. At the same time, the carbonic acid gas passes in the opposite direction from the blood through the capillary wall and air sac wall into the interior of the little air sac. From there it passes into the minute bronchus leading from the air sac, thence up the air passages, to be expired into the atmosphere.

How We Breathe

The process of respiration is divided into two stages; inspiration, or drawing in of fresh air laden with oxygen, and expiration, or breathing out of foul air. When we take a breath the chest enlarges because the ribs are elevated or raised by the muscles of respiration and the diaphragm is depressed. The lungs, being practically hollow elastic bags, also expand, and air rushes in through the air passages to fill the vacuum which is produced. With every inspiration about a pint of air is carried into the lungs to mingle with the air which is already present in these organs.

Inspiration is always followed by expiration, which is the forcing out of the air in the lungs by the ribs descending and the diaphragm ascending to their original position. Expired foul air contains less oxygen and more carbonic acid than inspired air, which gives up a large part of its oxygen in the lungs and gains carbonic acid from the venous blood. Expired air is also warmer and moister.

When the blood in the lung capillaries loses carbonic acid and gains a new supply of oxygen, it becomes arterial blood, which is bright red in colour. This arterial blood is carried by the pulmonary veins back to the left side of the heart and is there sent to all parts of the body. All living cells require oxygen for their nourishment, and the oxygen is carried by the red corpuscles in the blood to every organ, every tissue, and every cell of the body.

Asphyxia

If the body is not getting its full supply of oxygen it gradually gets poisoned with carbonic acid gas, and a condition called asphyxia is produced. This may follow upon any obstruction in the air passages, such as in choking or suffocation, when air is prevented from passing down the windpipe. In the same way respiration may be stopped by pressure on the chest walls, and people will die in a crowd from asphyxia because the chest wall is mechanically prevented from enlarging. In drowning, the water in the respiratory passages causes asphyxia because it prevents the air from entering the lungs.

Diagram of air sacs. The oxygen in the air which has passed down through the air passages reaches these sacs and then passes right into the blood.

Diagram of air sacs. The oxygen in the air which has passed down through the air passages reaches these sacs and then passes right into the blood.

It is most necessary for a nurse to understand what respiration is, and to know something of the anatomy of the organs of respiration. One of her duties, especially if she is nursing a "lung case," is to count the respirations, to note whether they are natural or unnatural, shallow or noisy, or irregular. Normally we breathe fifteen to eighteen times per minute. In fever, the breathing is accelerated. In certain illnesses, such as heart disease, breathing may be difficult. In pleurisy, respiration is painful from the friction of the inflamed pleurae against each other.

In the " Dictionary of Ailments " the various lung diseases will be dealt with in detail, and, in a later article, the nursing of these ailments will be dealt with practically, and full instructions given how to treat the various symptoms, such as cough, difficult breathing, pain, etc.

These introductory articles dealing with physiology ought to be referred to by the nurse, in order that she may have an intelligent grasp of what is happening in the body in health and in disease. The nurse who merely treats symptoms mechanically, without knowing the reason why, is not only less useful, but may even be dangercus to the well-being of the patient. It is a good thing to know how to make a poultice for anyone who has a pain, but that sort of knowledge ought not to be the sum of the nurse's curriculum.

Diseases Of The Lungs

The nurse who understands the simple anatomy of the lungs and air passages will, for example, be in a position to understand the difference between bronchitis, pneumonia, and pleurisy. These will be described later in detail.

Meanwhile, it is sufficient to say that Bronchitis is a catarrh, or inflammation, of the bronchia! tubes, and, as is mentioned in the article on colds and catarrhs, it may spread downwards from the nose or throat.

Pneumonia is an inflammation (caused by a special microbe) of the air sacs. These become solid, and in most cases the bases of the lungs are affected.

Pleurisy is inflammation of the pleura covering the lungs and lining the chest walls.

Phthisis, consumption, or tubercular disease of the lungs is inflammation of the lung tissue, caused by the tubercle bacillus. The nursing of phthisis will be given special notice in this series, because good nursing is essential, not only to recovery, but to the prevention of the spread of the disease. In a later article the nurse will learn how to take the temperature, how to distinguish the different types of cough, how to treat pain by poultices and fomentations, how certain positions help a patient to breathe more easily.