The first breaths

Let everything that has breath praise the Lord. Praise the Lord! (Psalm 150:6)


A woman, when she is in labor, has sorrow because her hour has come; but as soon as she has given birth to the child, she no longer remembers the anguish, for joy that a human being has been born into the world.

John 16:21

UNBEARABLE PAIN MORPHS QUICKLY INTO UNTARNISHED JOY for most women upon the successful delivery of a healthy baby. After months of growing anticipation on mom's part and increasing self-assertion on the part of the gradually-developing tiny person, the intense suspense melts away the instant the naked bundle of human potential draws its first breath, opens its eyes, and becomes an independent, real live human being. What greater earthly gift could an all-loving heavenly Father give to His children than the opportunity to participate personally in the miracle of new life? Many obstetricians, believing and unbelieving, feel a sense of wonder at the act of birth right up to their last delivery. (See “Let an expert speak”.)

For those willing to go a step further and give thought to the process of birth and new life, gratitude turns into humble worship; the astounding sequence of wondrous changes that turns a suspended fetus with fluid in its lungs into a squalling babe that breathes air invariably imparts a sense of awe in all who learn about it. Of special note is the remarkable feat performed by a newborn babe when it inhales its first breaths of life. For many of us, taking that first breath may be the biggest challenge we successfully meet in our entire lives! And that is not meant as an insult.

The miracle of breathing

How often do we stop to ponder what's going on when we breathe? Yet the exquisite apparatus by which infants and adults extract oxygen from the air and excrete carbon dioxide into it continues to reveal exciting new Eureka moments to investigators in spite of the many years of intense studies and experiments that have been applied to the system. A number of specialty journals are devoted to the topic, including , American journal of respiratory cell and molecular biology, The European respiratory journal, Paediatric respiratory reviews, Respiratory physiology & neurobiology (formerly known as Respiration Physiology), Lung Cellular and Molecular Physiology, Journal of Pediatric Pulmonology, and Respiratory research. Obviously, then, what we cover in this article will be extremely elementary in scope. But it's enough to stir a song or bring on a poem in any heart. (Unless, of course, the heart believes in the miracle-working power of the big bang, lightning strikes, mutations, and natural selection.)

David praised God for the brilliant design of his own body:

I will praise You, for I am fearfully and wonderfully made; marvelous are Your works, and that my soul knows very well (Ps. 139:14).

Every second endless amazing activities are going on in your body — most at the molecular level —of which you are utterly unconscious and over which you have no direct control. Breathing is one of the few stupendous activities of which you can be aware. Being able to suck in air and blow it out again is sufficient reason in itself to praise God; the level of sophistication and ingenuity of the machinery that makes it happen, not to mention the coordination and control aspects of such a marvel, surpasses full understanding.


Let an expert speak!

"The first breath of a newborn baby must give even the most experienced physician a small thrill of excitement. Until that sudden indrawing of air occurs the baby's life is in doubt, even though the heart is beating… Other problems may be put off for hours, days or weeks, but if the baby is to live, it must begin moving air into and out of its lungs within minutes after emerging from the birth canal. Once the infant is safely past this major crisis the physician takes a few deep breaths of his own and, if he is worth his intellectual salt, may wonder how the act was accomplished. The baby has suddenly emerged, a physiologically displaced person, into an entirely new medium with such novel physical properties it is astonishing that the infant is able do deal with it so promptly and effectively. The infant is called on, in one sudden moment, to replace the gestational system of oxygen supply and carbon dioxide disposal by the placental circulation with a new system employing the hitherto unused lungs … How impressive this performance is cannot be appreciated until one examines the obstacles the baby must surmount in drawing its first breath. It is born with its lungs and air passages probably distended by fluid, and against this and other resistances it must inflate the lungs, keep them inflated between breaths and quickly establish a breathing pattern."

Clement Smith, The First Breath, Scientific American, October 1963


Humans have two lungs, with the left being divided into two lobes and the right into three lobes. Most adults breathe about twelve times per minute at rest (the normal range being anywhere between 10 and 20 times), sucking in about 500 ml of air — the equivalent of eleven liquor jiggers — each time. A little investigation reveals that an entire suite of anatomical and physiological design features, ranging from the microstructure and chemical lining of tiny alveoli to the large-scale anatomy of ribs, is needed to make the breathing machinery work effectively. Large-scale features, such as the shape and composition (and therefore elasticity) of ribs, the placement and power of respiratory muscles such as the diaphragm, and the properties of the pleural membranes (see below) work harmoniously together to provide suction pressure for inhalation and “blow” pressure for exhalation, while the microstructure of lung tissue and the properties of chemicals lining the microscopic airways are contrived to give easy passage of air to the lung's internal extremities and to keep delicate airways open.

Perhaps the best way to picture the structure of the breathing apparatus is to imagine an upside-down tree. The inverted trunk represents the windpipe (trachea) which divides into two branches (bronchi), one for each lung, which in turn branch further into a mass of twigs (the bronchioles) at the ends of which are found clusters of tiny leaves (in reality more like bunches of grapes), representing what are called the “alveoli”. Combined, the airways in an adult stretch out about 1500 miles (2,400 km) and the alveoli have a total surface area of about 75 m 2 in adults — roughly the same area as a tennis court.

Alveoli are tiny air sacs that act as the primary gas exchange units between air and blood. Millions of alveoli make up the lungs — about 25 million at birth reaching some 85 million by the time the baby reaches three months1 and about 300-700 million by adulthood. Such a huge number contained in a small volume leads to a simple deduction — alveoli are not just tiny, they are microscopically small. You cannot see them with the naked eye; cut open a lung and you would see what appears to be almost solid matter yet it is, in fact, like an extremely fine-grained, delicate sponge. The wall that separates the air in the “wide open spaces” of the tiny sacs from the labyrinth of delicate blood vessels that ramify throughout the fine tissue consists of only a vital thin film of liquid wetting agent, or surfactant, and two layers of cells separated by a microscopic space.

The fine blood vessels (capillaries) on the inside of the fine barrier have room for only one or two blood cells at a time to squeeze along the tunnel. If all of the capillaries that surround the alveoli were unwound and laid end to end, they would extend for about 620 miles (990 km). Oxygen and carbon dioxide molecules move by diffusion between alveolar “bubbles” and capillaries through tiny pores that make the barrier permeable. Roaming, amoeba-like white blood cells crawl around the inside lining of the alveoli and sweep them clear of bacteria and other foreign particles by engulfing them.

Of lungs and balloons

To better understand what happens when we breathe, we need a little basic knowledge about those masterpieces of precision engineering, lungs and chests. From a mechanical perspective, the lungs are a kind of collapsible hollow cylinder located inside a rigid, potentially hollow object, the chest wall, of which the rib cage comprises the key component. Both lungs and rib cage share a property known as elastance, meaning they are naturally “sprung” to attain to a specific shape and size when no external forces act on them to either distend or compress them, and that they will tend to “spring back” to their default dimensions after being distorted in any way. Hark back to your childhood balloon-blowing days. A balloon is sprung to be almost totally empty at rest; let one go after blowing it up and watch it rocket around the room as it elastically recoils to normal.

Unlike kitchen sponges, which automatically “bounce back” to an expanded state after being squeezed, lung sponge, consisting of a mesh of alveolar epithelia,2 capillaries, and elastic and collagenous fibers is sprung like a balloon so as to go the other way; its springiness is “negative” (loosely speaking), meaning that it would completely collapse and squeeze all the air out if surgically removed from inside the thorax3 which holds them partially open.4 (The springiness operates in both directions; lungs will also spring back after being compressed.) Of importance is a marvelous truth about lungs — elastance increases progressively with the degree of distortion.5 The further they are pumped up, the more they resist being pumped up. Inflating them gets harder and harder the more they are inflated. Try it for yourself. Exactly why this should be so may be far more complicated than we think.

Unlike lungs, ribs and attendant cartilage are beautifully and precisely designed to spring open a little, and thus draw in air, if left entirely to their own devices. Paradoxically, in this respect they are more like a kitchen sponge than spongy lungs are! Just as lungs resist being pumped up the more you pump them, the more you seek to compress the chest wall, the more it resists. Try breathing out as much air as possible and you will experience this amazing property firsthand.

The elastance properties of both lungs and chest wall are exquisitely fitted to making breathing at rest as easy as possible. Both lungs and chest are so sprung that they pose very little resistance to being distorted to the limits of relaxed breathing. The lungs barely fight back when inflated by about 500 ml during air intake; likewise, the ribcage makes very little fuss when compressed during exhalation. Small changes of pressure in either direction thus produce a large change in the amount of air that is inhaled and exhaled. The diaphragm, built for heavy duty work when necessary, spends most of its time “lifting feathers”.

Sprung just right

When breathing apparatus is totally relaxed it is said to be at rest. In the breathing cycle, relaxation occurs at the end of exhalation. At that moment the opposing forces — the “force of collapse” exerted by the lungs and the tendency of the chest wall to spring open — exactly balance each other; no muscles are working. At that point, both lungs and rib cage are under a degree of stress since neither is exactly the way it would like to be, neither is at default.

An obvious implication of this friendly antagonism is that some air will remain in the lungs after expiration; the tendency of the rib cage to expand prevents the lungs from squeezing all the air out. Which is why you can force more air out of your lungs after you have reached the natural end of expiration. (But even after your most strenuous effort to exhale all the air, some air, known as the residual volume, is still left behind.) The volume of air that remains in your lungs after you have exhaled is known as the functional residual capacity (FRC). Life without this ever-present bank account of gas would be impossible. In addition to the critical function of keeping the airways propped open, the FRC makes some more mundane things possible:

Life without this ever-present bank account of gas would be impossible.

Without this air, eating, drinking, talking and other essential activities would be severely limited by the necessity of continuous breathing.6

May we praise and thank our Creator for making us thus.

The concept of balance between the opposing elastic forces of contraction by the lungs and expansion by the ribs and chest wall may be easy to grasp. However, to maintain the FRC at just the right volume to fulfill the needs just mentioned, not to mention all the other aspects of breathing, requires highly sophisticated engineering. The anatomy and material composition of every part must be just so, and the parts must be joined one to another with absolute precision and just the right degree of flexibility. Soft parts, such as the lungs and pleura, must be glued to each other or to the hard parts (ribs and cartilage) effectively — a feat in its own right. Of course, educated people today realize that such wonders of precision engineering were not conceived by a supreme intelligence but mindlessly contrived by natural selection. Pigs will fly! One cannot help but shed a tear of compassion for the poor beggars of wheezing, gasping, incipient air-breathing species that had to wait millions of years for natural selection to perfect the anatomy, histology,7 biochemistry, and materials physics of lung and chest components.

The FRC of adults makes up 35-40% of their total lung capacity (the volume of lungs when expanded as far as possible) of 4000 to 6000 ml. Researchers have found that in newborns it would amount to only 15-20% if the infant breathed all the way out to the rest state,8 a fact that has the potential for causing serious problems. Before we speak about the problem, let's try to understand why infants' lungs potentially harbor proportionally less residual air than adults' lungs do. It's all a matter of this thing called elastance; high elastance means stiffness (low compliance9) while low elastance (high compliance) means suppleness. The nature of human reproduction imposes certain constraints on the physical makeup of the fetus to enable it to squeeze safely through the narrow birth canal. Partly as a result of this fact, babies are not just miniature adults; among other things, their bones are softer and more flexible than those of adults. A newborn's chest is considerably more supple, or compliant, than that of her mom and dad. It takes a few days to develop more outward recoil. 10 The point of balance between the opposing forces in an infant therefore pitches in favor of the lungs rather than the chest cavity so that the FRC is lower. Elastance/compliance of the lungs themselves is already sealed by birth and undergoes very little further change.11

Diagram of apparatus used for respiratory studies on infants (The Journal of Clinical Investigations, Vol. 36, 1957)

Were a newborn to breath all the way out to FRC the significant reduction in gas reserves would bring the entire breathing system perilously close to shutdown. In a nutshell, like balloons being left to deflate as a result of their own elasticity, the airspaces and alveoli of the lungs would spontaneously close if insufficient air is available at a pressure slightly higher than external air pressure (atmospheric pressure) to keep them open. 12 The deflation process would take 24–48 hours; the end result would be death.13 This potential problem had to be solved. How it was done will soon be revealed. But first…

Mechanics of breathing

What mechanism causes air to enter and leave the lungs? As we have seen, lung tissue is like a sponge. Covering the sponge is a two-layered membrane known as the pleura, the two membranes (pleurae) being separated by a potential space. We can liken the entire setup to a sponge enclosed in two balloons, the one balloon inside the other. What sort of mechanism would you rig up to suck air into sponge-filled balloons? The answer lies in placing the sponge-balloons inside a rigid container, gluing or stitching the balloons to the inner walls of the container, and then contriving a means of making the container expand, pulling on the outer balloon which sets up a negative pressure (suction) in the gap separating it from the inner balloon, which pulls on the inner balloon which reduces pressure inside the sponge's air spaces and… well, you can imagine the rest. Bellows design is based on this principle. In breathing, the ribs provide the required rigidity.

The force to expand the chest cavity is generated by the muscles of respiration.14 The workhorse muscle is the diaphragm, but it needs the assistance of other precision muscles (external intercostals, scalene muscles, and sternomastoids) to tug gently on other parts of the rib cage to harness the diaphragm's horsepower in such a way as to have the desired effect. All these muscles must work in perfect concert, requiring an unbelievably sophisticated, brain-and-nerve-controlled coordination mechanism. And all this regulation occurs without our being the slightest bit aware of it.

By contrast with inhalation, the diaphragm and other respiratory muscles relax during exhalation when breathing at rest so that breathing out is passively caused by the elastic tendency of lung tissue to collapse. Exercise induces the diaphragm to enter a new phase in which it actively contracts to drive the air out more quickly and thus enable a more rapid respiratory rate.15 The rib cage apparently is not involved in expelling air in rest breathing: inhalation does not distend it above its default size.

Breathing in the newborn infant

Significant differences occur between infant and adult breathing phenomena which reflect underlying differences in their respective respiratory systems. Though such differences may come as no great surprise, they nevertheless attest to the wisdom and ingenuity of the Creator of all things, Who not only had to design the respiratory system of adults, but also had to ensure that the gradual changes on the way to maturity all matched the gradually changing needs of the individual. Changes over time don't just happen by good luck; they are carefully regulated by one's genes. One small cockup by just one gene anywhere along the path to maturity could spell disaster for mankind. The population explosion attests to the thoroughness of the Master's planning. Forget natural selection; it couldn't accomplish such a thing in a million years. Sorry, millions of years.

One small cockup by just one gene anywhere along the path to maturity could spell disaster for mankind.

These comments raise a fundamental truism about human development — the change from babyhood to adulthood involves much more than merely growing bigger. Critical developmental changes must occur in all bodily systems day by day. Lungs and chests don't just get bigger, they develop. The first days of life are the most critical. Millions of microscopically-narrow tunnels (bronchioles) must quickly “learn” to allow the efficient passage of air into the millions of alveoli which, having been charged with air in the first breaths, must then inflate and deflate in perfect harmony and rapid succession, a process known as ventilation. (Asthmatics don't take the ability of bronchioles to let air squeeze through them for granted.) Efficient ventilation takes a few days to establish.16 The supple chest wall, having been released from its fetal straitjacket, must stiffen ever so slightly to increase its recoil strength sufficient to force the lungs to hold on to a little air after exhaling. Regular breathing patterns must be established, and so on.

Increased respiratory rate

One vital development involves the rate of respiration. Compared with adults, who breathe about twelve times per minute, the respiratory rate of infants is considerably higher. The data from different researchers varies considerably.17 A figure of 50 breaths per minute in the first days of life can be taken as a fair approximation. That's four times faster than the adult rate. What's going on? In earlier days of respiratory research, the causes of the elevated rate were tied to such things as basal metabolism (infants have a larger surface area to volume ratio than adults do). After that, an explanation was sought in such things as, “pulmonary compliance, elastic and viscous resistance and the work of respiration”.18 All of these factors undoubtedly are involved, but trying to discover what is the most immediate cause and which is secondary, tertiary, and so on, is a bit like trying to figure out how a particular game of chess was won.

Clearly, the elevated rate must be of some advantage to the newborn; the general conclusion of experts in the 1950s went like this:

… the more rapid and shallow respiration may be a mechanically advantageous adaptation to physical factors peculiar to the lungs and chest of the newborn infant.19

In short, it works this way because that's the best way for it to work. With such a conclusion believers in creation can heartily agree. How exactly we survived before we developed the evolutionary adaptation of fast breathing remains a mystery.

Later research has given us some truly intriguing insights into the most immediate cause of the high respiratory rate in newborns and a faith-building explanation of why it happens. Let's deal with the why first. It takes us back to the serious problem mentioned earlier; if newborns were to breathe all the way out to relaxation their entire system would become unstable and shut down. A minimal quantity of air is needed in the peripheral areas of the lungs for the critical function of keeping the tiny bronchioles and alveoli open, but the low elastance (high compliance) of the young chest wall would not be up to the task of dynamically holding even that minimal amount. Rapid breathing solves the problem! In brief, rapid breathing means shallow breathing, meaning there is simply not enough time for the diaper-wearer to breathe all the way out. Let Olinsky explain:

With a rapid respiratory rate… time is not available for passive expiration to functional residual capacity. Therefore… the end-expiratory level will be higher than the passive FRC… Therefore, the rapid respiratory rate… may be [an] important factor[s] in maintaining the lung volume in neonates until the thorax develops more outward recoil.20

It takes about three days for the soft ribs and cartilage of the chest wall — which need to be soft for birth to succeed — to cure. Rapid respiratory rate solves the problem of the potential systemic crash. But how is it maintained for just the right amount of time needed for thorax hardening to occur? The main controlling factor has been found in an amazing reflex.

The inflation reflex

Who can forget childhood medical checkups when the doctor would, among other things, tap your knee with a small rubber hammer to check your jerk reflex. Reflex actions are those in which a special wiring, known as a reflex arc, of the nerves between some location of the body and the spinal cord produces an involuntary response to a stimulus in that location even before the message reaches the brain and you have a chance to think about what's going on. Put your hand on a stove hotplate and you will retract it almost instantly, perhaps even before you become aware of the pain. Reflex arcs are only activated by certain defined stimuli. Putting your hand on ice will not elicit the same instant response.

Put your hand on a stove hotplate and you will retract it almost instantly, perhaps even before you become aware of the pain.

For about three to seven days after birth, newborn infants have their very own reflex that we adults don't have. The breathing cycle in adults is controlled by an inbuilt pacemaker, the bulbopontine pacemaker, which transmits nerve impulses to the lungs without any conscious effort on our part. This centrally-controlled mechanism has some involvement in the breathing of a newborn. However, the inflation reflex tends to override it for a few days. In the infant, ingeniously-designed stretch receptors in the lungs are critically sensitive to stretching during inhalation. As the lungs expand, the receptors send a feedback signal to the reflex arc centered in the spinal column; when they reach a certain intensity (after about one second of inflating) a reflex impulse signals the diaphragm to have a short rest, whereupon the elastic lungs immediately begin to contract and drive out air. This reflex operates at a sizzling speed compared with the pacemaker. Voila. Concerning such mechanisms in infants, Baldwin and others reflect that, “Biological feedback systems… are reflective of engineering control systems and may be modeled using similar mathematical concepts”.21 Hmm. Brilliant.

Stop and think. If you live for 25,000 days (about seventy years), the built-in reflex lasting just four or five days operates for a vanishingly tiny portion of your life. Yet it spells the difference between life and death for you. Who organized to switch on such a short-lived reflex at just the right moment in life? As Olinsky says, “… the system must function immediately after birth” (p. 428). You can rest assured natural selection does not have the accidental genius required to do such a thing.

This reflex is not the only mechanism provided by an all-wise Creator to ensure a sufficient volume of air is retained in the lungs after expiration. For example, one reflex kicks in to ensure that deflation ceases before lung volume drops too low. In this case, “rapidly adapting receptors” sound the alarm when lung volume is suddenly reduced; the reflex arc sends a signal immediately to the diaphragm to restart inspiration.22 Yet more vital factors come into play. They are summarized by Bradley Thach:

Previous studies have discovered an array of interdependent, vagally mediated [controlled by the vagus nerve] mechanisms that function to increase both average and end-expiratory lung volume in newborns…23

God's concern for human survival is so intense He has applied the “belt and suspenders” principle to the task of keeping a baby's lungs functioning. One other possible means of helping prevent collapse of alveoli and small airways is…

God's concern for human survival is so intense He has applied the “belt and suspenders” principle to the task of keeping a baby's lungs functioning.


Sighing is another short-lived reflex in newborns. At least once every five minutes, a newborn “sighs”, that is, takes a deep breath that sucks in slightly more than double the normal breath intake. By the fifth day the incidence of sighing has dropped in most infants, but still occurs periodically (see graph below). Detailed study has shown that what appears to be one continuous, prolonged intake of air actually consists of a normal breath, interrupted momentarily by a pause or even a very slight exhalation followed by a second, bigger renewed inflow of air often called a “gasp”. This phenomenon is called a “breath on top of a breath”.24 The second gasp is initiated by a reflex that is activated when, for reasons that seem unclear, the first breath is ever so slightly larger or faster than normal. The subtle deviation from normal of the first breath triggers the next intake. The changed first breath may be caused by a response in the central nervous system to changes in blood chemistry, perhaps related to levels of oxygen or carbon dioxide in the blood.

Frequency of spontaneous sighs for seven infants at 24 hours and 5 days age. Note that the reflex is weakening by the fifth day, but that all infants studied still sighed at least once every ten minutes. (Thach & Taeusch 1976)

Of considerable interest to respiratory experts is the purpose of sighing in infants. They recognize that it doesn't just happen because it just happens. Many ideas have been proposed. Some suspect that it plays a role in maintaining the vital suppleness (preserving compliance) of the lungs. A recent study suggests that sighs, “… play an important role in resetting the mechanical properties of the lung tissue and airway walls”.25 Still others believe it plays a role in solving the potential problem of lung collapse just discussed by blasting open isolated segments that get blocked. Keeping the staggering labyrinth of airways open and allowing air to move around evenly requires brilliant innovations; sighing is probably one of them. In short, sighing appears to play a number of vital roles; experts are still busily at work discovering new things about a seemingly incidental feature of breathing in babies.

Wetting agent

In the 1950s, medical researchers Avery and Mead discovered the fundamental reason why some babies suffer with breathing difficulties (respiratory distress syndrome) — affected babies are unable to lower surface tension in the critical zone of gas exchange, down among the alveoli.26 This basic truth has led researchers into a whole new world of wonder, the world of the pulmonary wetting agent, or surfactant. Believe it or not, in November, 1989, dozens of scientists embarked on a “floating congress on the River Rhine… to celebrate 60 years of surfactant research”.27 This stuff is just that important and remarkable. Shortly before birth special cells lining the alveoli called alveolar type II cells, which cover about 5% of the alveolar internal lung surface,28 pump this amazing liquid into the alveoli, thus preparing the way for the first breath and every other breath one ever takes. (For a drawing of alveolar type II cells, click here.)

This miracle fluid, consisting of 90% lipids and 10% protein, acts like a gardener's wetting agent. Try spraying water on citrus leaves; instead of spreading evenly over the surface of the leaf the liquid contracts into little globs as a result of surface tension. The addition of a wetting agent such as soap, by marvelous laws of physics and chemistry, reduces the tension and ensures an even spread.

Now, the surface tension of liquid lining tiny alveolar bubbles sets up a contracting force that would, if not counteracted, lead to collapse. Surfactant reduces the tension, thus reducing the tendency to cave in. This effect reduces the amount of inflatory pressure that would have to be supplied by other mechanisms after the lungs have deflated in order to prevent collapse.

This wonder liquid also acts as a barrier to blood serum that would otherwise leak in from the blood vessels and choke the tiny air sacs, causing us to drown in the open air. It also helps prevent a buildup of water on the inside lining of the alveoli due to condensation of water out of the air we breathe in. So without surfactant we would be in big trouble.

So without surfactant our alveoli would collapse, and if that didn't happen we would eventually drown in the open air.

We haven't finished with surfactant just yet. One of the most amazing thoughts to pursue about efficient breathing is just how precise must be the forces acting on alveoli during both breathing in and breathing out. Obviously, if we are to breathe at all, the alveoli have to wrinkle and shrink a little when we breathe out before returning to full size seconds later; but they must not completely empty or it would take a huge effort to prise them open again. Since alveoli are microstructures, the forces involved with each inflation and deflation are micro-forces. To work perfectly, the mathematics of the forces involved to produce the desired level of deflation have to be spot on. For mechanical reasons, the surface tension in alveoli has to adjust itself constantly with inflation and deflation throughout the breathing cycle if the alveoli are to remain stable! The continuous change must be precisely micro-regulated micro-moment by micro-moment. We should not overdo the word “miracle” when talking about creation or it begins to lose its value. But the ability of lung surfactant to precisely decrease surface tension as the alveoli shrink and increase it again as they expand can be viewed as nothing less than a miracle of planning and engineering. To get a firm grip on what's going on you would probably have to study physics, chemistry, and mathematics for a long time.

Surfactant also plays a vital role in…

The first breath

Of all the amazing post-natal events that occur over the course of a few days, the gold medal for sheer drama must go to the act of taking the very first breath. At the moment of birth, a newborn infant doesn't have a molecule of gas in her lungs. The airways are filled with a small amount of fluid pumped into the lungs before birth by means of hydraulic pressure.29 This fluid is a mix of the surfactant just referred to and other fluids.

The first breath, then, must overcome huge obstacles. First, you have the natural resistance posed by the narrowness of the airways in the tiny lungs. Illustrating this problem is easy enough. Open your mouth wide and suck in a lungful. Now put a straw in your mouth and try to do the same thing. Smaller passageways mean more resistance to the flow of air. That we adults can breathe is marvelous enough — that a tiny package of new life can do so for the first time should be enough to blow us away. Researchers have found that even more resistance (about 70% of the total) comes from the peculiar elastic properties of alveoli and airways and the liquid lining them.30

A comparison of the first breath (lower loop) with a breath at one day of age (top loop). Note that before the first breath the lungs contain no air at all. At the end of the breath, functional residual capacity is immediately achieved; about 15 ml of air remains. The first breath takes in about 45 ml of air. 24 hours later, FRC is about 90 ml, far less pressure is generated, and only about 15 ml of air is inhaled. (Mortola 1987)

But there is more. Imagine the straws just mentioned were filled with water — the resistance to drawing in air makes the task so much harder. Further, the first breath meets resistance from the tissues of the lungs themselves.31 In sum, for a newborn, “the pressure required to inhale is very large”.32 Yet as a newborn baby, because of the planning and preparation of your Maker, you succeeded in pushing that fluid in your airways out of the way in that very first breath!

For this first inspiration of air, the diaphragm, assisted by upper airway muscles,33 marshals all its resources to make one Herculean effort. Though its action may be assisted by a swallowing action of the tongue and throat resembling the forced swallowing breathing of a frog,34 the evidence supports the contention that almost all the air that enters the lungs in the first breath does so through the contraction of the respiratory muscles.35 As the first breathing movement begins, the chest narrows momentarily, air begins to enter the pharynx, and then, a third of a second later, a considerable amount of air reaches the lungs. The resistance the air meets from surface tension at the air-liquid interface as it passes into the deepest portions of the lungs, the bronchioles and alveoli, is considerably offset by… yes, you guessed it… the wetting agent that reduces the surface tension. When they have received all the air the newborn can force in, the diaphragm relaxes and the first exhalation occurs. The very first breath succeeds in stocking the lungs with a small amount of residual air; never again will they be completely empty. Many more breaths are required to ventilate all the internal airways and alveoli evenly. But never again will as much effort be required as was necessary for that first breath.

What happens to that fluid that is heaved and pushed down, down, down into the very margins of the lungs in those very first breaths? It is rapidly reabsorbed! What cues the epithelia of the alveoli to reverse the direction of pumping? Wonder of wonders! If the merest contemplation of such marvels is not enough to make us drop on our knees in worshipful admiration of the Creator, one wonders what can.

If the merest contemplation of such marvels is not enough to make us drop on our knees in worshipful admiration of the Creator, one wonders what can.

When one has some grasp of the sophistication of design of the human breathing apparatus, and what it takes to activate the first breath after birth, the allusion to breath in Isaiah 42:5 takes on a whole new meaning:

Thus says God the Lord, Who created the heavens and stretched them out, Who spread forth the earth and that which comes from it, Who gives breath to the people on it, and spirit to those who walk on it…

Those tiny bundles aren't just cute, cuddly and adorable; they sing the praises of the Father and Jesus Christ Who not only care passionately for each one — even more than her mother does — but Who spared no effort to ensure that they can conquer the mile-high hurdles confronting them when they emerge into their wondrous new world of adventure and excitement. At the same time, the sheer genius of the respiratory system should fill us with an appropriate sense of awe for “the God who holds your breath in His hand” (Dan. 5:23).

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If you found this article interesting, you will want to read the chapter "Fearfully and wonderfully made" from the Dawn to Dusk book "Jacob's Multi-colored Dream Goats".

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References and notes

1 Smith, Clement A. October 1963, The First Breath, Scientific American, p. 28

2 Relating to epithelium, which is any tissue which covers a surface (such as the living part of skin) or lines a cavity such as the airways or alveoli. Epithelial tissue performs protective or secreting functions, or both.

3 Chest

4 Smith, p. 30

5 Mead, Jere, and Whittenberger, James L. June 1 1953, Physical Properties of Human Lungs Measured During Spontaneous Respiration, Journal of Applied Physiology, Vol. 5, Issue 12, 779-796, p. 779

6 Smith, p. 31

7 The microscopic structure of tissues

8 Olinsky, A, Bryan, M. H., and Bryan, A. C. April 1974, Influence of lung inflation on respiratory control in neonates, Journal of Applied Physiology, Vol. 36, No. 4, p. 428.

9 Compliance is the reciprocal of elastance. The more strongly elastic something is, the less compliant or supple it is, and vice versa.

10 Olinsky et al, p. 429

11 Frappell, Peter B., and MacFarlane, Peter M. 2005, Development of mechanics and pulmonary reflexes, Respiratory Physiology & Neurobiology, 149:143-154, p. 148

12 Olinsky, p. 428

13 Thach, Bradley 2001, Fast breaths, slow breaths, small breaths , big breaths: importance of vagal innervation in the newborn lung, Journal of Applied Physiology, 91:2298-2300, p. 2298

14 Respiration is the big word for breathing

15 The number of breaths per minute

16 Nelson, Nicholas M., Prod'hom, L. Samuel, Cherry, Ruth B., Lipsitz, Philip J. And Smith, Clement A. 1963, Pulmonary function in the newborn infant: the alveolar-arterial oxygen gradient, Journal of Applied Physiology, 18: 534-538, p. 534

17 Orlinksy and others say that, “… the newborn infant is breathing between 40 and 60/min” (p. 428). Mortola says that, “… in the first 90 min it averages between 70 and 90 breaths/min” (1987, p. 199). Thach puts the rate “at one day” of age as 54 per minute (1976, p. 504). These figures are quite at variance with those of Cook and others who report that the rate varied between 23 and 49 in 26 infants studied between 5 and 24 hours of age (1955, p. 976), taking 34 breaths per minute as an average (p. 980). Thach, however, says that, “There were no significant differences in… overall respiratory frequency at 1 day (54/min) compared to 5 days of age (55/min) (1976, p. 504). As for the length of time rapid breathing lasts, Mortola says rapid breathing, “… usually subsides within 1 day” (p. 199). However, a drop to 50 per minute could class as a subsidence of rapid breathing if the starting rate is 70-90.

18 Cook, Charles D., Cherry, Ruth B., O'Brien, Donough, Karlberg, Petter, and Smith, Clement A. July 1955, Studies of Respiratory Physiology in the Newborn Infant. I. Observations on Normal Premature and Full-term Infants, The Journal of Clinical Investigations, 34(7 Pt 1): 975–982, p. 980

19 Cook et al, p. 980

20 Olinsky, pp. 428-429

21 Baldwin, D. N., Suki, B., Pillow, J. J., Roiha, H. L., Monocchieri, S., and Frey, U. 2004, Effect of sighs on breathing memory and dynamics in healthy infants, Journal of Applied Physiology, 97:1830-1839, p. 1830

22 Frappell & MacFarlane, p. 149

23 2001, Fast breaths, slow breaths, small breaths, big breaths: importance of vagal innervation in the newborn lung, Journal of Applied Physiology, 91:2298-2300

24 Thach, Bradley T. and Taeusch, H. William October 1976, Sighing in newborn infants: role of inflation-augmenting reflex, Journal of Applied Physiology, Vol. 41, No. 4, 502-507 , p. 502

25 Baldwin et al, p. 1830

26 Floros, Joanna April 1990, Sixty years of surfactant research, AJP — Lung Cellular and Molecular Physiology, Volume 258, Issue 4, p. L238

27 Floros, p. L238

28 Shannon, John M., and Hyatt, Brian A. 2004, Epithelial-mesenchymal interactions in the developing lung, Annual Review of Physiology, 66:625–645, p. 625

29 Mortola, Jacopo P. January 1987, Dynamics of Breathing in Newborn Mammals, Physiological Reviews, Vol. 67, No. 1: 187-243, p. 191

30 Frappell & MacFarlane, p. 145

31 Smith, p. 30

32 Mortola, p. 193

33 Mortola, p. 194

34 Smith, p 31

35 Mortola, p. 193

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