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The structure and function of the epithelial cells lining the lumen change during the course of the nephron, and have segments named by their location and which reflects their different functions. Fig.4) Diagram outlining movement of ions in nephron, with the collecting ducts on the right.
Each adult human kidney contains around 1 million nephrons, while a mouse kidney contains only about 12,500 nephrons. The kidneys also carry out functions independent of the nephrons. For example, they convert a precursor of vitamin D to its active form, calcitriol; and synthesize the hormones erythropoietin and renin.
The body is very sensitive to its pH. Outside the range of pH that is compatible with life, proteins are denatured and digested, enzymes lose their ability to function, and the body is unable to sustain itself. The kidneys maintain acid-base homeostasis by regulating the pH of the blood plasma. Gains and losses of acid and base must be balanced.
The kidney has many functions, which a well-functioning kidney realizes by filtering blood in a process known as glomerular filtration. A major measure of kidney function is the glomerular filtration rate (GFR). The glomerular filtration rate is the flow rate of filtered fluid through the kidney.
The main difference between the pronephros and the mesonephros is that the pronephros consists of non-integrated nephrons with external glomeruli. [7] The most complex nephrons are found in the metanephros of birds and mammals. [19] [21] [22] The kidneys of birds and mammals have nephrons with loop of Henle. [23]
The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra.The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH.
In mice, the kidneys are approximately 1 cm (0.4 in) long, weighing 400 mg, with 16,000 nephrons, while in the killer whale, the kidney length exceeds 25 cm (10 in), the mass is approximately 4.5 kg (10 lb), with the number of nephrons of the order of 10,000,000. At the same time, the killer whale kidneys are reniculate, with each renicule ...
The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis.The collecting duct participates in electrolyte and fluid balance through reabsorption and excretion, processes regulated by the hormones aldosterone and vasopressin (antidiuretic hormone).