The Schematic Circulation of the Blood

Another diagram found almost ubiquitously in textbooks of anatomy and physiology is a schematic representation of the circulation(s) of the blood. I say 'almost ubiquitously' because I have never found a textbook in which some such diagram has never appeared... but there may be one out there somewhere. I also use the word 'circulation(s)' because human blood circulates in a figure of eight. One circuit is referred to as the systemic circulation, the other the pulmonary circulation. 

Despite the conceptual simplicity of the circulation of the blood, the diagrams one finds in textbooks vary markedly. I shall share some of those I have collected from time to time. To begin, this version comes from Wikipedia:

As with all diagrams, there is simplification, conceptualisation and questions arising as a result. The more commonly a diagram is found in a textbook, the more it should be scrutinised. New textbooks take their lead from old textbooks. Some things are included because they have always been included; their exclusion might be deemed an omission. (Nobody wants a bad review.)

Is this the best such diagram? Does it make its point as well as it could?

Cells typically stay separate

Cells are often described as the smallest unit of life. That applies to both uni- and multicellular organisms. This is a characteristic they maintain as long as they survive. As such, they possess an ‘individuality’.

To the benefit of the organism as a whole, some cells divide while others, also to the benefit of the organism, do not. Still others may usefully disintegrate - as in the case of megakaryocytes which give rise to platelets important in blood clotting.

Obvious - yet rarely stated - is the fact that cells do not typically merge with other cells. Here, the fusion of sperm and ova is seen as a special case. Each contains only 23 chromosomes and so only half of the entire genetic material. Thus, sperm and ova are - in a sense - only half cells. (Indeed, whether sperm qualify for the title ‘cell’ is a moot point.)

With very few exceptions, cells remain separate from each other throughout their lifespan. They do not blend or merge to form mega-cells. Those cells that do fuse do not fuse with cells of another type. They fuse only with cells of the same type. In so doing they become multinucleated. The cytoplasm is combined but not the nuclei. In this, a hint of the ‘individuality’ I mentioned above, persists.

What does having two nuclei within the same cytoplasm imply? In practical terms, there is an increase in the efficiency of the cell. (If by cell we mean that bounded by the cell membrane.) It implies double input/output and information processing capacity.

Those cells in our bodies that do undergo fusion do so in specialized circumstances, such as during development and tissue repair. For example:

1. Muscle Cells: Muscle cells, known as myocytes, can fuse to form multinucleated muscle fibres. This process contributes to the growth and repair of skeletal muscle tissue.
2. Osteoclasts: Osteoclasts, which are responsible for bone resorption, are formed by the fusion of monocyte/macrophage precursor cells.
3. Syncytiotrophoblasts: In the placenta, syncytiotrophoblasts are formed by the fusion of cytotrophoblasts. These multinucleated cells play a crucial role in facilitating nutrient and gas exchange between the maternal and fetal circulations.

Cell fusion is not a random process. It is tightly regulated and involves complex molecular mechanisms. This implies that cell fusion is a process that has evolved. As such, it offers the organism a biological - that is, a survival and/or reproductive - benefit. To use a word rarely used biologically, it is ‘deliberate’.

Having introduced this word, I will stop here and ponder what, in a biological context, ‘deliberate’ means and how it might be used.

Deconstruction

I originally entitled this blog - ‘Deconstructing Humpty’. (I still apply the phrase in private to the wider project upon which I am working.) The word deconstruction is most commonly associated with the French philosopher Jacques Derrida (1930-2004). What did he mean by this term?

Derrida introduced the concept of deconstruction to refer to a method of critical analysis primarily applied to texts and discourse. At its core, deconstruction challenges traditional notions of binary oppositions and hierarchies by exposing the inherent complexities, contradictions, and ambiguities within them. It involves unravelling the layers of meaning in a text to reveal the underlying assumptions and biases, often highlighting the presence of marginalized voices or alternative interpretations.

Deconstruction does not seek to dismantle or destroy meaning but rather to explore the multiple interpretations and possibilities that exist within a text. It emphasizes the fluidity and instability of language, suggesting that meanings are not fixed but are constantly shifting and evolving based on context and perspective.

Derrida argued that language is inherently unstable, and attempts to fix meaning ultimately lead to exclusion and marginalization. Therefore, deconstruction aims to disrupt the binary oppositions that structure thought and language, opening up new ways of understanding and engaging with texts and ideas. It encourages readers to interrogate texts and discourse to uncover hidden assumptions and explore alternative interpretations.

This is something I am exploring applied to human bodies and our being physical entities. Borrowing some of Derrida’s ideas gives a different perspective on how the human body is understood.

An alternative title I often bandy with is 'Reconstructing Humpty'. I shall begin to describe what this means at a later date. (I say 'begin' because it is an ongoing process.)

Continental Philosophy

Philosophy is often frowned upon by scientists. They see themselves as engaged in unravelling the mysteries of nature by doing laborious practical work while philosophers do their work from the comfort of an armchair. The type of philosophers that those in English-speaking countries criticise are referred to as analytic philosophers. They are the type of philosopher with which they are most familiar.

Analytic philosophy is a philosophical tradition that emphasises clarity of language, logical rigour, and precise analysis of concepts. It emerged in the early 20th century mainly in the English-speaking world. Analytic philosophers typically focus on breaking down philosophical problems into manageable components. Problems are solved using techniques such as formal logic, linguistic analysis and the scrutiny of ordinary language.

Thus, analytic philosophy shares much in common with science. However, it is not the only form of philosophy practised. Continental philosophy is a branch of philosophy that originated in continental Europe, especially in the 19th and 20th centuries. Characteristically, it emphasises human experience, culture, and society. It explores concepts like existentialism, phenomenology, hermeneutics, and structuralism. It is more personalised than analytic philosophy or science.

A criticism of those sciences applied to human beings is their lack of personalisation. The object studied is the human body devoid of a personality - or a soul. Science borrows more from analytic philosophy than it does from continental philosophy. In its inclusion of human experience, continental philosophy may have something to offer a science of the whole human being - the whole person.