A question and some answers

Image: (Wikipedia) ” “The Anatomy Lesson of Dr. Nicolaes Tulp” is a 1632 oil painting on canvas by Rembrandt housed in the Mauritshuis museum in The Hague, the Netherlands. The painting is regarded as one of Rembrandt’s early masterpieces.

In the work, Dr. Nicolaes Tulp is pictured explaining the musculature of the arm to a group of doctors. Some of the spectators are various doctors who paid commissions to be included in the painting. The painting is signed in the top-left hand corner Rembrandt. f[ecit] 1632. This may be the first instance of Rembrandt signing a painting with his forename (in its original form) as opposed to the monogramme RHL (Rembrandt Harmenszoon of Leiden), and is thus a sign of his growing artistic confidence.”

From Wikipedia:

“In anatomy, a lobe is a clear anatomical division or extension of an organ (as seen for example in the brain, lung, liver, or kidney) that can be determined without the use of a microscope at the gross anatomy level.”

From researchgate.net: Asked 22nd Feb, 2016:

“Gustav van Niekerk

Stellenbosch University

Why are organs in ‘lobes’?

Your lungs, liver and brain are arranged in lobes- why? Conceivably, lobes could render the body more mobile (e.g. lobes could ‘glide’ over each other, similar to scales on which slide past each other as a fish twist his body), but this argument only make sense for lungs and possibly liver. What is the functional value of growing organs in ‘lobes’?

24th Feb, 2016

Rose Scofield

Oxford Brookes University

Yes interesting! With horses the liver exists in lobes to aid function – so it is related to structure and therefore function like all good anatomy and physiology. As the horse does not have a gallbladder the liver provides a constant source of bile to digest fats in the diet – they evolved this way we think due to their diet being very low in fat and not needing that injection of bile we do when we eat a doughnut! So for horses lobes exist in the liver to provide more surface area for absorption and other cellular functions – we think!

29th Feb, 2016

Karlo Toljan

Cleveland Clinic

Isn’t it just to do with embriology and how the tissue is developed? For example, liver has ‘lobes’ due to various ligaments and previous fetal vessels, but functionaly it is divided into segments (8 of them according to vascularization). Brain lobes are nothing but human anatomical descriptive terms since each brain is individual in its convolutions. For example, anatomists consider prostate to have lobes, etc. There are numerous examples and I think one can be swayed by using anatomical terminology in teleological search for biological design. Maybe sometimes it can coincide to be useful, but then being an exception. 

28th Jun, 2018

John Marini

University of Minnesota Twin Cities

The lobes of the lung are bounded by impermeable fissures, which serve a ‘containment’ function in helping to keep a problem (for example, infection) localized to that region. This would seem likely to have been a strong survival advantage in the pre-antibiotic era. There might, therefore, be an evolutionary explanation of their development. By the way, why do we have two lungs?

29th Jun, 2018

Gustav van Niekerk

Stellenbosch University

Hi John

Your argument makes sense: modular design is a feature that renders biological systems more robust. I guess this line of reasoning works well for the lung, as the lung is not sterile and probably more prone to infections that most other organs. But, why then stop at only 2 (for left) and 3 (right) lobes? Why not say 7 lobes (like cats and dogs)? And also, why then not also ‘lobe-ing’ of other organs such as the kidneys? (Kidneys are probably not as often infected as the lung, but urinary tract infection can often also spread up).

About waving two lungs, I suspect that a partial answer might be because bilateral symmetry is an ancestral trait (i.e. we might be descendants of an animals that use a bilateral body plan for lungs and other organs). This however just shifts the question: why did our ancestor had two lungs.”

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