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10

(source: free.fr) Alain Bombard He is a french biologist who voluntarily tested how many days a man can survive drinking seawater and how? Biologist point of view Sea contains ~3.5% of salt$^1$. Our kidney separates the waste from water and excrete them in urine provided the salt content is less than ~2%.$^2$ So, it will take the water already present ...


8

The comment of the poster to my request for clarification cites “The formation of ammonia itself requires… large quantities of water to dilute it out of a biological system” I conclude that he assumes that the problem with animals eliminating ammonia as such is one of solubility in water. This is not the case. The solubility of ammonia is such that saturated ...


7

There are actually very few situations where organs can be harvested from donors. For all deceased donor transplants, the donor must be confirmed as being brain dead (both brain stem and higher cortical functions). However, in order for the organs to remain viable they must not become ischaemic - which is obviously a huge problem when the patients heart has ...


6

The urogenital system as a cohesive functional unit probably evolved very early in vertebrate history. Hagfishes and lampreys have separate systems for reproduction and excretion. More derived groups of fishes use kidney tubules and ducts for sperm delivery outside the body (Helfman et al. 2009). The vertebrate nephron may be homologous to the invertebrate ...


6

The answer to this question is quite simply this: The activation energy for the uncatalysed reaction is such that the amount of decomposition of urea in aqueous solution at blood temperature and pH is negligible in the time taken for the transfer of urea to the kidney. The literature supporting this is very old, so I shall first cite a relatively ...


5

It is to do with the extend of the damage to the glomerulus. In nephrotic syndromes the glomerulus is damaged so that there is death of the podocytes. This happens to sufficiently high number of podocytes so that large proteins such as albumin and clotting factors can leak out causing large proteinuria. Damage to the basement membrane may also occur, such as ...


5

[Partial answer] [OP claim:] Urea in water can decompose into ammonia which is toxic. Probably not as easily as you think. If Wikipedia is correct: Urea alone is very stable due to the resonance forms it can adopt. Some bacteria use urease to catalyze the reaction by 14 orders of magnitude (says Wikipedia). There are some primary sources from the ...


4

ANF (Atrial Natriuretic Factor more commonly known as ANP - atrial natriuretic peptide) squeezes (vasoconstricts) the efferent arteriole. This means the pressure in the glomerulus is higher (like if you squeeze the end of a hose) and so more fluid is squeezed out i.e. the glomerular filtration rate (GFR) is higher. It also dilates the afferent which means ...


4

I don't know that one is treated as more critical than the other. Both are potentially life-threatening conditions. One in five people over 40 will develop heart failure (HF). That makes it a very common disease of aging, and as more people survive other events (e.g. MI), it will continue to be prevalent, if not to rise.[1][2] When a patient presents with ...


4

Have a look at this figure (from here): In the descending loop the NaCl concentration is lower than in the surrounding tissue which leads to a passive water transport along the gradient, which leads to a concentration effect. In the ascending loop then NaCl is actively transported out of the loop which then prevents the diffusion of water back into the loop....


4

Short answer The ammonia resultant from the protein metabolism is toxic to the body and specially kidney. (William V. et al.) Long answer Protein is a poly-peptide composed by amino acids. Each amino acid has an amine group (-NH2) in its composition. In the metabolism of the amino acids, this amine group is taken, and if it isn't needed is released the to ...


3

Short answer There is not likely to be a single mechanism involved, but the study authors suggest that high chloride is the main issue; they refer to previous work showing a whole variety of issues that can be caused by higher-than-normal chloride levels. Although saline contains roughly the same sodium content as blood plasma, it contains a lot more ...


3

Non-opsonized particles (Particles that can't be coated with opsonins like antibodies or complement proteins) can be engulfed by macrophages which could end up, for example, in the lung secretions and be coughed up one day. Note that a cell can only engulf a particle so large, so you'll not feel yourself coughing up anything out of the ordinary. Only tiny ...


3

The article itself1 defines what the authors mean by both proteinuria and refractory: ...progressive proteinuria, with [urine protein-to-creatinine] values ranging from 0.6 at initial evaluation to 5.16 at highest (reference interval, <0.2), despite medical intervention with increasing doses of benazepril HCl (0.5-1.02 mg/kg PO q12h) and control of ...


3

Proteinuria is the presence of proteins in urine. Refractory means "persistent" or "stubborn", but in medical terms it means resistant to treatment or cure.


2

After drinking 1 liter of seawater with 3.5% salt your kidneys need to excrete at least 1.5 liters of urine in order to maintain normal blood sodium levels, which leaves you with 0.5 liter of negative water balance. This occurs because the kidneys have a limited ability to concentrate urine; it's explained in more detail here. When a negative water balance ...


2

First of all, I can't understand how can you regard an electrochemical process (tubular secretion) as chemical substance (hormone). Tubular secretion is the transfer of materials from peritubular capillaries to renal tubular lumen. Tubular secretion is caused mainly by active transport. Usually only a few substances are secreted. These substances are ...


2

It appears that the invagination of the renal kidney is vestigial from development and unlike human and other mammals, the bovine kidney does not form a smooth outer cortex. The kidneys of the bovine do not lose their foetal lobulation. -Renal Anatomy - Anatomy & Physiology en.wikivet.net However this is not related to its function. Despite what ...


2

There is one study that I can find that has been cited in the medical literature that examines individuals taking valerian extract for generalized anxiety disorder. In this paper, there do not appear to be any claims that valerian has any diuretic or anti-diuretic properties. However, that's not to say that those properties don't exist. Additionally, there ...


2

I am putting here the main points from the link given by @WYSIWYG (i.e. this): High glucose levels reduce the levels of the powerful vasodilator nitric oxide in blood vessels, a shortfall that increases the risk of high blood pressure and eventually narrows down the vessels...increased modification of proteins by a glucose-derived molecule is a player in ...


2

There are metanephric diseases, which refer to the location of pathologic tissue relative to the main kidney mass, but unless someone with more expertise wants to weigh in, I don't think that kidneys themselves are called metanephric. There is also a developmental stage of the kidneys, in which they are referred to as metanephros. Perhaps you're thinking ...


2

Extracellular acid base homeostasis in human physiology is maintained primarily by the bicarbonate buffer, as regulated by both the kidneys and the lungs (and to a certain extent, the intracellular phosphate buffer). Outside of illness or injury, (arterial) blood pH is kept between 7.35 and 7.45. There is an excellent review of acid base homeostasis in ...


2

No. Lungs are a feature of tetrapods (land vertebrates) and some lungfish. Many fish have swim bladders, which are thought to be homologous to lungs (they evolved from the same ancestral structure) but are not lungs, and I don't think they come in pairs anyway. Some other air-breathing organisms evolved air-breathing structures that also get called "...


2

The water doesn't get drained. As blood flows down a vas rectum, in any given section of the arteriole the tonicity is slightly higher outside the arteriole vs inside the arteriole. This results in a small amount of water flowing out of the arteriole to attempt to equilibrate the osmolarity. But before this has even finished happening, the blood has ...


1

The definition of GFR given in Wikipedia - Glomerular filtration rate (GFR) is the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman's capsule per unit time. Since it is difficult to measure the volume entering into each Bowman's capsule, as a proxy, we measure the clearance of a solute that we know isn't going to ...


1

Are you talking about Sodium Polystyrene Sulphonate (a.k.a SPS)? If yes, then ... Quoting from Chaitman, Dixit and Bridgeman (2016) Synthetic cation-exchange resins are insoluble polymers resembling a crystalline lattice. When placed in a solvent, this structure swells, allowing the exchange of ions between the reactive group on the resin (in the ...


1

In the glomerulus of the nephron we have filtration occuring. The subsequent formation of an ultra-filtrate travels down the tubulus from Bowmans space; during this journey, the filtrate will be exposed to various transporters and forces such as solvent drags and diffusion gradients, which leads to the (re)absorption of this filtrate. Reabsorption occurs ...


1

The Natural Medicines Database monograph for Valerian includes a pooled adverse effects analysis of more than 20 clinical trials with Valerian for various indications. No diuretic effects were identified in any trials. Natural Medicines Database monographs are available by subscription only and are considered by the vast majority of healthcare ...


1

Countercurrent multiplication What is flowing in the opposite direction to the glomerular filtrate for it to be called "counter-current"? The filtrate is moving in the opposite direction of the filtrate. It's a loop. Filtrate moves in two directions relative to the nephron, down (from the cortex toward the papilla/through the medulla) and up (...


1

Why reabsorb $NH_4^+$ in the thick ascending limb if you're just going secrete it in the collecting duct This is an excellent question. When you find an odd, seemingly inefficient aspect of physiology, it's an opportunity to learn something new. This alternating secretion, reabsorption, and secretion starts to make sense when you look at the anatomy of the ...


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