Rheology
Perhaps the greatest limitation to any concept of health comes from an unseen state: the flow characteristics of blood in vital tissues. In the limbs, obstructions soon show up as pain and other inflammatory signs, but those in deeper structures will do so only in hindsight, and the longer the flow of lifetime, the greater the potential for perturbations in the river bed ahead and the accumulation of impedance in vessel walls. When blood ceases to flow, time ceases to flow.
At the other end of life, without a clear flow of blood, the blastocyst could not have been implanted. Flow depends upon the smoothness of an unbroken vessel wall and is characterised by the proteins, solutes and cellular constituents of blood as it courses along. Almost certainly, a diet rich in the many nutraceutical compounds from plants90 will maintain vessel integrity, but probably only upon a state afforded by a fortunate early life, relieved of a chronic infectious and inflammatory load. If medicine and culture would only direct their resources into the care and protection of pre–conceptual, pregnant and nursing mothers, good health would attend without the need for much medication, herbal or otherwise, and many of the discussions in this book would be glad to be rendered redundant.
Patterns and drivers
Mindedness is developed from micro to macro, from the binary choices facing the cell to the dense skein of S–O–R loops that constitute the multicellular organism (to be revisited in Section 22). Yet it is the macro, by the tidal forces generated by the sun, moon and earth, that generates the micro. As discussed in Section 3, the nervous system provides immediate responsiveness, mostly musculoskeletal while the endocrine system enables capacitance. A neurotransmitter is effectively paracrine: a local hormone, delivered as it were by a pipette, so the distinction is more of degree than kind.
Even though ultradian rhythms like heart-rate and blood pressure respond inherently to demand, as walking briskly upstairs will demonstrate, they do so against an inherent rhythmicity in heart cells, and there appears to be a background circadian influence on patterns of this cardiovascular reactivity.
The coupling of these circadian drives and their organisation within the human body can be systematised into the following four regional elements (all of which are underpinned by the flow characteristics of the blood):
1. The Hypothalamic–Pituitary Driver
2. Cholinergic and Aminergic referees/regulators
3. Hypothalamic–Posterior Pituitary Intensifiers
4. Organ responders and pacemakers.
1. The hypothalamic–pituitary driver
The pituitary stalk leads to five cell types in the order of the usual number of secretory cells:
1. Somatotrophes mainly secreting Growth Hormone
2. Lactotrophes secreting Prolactin
3. Gonadotrophes secreting FSH and LH
4. Corticotrophes mainly secreting ACTH
5. Thyrotrophes secreting TSH.
It seems that the relative populations of each cell type can vary to accommodate changes in environmental patterns and that there are even cells within the pituitary that behave like stem cells, conferring great adaptive capacity. This correlates well with the horizontal relationship between hormonal axes that is fundamental to Endobiogenic theory, though it falls short of substantiating the theory of the double loop (see footnote 48).
The diurnal patterns within the endocrine system are well known and documented, notably in thyroid and adrenal axes in which cortisol figures strongly. These phases of dominance divide the light/dark cycle into a series of time–segments, as follows:
| Hour | Phases of hormonal feedback loops | Phase length |
| 22 | cortisol* decreases to its lowest value and remains low | for 6 hours |
| 22– | maximal influence of insulin–like growth factors but with an obligate dependent on sleep states, for next 6 hours | |
| 3 | pacemakers in the liver increase amplitude in preparation for next phase | 1 hour |
| 4 | cortisol* abruptly released and rises steeply (most births and deaths occur here) | 4 hours |
| 8 | cortisol peaks and its rise flattens off | |
| 8 | levels* of thyroid hormones rise steeply | 3 hours |
| 11 | thyroid hormones peak and their rise flattens off | |
| 14–16 | trough in levels* of thyroid hormones | 2 hours |
| 16–18 | steep pre–crepuscular rise* in cortisol and thyroid hormones; peak in body temperature | 2 hours |
| 18–20 | slow and modest crepuscular ascent | 2 hours |
| 20–22 | descent of cortisol* | 2 hours |
| *I am using the single hormone as shorthand to stand in for the axis within which it operates. Although these hormones can be measured in blood, they stand not for themselves alone but for a web of relations and so it would be more accurate to characterise these as modifications of feedback loop sensitivity in the axes (induced in part by other co–factors, such as ADH) rather than serum levels of the hormones themselves, but the outcome is effectively the same. Even the whole axis operates in tandem with others so that endocrine life is always coaxial. More crucially and impossible to measure directly, hormonal levels exist in proportion to the population of their receptors on the membranes and in the cytosol of responsive cells. |
As can be seen from the table above, these phases are not symmetrical either side of noon, and unpredictable events must inevitably modify these episodic fluctuations in the daily rhythm. Social and cultural events tend to follow a normative pattern that respects local conditions and the diurnal phases. As everybody connected to a theatrical production, at least in the Western tradition knows, a matinée performance is very different from the one given a few hours later. Although we do not allocate function rigidly to a time of day, cultural timings are far from arbitrary. A fixed rhythm must be stable and short enough to provide a regular background. There could be many candidates for pulses that might influence human attentiveness and stamina and surely they vary between individuals. Pulses are not simply of arithmetic length but are complex waveforms that are stable yet available for recalibration according to circumstances.
Even so, the question for physiology is whether any of these phases is divisible into shorter rhythms. The question for health asks whether a greater responsiveness to episodic time would confer benefit. The first rather obvious observation notes that the phases are of different length and range from one or two to five or six hours (but see the caveat in the preceding paragraph). For circadian rhythms to be effective for survival and reproduction, they need a range of values that allows for the opposite needs of precision and approximation, allowing for the capacity to anticipate with a responsiveness to variation. In humans, attention and focus depend upon personal and cultural motives and expectations and cannot be generalised even though recent research has tried to explore the range which finds values as short as eight seconds while there seems to be some convergence on maxima of 20 minutes. This is the approximate length of time taken for each cell division during embryogenesis and has much the same period as the pulse generated by the discharge of CRH from the hypothalamus to the pituitary, and possibly also that of Gn–RH. Regular rhythmic pulsation thus drives the adrenal and reproductive axes in human metabolism. Even if such regularities do exist, cultural divisions of time do not seem to follow them, taking other cues and markers. Nevertheless, lectures and talks on a single theme rarely exceed the hour without exciting comment or protest.
Even if this short period is real, circumstance easily extends it as enforced waiting has an effect on human performance and expectation. Those who are used to episodic work will recognise