Reflection-7

Dr. Azad’s clinic. The boys are seated across from Dr. Azad, the chapter freshly read and annotated. They begin their discussion.

Kabir: This chapter was on the physiology of fluid balance. And this time it is not Charaka who speaks, but Sushruta.

Dr. Azad: It has to be Sushruta because he was the one to use an imagery of pot to describe the process of urine formation.

Aarav: But Dr. Azad, is this entire narration authentic to the Sushruta Saṃhitā? It feels more elaborate, almost as though things have been added.

Dr. Azad: A very perceptive question. The Ayurvedic concepts you just read — about kleda, sāra and kiṭṭa, the role of the vāyus, the connection between urine and sweat, and the tint of urine from pitta — are all genuine and consistent with the classical texts. However, the mysterious author is not quoting Sushruta verbatim. Instead, he has woven together explanations found across different authorities, Charaka, Sushruta, and Vāgbhaṭa, to create a more comprehensive, consolidated picture. Suśruta was the one who used the imagery of pots and emphasized the relation between urine and sweat. Charaka, by contrast, explained different fluid entities and then treated them all as functionally similar, calling them udaka. Vāgbhaṭa, writing later, harmonized both perspectives into a unified system.

Rohan: So it’s like a composite lesson? Not Sushruta’s words alone, but a careful blending?

Dr. Azad: Exactly. You can think of it as a pedagogical synthesis. The mysterious author here seems to have combined their perspectives into one flowing dialogue for students to grasp the whole system more clearly.

Aarav: Sushruta’s description of urine formation using the analogy of the mud pot was imaginative and informative. But I have to ask, is there any basis for this idea of fluids seeping gradually into the bladder through unseen channels?

Dr. Azad: Your skepticism is well-placed, Aarav. The model described in this chapter is not anatomically accurate by modern standards. There are no direct channels from the gut to the bladder. Instead, as you know, urine is formed in the kidneys via glomerular filtration, followed by tubular reabsorption and secretion. Constituents of urine too are not similar to those of gut.

Aarav: Then what is Sushruta trying to prove?

Dr. Azad: We must understand what Sushruta was trying to do. He was building a theory based on observed effects, not microscopic anatomy, which was inaccessible to him, and this is important.

Kabir: So when he says urine is collected “not by pouring but by seepage,” using the mud pot as a metaphor, it’s really just an analogy to explain gradual accumulation?

Dr. Azad: Precisely. It is not a physiological description in the modern sense. It is a conceptual model, drawn from everyday observation: how water slowly travels across the walls of the pot, or how urine output changes with hydration. These metaphors were tools for teaching patterns, not physical pathways.

Rohan: Still, Sushruta talks about these channels as though they’re real anatomical structures. Isn’t that misleading?

Dr. Azad: From our perspective today, yes. But in his time, these were proposed structures. They were not seen through dissection but were postulated based on what could be observed: urine output, changes in sweat, signs of dehydration. It is a faulty proposition, no doubt, but not an irrational one. It tried to make sense of systemic fluid regulation using the language and logic available then.

Aarav: Did ancient Ayurveda scholars know about kidneys? What functions did they ascribe to them?

Dr. Azad: Yes, they knew about kidneys. They called them Vrikka. But the kind of dissection techniques they followed did not possibly allow them to recognise the connection between kidneys and urinary bladder. Hence, they thought kidneys regulated fat metabolism, as they must have seen thick fat deposits around them. In reality, kidneys do not have any major role in fat metabolism.

Aarav: Is it possible that they saw ureters and could not identify them correctly?

Dr. Azad: Yes, it is possible that Sushruta or his students actually saw the ureters, but mistook them for other tubular structures like blood vessels or lymphatic channels. Even today, surgeons sometimes confuse ureters with arteries during operations. This shows how difficult it would have been, without magnification or modern methods, to correctly identify their function.

Kabir: Ah, that is interesting. But you said kidneys do not have any ‘major role’ in fat metabolism. Do they have any minor role?

Dr. Azad: In a limited way, yes. Kidney cells, especially in the tubules, use fatty acid breakdown for their own energy and also handle cholesterol and lipoproteins. When this process goes wrong, fat can accumulate and damage the kidney. But these are modern insights, and the resemblance to the old Ayurvedic claim is only coincidental. The ancients must have seen fat around the kidneys and must have assumed regulation, while in reality the kidney’s link with fat is only indirect.

Aarav: Earlier in the chapter Sushruta spoke about Kloma near the heart. Was that really the lung?

Dr. Azad: That is a very old controversy. Some teachers identified Kloma as the right lung, while others described it as something distinct. The lungs themselves were certainly recognised, but their exact physiology was unclear. Since the right lung differs slightly from the left in shape, many commentators believed this difference justified giving it a separate name, Kloma. At the same time, Kloma was linked to thirst regulation, possibly because moisture was seen in the breath.

Kabir: Do lungs play any role in fluid balance in reality?

Dr. Azad: Yes, in modern terms the lungs do contribute to fluid balance. They humidify the air we breathe out, and in disease they can either accumulate fluid or lose it excessively. But the sensation of thirst is regulated by the hypothalamus, not by the lungs. So what you read in the lesson reflects the ancient uncertainty: the organ was known, yet its function and identity were debated.

Aarav: The part where he explains how sweating reduces urine output, that actually sounds intuitive. Isn’t that consistent with what we now know?

Dr. Azad: Yes, it is completely consistent with what we see today.

Rohan: But how does the body actually do that? What tells the kidneys to hold back water when we sweat too much?

Dr. Azad: An important question. Today we know that hormones coordinate this regulation. The hypothalamus senses when the body is losing water and signals the release of antidiuretic hormone, or ADH, from the pituitary gland. ADH then directs the kidneys to reabsorb more water, so less is lost in urine. Aldosterone, another hormone from the adrenal glands, helps adjust the balance of sodium and water. Together they act as the body’s water regulators, shifting fluid conservation or release depending on circumstances. What Sushruta described as “coordination of channels,” we now explain as hormonal control of fluid balance.

Aarav: So even though he didn’t know about ADH or aldosterone, he still noticed that the body shifts fluids from one route to another?

Dr. Azad: Yes, and that is a valuable point. In both cases he presents, the man with Atisāra (diarrhoea) and the patient who sweated excessively, we see the same core observation: when the body loses fluid one way, it reduces it in other ways. This matches what we understand today about compensatory homeostatic mechanisms. So the inference that the body allocates fluid resources across different routes is actually quite accurate in principle.

Kabir: But what about the clinical conditions depicted here? Do they correspond to similar conditions as understood now?

Dr. Azad: In modern terms, the man with diarrhoea clearly has traveller’s diarrhoea with dehydration. The frequent watery stools deplete both water and electrolytes, which is why his urine output is so low. What Sushruta explained as the bladder being “deprived” corresponds to prerenal oliguria caused by fluid loss.

Kabir: And what about the treatments he prescribed? Do they work?

Dr. Azad: The right treatment is to restore fluids and electrolytes, which is exactly what Sushruta has suggested. This mysterious author has cleverly integrated modern understanding into Ayurveda by mentioning the sweet-salty water. Ayurveda itself also prescribes frequent sipping of light fluids such as pānaka, maṇḍa, or saktu, which achieve a similar purpose of fluid replenishment, though not precisely the same as today’s oral rehydration therapy. And Kutajārīṣṭa, a fermented preparation, has a further role. Kutaja bark contains alkaloids, including compounds like conessine, which reduce intestinal motility. In Ayurveda, this was described as grāhī (binding action). Modern science interprets it as slowing diarrhoea and allowing fluids to be absorbed.

Rohan: What about the second case? What would this be diagnosed today?

Dr. Azad: This second man shows features of heat exhaustion due to excessive induced sweating. The thirst, dizziness, and lack of urine are classic signs of volume depletion. In modern medicine, the management is cooling the body to prevent further fluid loss and giving oral rehydration. What Sushruta described with his pot analogy — refilling the larger pot and closing the channel of sweat — is essentially rehydration and preventing ongoing losses. The observation is clinically accurate, though explained in metaphorical terms.

Kabir: Uncle, does the fermented nature of Arishta also help? You had prescribed Amritāriṣṭa last time when I had viral fever.

Dr. Azad: Exactly. Fermented preparations can replenish gut microbial flora disrupted by diarrhoea. Sushruta did not know about microbes, but his formulation had benefits that we can now explain.

Aarav: Does this fluid balance have to do with Prāṇa, Apāna, and Samāna Vāyu, as discussed in the previous chapter?

Dr. Azad: Yes. In Ayurvedic reasoning, this coordination of inputs and outputs was linked to the Vāyus. Prāṇa guided intake, Apāna directed elimination, and Samāna mediated the transformative balance between them. Samāna Vāyu was also described as controlling the movement of water and the regulation of sweating, ensuring that what enters, what is transformed, and what is expelled remain in harmony. In that sense, fluid regulation, digestion, and waste disposal were viewed as one continuous system.

Aarav: But he attributes the yellow color of urine to pitta mixing into it, and connects that to the colour in jaundice. Is there any truth in that?

Dr. Azad: There is a kernel of truth. In jaundice, urine darkens due to elevated bilirubin, a yellow pigment derived from hemoglobin breakdown. Pitta, in Ayurvedic theory, is closely associated with bile and is described as yellowish. So, while pitta in its broader sense is not a physical substance in the biochemical sense, the correlation between bile metabolism and urine colour was correctly observed. They noticed the association, even if the underlying cause was not known. Pitta being the mala of Rakta can be seen as an early imagination of bilirubin as a byproduct of hemoglobin. The normal yellow colour of urine, however, is due to urobilin, not bilirubin. Referring to white stools in Kāmala corresponds to what we now call obstructive jaundice, which was thus correctly recognised and clinically diagnosed in Ayurveda.  

Rohan: And the idea that “urine is waste excreted after retaining the Sāra” how would you interpret that today?

Dr. Azad: Sushruta thought urine as a waste product formed after digestion in the gut. The nutrient past was absorbed, and waste was removed. It was a simplistic model.

Kabir: So overall, would you say this was good science for its time, even if it’s biologically wrong?

Dr. Azad: Yes, that is a fair conclusion. These were sincere, systematic attempts to make physiological sense of the body using patient observation, analogy, and logical inference. They lacked microscopes, chemical assays, or renal histology. But they were not making random guesses. They used structured reasoning and empirical observation, which are foundational to scientific thinking. Their conclusions may be outdated, but their methods of inference, within those constraints, were rigorous.

Aarav: That gives me a new appreciation for these texts. They’re not just medical myths. They’re historical windows into the logic of early medicine.

Dr. Azad: Exactly. The mistake would be to treat these models as literal truths today. But the right way to read them is as intellectual efforts to grasp complex processes with limited tools. They represent early stages of systems thinking. And in that sense, they deserve our respect, even if we also recognize their limits.

[The discussion trails off into thoughtful silence as the boys reflect on how observation, analogy, and reasoning, even without instruments, once laid the groundwork for understanding the body.]

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