Parts of Structure

The Common Vein copyright 2008

“The whole organism subsists only by means of the reciprocal action of the single elementary parts”

  Theodor Schwann German physiologist/biologist 1810-1882

“The cause of nutrition and growth resides not in the organism as whole but in separate elementary parts”

 Theodor Schwann German physiologist/biologist 1810-1882

“Every animal is a sum of vital units, each of which possesses the full characteristics of life.  The character and the unity of life cannot be found in one definite point of a higher organization, for example, in the brain of man, but only in the definite, constantly recurring disposition shown individually by each single element.  It follows that the composition of the major organism, the so called individual, must be likened to a kind of social arrangement or society in which a number of separate existences are dependent upon one another in such a way, however that each element possesses its own peculiar activity and carries out its own task by its own powers.”

Rudolph Virchow, German Pathologist/statesman 1821-1902

“I traveled among cells, watched their functioning….and realized that within myself was a grand assemblage of living organisms, all of which added up to me.”

John Lilly American  neurophysiologist/spiritualist 1984

Each person is made of parts. The whole is bigger and usually more powerful than the individual parts.

Courtesy Ashley Davidoff MD 02006p03

In the world that we can appreciate with our own eyes, our microscopes, telescopes and satellites – from the organelles of the cells to the countries of our world – we consistently understand and apply the first concept:  a structure is made up of component parts. This is an elemental thought, observation, and philosophy that goes back to the ancient philosophers.

Democritus of Adbera (northern Greece, 460-370 B.C.),  suggested by philosophical reasoning that all material things were composed of tiny irreducible particles called atoms, which derived from the Greek word átomos  meaning  “uncuttable.”  Aristotle, a philosopher, scientist and physician (343-322BC) stated that “The whole is more than the sum of its parts,”   which remains remarkably true.  Rene Descartes (1596-1650), French mathematician, philosopher and scientist, employed this concept for problem solving.  He is quoted as saying that one should “Divide each difficulty into as many parts as is feasible and necessary to resolve it.”

Jean-Jacques Rousseau (1712-1778)  French philosopher and writer whose novels inspired the leaders of the French Revolution, went on to define the human disposition on these terms by stating that “To live is not merely to breathe; it is to act; it is to make use of our organs, senses, faculties – of all those parts of ourselves which give us the feeling of existence.”

In the context of biology Lewis Thomas wrote in The Lives of a Cell, “I have been trying to think of the earth as a kind of organism, but it is no go. I cannot think of it this way. It is too big, too complex, with too many working parts lacking visible connections. The other night, driving through a hilly, wooded part of southern New England, I wondered about this. If not like an organism, what is it most like? Then, satisfactorily, for that moment, it came to me: it is most like a cell.”

We begin now with Thomas’s idea, eminently relevant to biology, exemplified with the liver cell – a biological unit.  By the end of the book, the concepts promoted by Aristotle, Descartes and Rousseau will hopefully take on meaning as well.

We have chosen the lungs to exemplify the structural concept of units to units  or better still units to unity.


 Parts of the Lungs as an Example

The right and left lung are asymmetric with the right having three lobes and the left two lobes.  The lingula is part of the left upper lobe.

The lung is divided into a right and left lung with the right lung being composed of an upper middle and lower lobe, and the left lung being composed of an upper lobe with the lingula as part of the upper lobe and the lower lower lobe.

Overview of the Parts of the Lung

This image takes you from the person (1) to the alveolus (8,9)- a continuum of structure – each element an individual unit, which in concert work for the harmony of health. Image 2 is a post mortem specimen showing trachea and proximal bronchi entering the lung. The chest X-ray showing the lungs in black within the thoracic cavity (3) is followed by a diagram of the same structure(4), secondary lobule(5), acinus (6), connective support tissues (7), and then the alveoli (8.9).Courtesy Ashley Davidoff MD.

 The journey from the lungs to its component cells starts here.

Click screen to closeThere are two lungs and they are made up of lobes
The post mortem specimen is viewed from the anterior aspect showing the upper lobes in red, the right middle lobe in pink and the lower lobes in green.  Courtesy Ashley Davidoff MD 32558b02
Click screen to closeThe Lobes of the Lung – Posterior View
The same specimen as seen above is viewed from its posterior aspect showing the upper lobes in red and the lower lobes in green.  Note that the lower lobes have a majority of their parenchyma posteriorly while the upper lobes are dominantly positioned anteriorly.  Courtesy Ashley Davidoff MD 32557b01

The lobes are divided into segments and these are discussed inthe individual documents dedicated to each of the lungs.

Radiology – There are two lungs and they are made up of lobes
This P-A view of the chest reveals the position of the normal right upper lobe. Note how much smaller the right upper lobe is compared to the RLL. In this view it is roughly triangular in shape.Courtesy Ashley Davidoff MD. 30397b01
The lobes are made from segments
42644.800 lung pulmonary segments parts fissres normal anatomy heart cardiac chambers Davidoff art Davidoff oneness

The segments are divided into the secondary lobules

The segments form from the Secondary Lobules

Normal lung histology This image of the lung periphery shows secondary lobules and interlobular septa. Within the interlobular septae, one sees small venules and lymphatics. The matrix of the lobule contains alveoliCourtesy Armando Fraire MD. 32649b
Smaller Parts of the Lung – The Secondary Lobule – Key to Understanding
In this remarkable CT we were able to identify a few secondary lobules at the periphery of the lung that have a rectangular shape in this instance.  The branching structure that enters the lobule (blue in b), is characterised as an arteriole for two reasons.  Firstly it is paired with a tubular airway seen in (a) in its most proximal portion as a lucent tubule, and subsequently interpolated in light blue in b.  Secondly it branches in the centre of the lobule.  It is distinct from the border forming interlobular septum  which surrounds it.  A second relatively large vessel colored in red receives a branch from the interlobular septum and by virtue of its size and position it has to be a pulmonary venule.  We know that the lymphatic vessel accompanies the venule, and so the yellow lymphatic has been implied but not visualised.  We also know that connective tissue surrounds these two structures.  In this instance the matrix of the lobule that consists of the alveoli is less dense than it should be and is surrounded by normal alveoli.  Lucency implies air trapping and air trapping implies small airway disease.  Thus this image tells us that the criminal in this case of disorder is the small airway,  We now can focus on the small airways with a pathological differential  diagnosis, and from there plan the treatment.

47152c01 Davidoff MD

The lobules are made up of the small airways including the terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs and the alveoli themselves.

Respiratory bronchioles alveolar sacs, and alveoli
This drawing shows about 3-4 respiratory bronchioles that serve to make a seconadary lobule. Alveolar sacs and individual alveoli are also seen. The yellow border represents the visceral pleura on the surface.Courtesy Ashley Davidoff M.D. 32153
The Acinus
This is a drawing of an acinus. The most upstream component is the terminal bronchiole that has no alveoli associated with it. It’s function is to serves to transport the air to rthe espiratory bronchioles, alveolar sac and alveoli, all of which have the ability to exchange the gases. Courtesy Ashley Davidoff MD. 32186
Grapes of Exchange
An artistic rendition of the alveoli or grape like structure of the alveoli32645a11.800  Courtesy Ashley Davidoff MD
Respiratory bronchiole, Alveoli, Arteriole Capillary and Venule
This is a drawing of a cluster of alveoli surrounded by the capillary network, fed by an arteriole in blue, and drained by a venule in red.Courtesy of Ashley Davidoff M.D. 32164
The Alveolus
This drawing demonstrates the open mouth view of the alveolus, which is surrounded by its capillary network. The lining cells can be seen peaking through the vessels.Courtesy Ashley Davidoff MD.32166
The peripheral alveoli in thisimage abut the pleura in this histological image and they appear in the prepared state to almost have a polygonal sharp angled form.  When filled with air in vivo they are more rounded.  Note thin mesothelial membrane lying on top of alveolated lung parenchyma. This represents the visceral pleura. All structures need protection and at this level the pleura represents the protection for the alveoli

Courtesy Armando Fraire MD 32648

The Cellular Level
This drawing shows the inside of the alveolus and the relationship of the lumen to the wall. In addition the direction of exchange of gases is noted with the carbon dioxide crossing into the alveolus from the pulmonary arteriole side, and the oxygen entering the blood into the pulmonary venous side of the capillaryCourtesy Ashley Davidoff MD 32165
The Cellular Level
Normal lung- Lower magnification Note cup-shaped alveolar spaces outlined by delicate thin alveolar capillary membrane.Courtesy Armando Fraire MD. 32819

Covering – Skins and capsules

All the Coverings to Protect
46701 abdomen pregnancy fetus baby head brain lungs foot knee amniotic cavity amniotic fluid normal anatomy physiology MRI T2 weighted Davidoff MD

Subcutaneous Fat
46698 skin subcutaneous fat dx obesity pregnancy MRI T1 weighted Davidoff MD

Herniated Lung

In this patient rib fractures resulted in a focal defect in the right lower lung field and resulting herniation of the lung.  This is seen in the cross sectional images in a and b, in the coronal reformat in c, and in the volume rendering image in d.

46106c02 Davidoff MD

Self Inflicted Sewing Needles
70038c01 humerus bone elbow shoulder soft tissue foreign bodies sewing needles pyschiatric illness disorder Dvaidoff MD