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Locations of secretion and reabsorption in the nephron
In renal physiology, reabsorption or tubular reabsorption is the process by which the nephron removes water and solutes from the tubular fluid (pre-urine) and returns them to the circulating blood.[1] It is called reabsorption (and not absorption) because these substances have already been absorbed once (particularly in the intestines) and the body is reclaiming them from a postglomerular fluid stream that is on its way to becoming urine (that is, they will soon be lost to the urine unless they are reabsorbed from the tubule into the peritubular capillaries. This happens as a result of sodium transport from the lumen into the blood by the Na+/K+ATPase in the basolateral membrane of the epithelial cells. Thus, the glomerular filtrate becomes more concentrated, which is one of the steps in forming urine. Nephrons are divided into five segments, with different segments responsible for reabsorbing different substances.[2] Reabsorption allows many useful solutes (primarily glucose and amino acids), salts and water that have passed through Bowman's capsule, to return to the circulation. These solutes are reabsorbed isotonically, in that the osmotic potential of the fluid leaving the proximal convoluted tubule is the same as that of the initial glomerular filtrate. However, glucose, amino acids, inorganic phosphate, and some other solutes are reabsorbed via secondary active transport through cotransport channels driven by the sodium gradient.
Renin–angiotensin system:
The kidneys sense low blood pressure.
Release renin into the blood.
Renin causes production of angiotensin I.
Angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II.
Angiotensin II stimulates the release of aldosterone, ADH, and thirst.
Aldosterone causes kidneys to reabsorb sodium; ADH increases the uptake of water.
Water follows sodium.
As blood volume increases, pressure also increases.
^Skirving, Mya; Borger, Pam; Chiovtti, Tony; Duncan, Jacinta; Gerdtz, Wayne; Guay, Patrick-Jean; Martin, Genevieve; Walker, Katrina; Woolnough, Jim; Wright, Jane (2020). "Chapter 11: Regulation of Water, Salts and Gases". In Attley, Teresa; Irwin, Kirstie (eds.). Biology WA ATAR Units 3&4 (1st ed.). South Melbourne, Victoria, Australia: Cengage Learning Australia. pp. 374, 402. ISBN 9780170452922.
In renal physiology, reabsorption or tubular reabsorption is the process by which the nephron removes water and solutes from the tubular fluid (pre-urine)...
surrounded by capillaries. The major functions of these lining cells are the reabsorption of water and small molecules from the filtrate into the blood, and the...
Renal reabsorption of sodium (Na+) is a part of renal physiology. It uses Na-H antiport, Na-glucose symport, sodium ion channels (minor). It is stimulated...
is the nephron. It processes the blood supplied to it via filtration, reabsorption, secretion and excretion; the consequence of those processes is the production...
Selective reabsorption is the process whereby certain molecules (e.g. ions, glucose and amino acids), after being filtered out of the capillaries along...
(salt) and water. This is large in comparison to normal renal sodium reabsorption which leaves only about 0.4% of filtered sodium in the urine. Loop diuretics...
Renal glucose reabsorption is the part of kidney (renal) physiology that deals with the retrieval of filtered glucose, preventing it from disappearing...
filtrate (the result of which is to convert blood to urine) are filtration, reabsorption, secretion and excretion. Filtration or ultrafiltration occurs in the...
Enterohepatic circulation is the circulation of biliary acids, bilirubin, drugs or other substances from the liver to the bile, followed by entry into...
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is...
collecting duct participates in electrolyte and fluid balance through reabsorption and excretion, processes regulated by the hormones aldosterone and vasopressin...
Renal reabsorption of chloride (Cl−) is a part of renal physiology, in order not to lose too much chloride in the urine. Walter F., PhD. Boron (2005)....
Reuptake is the reabsorption of a neurotransmitter by a neurotransmitter transporter located along the plasma membrane of an axon terminal (i.e., the pre-synaptic...
Renal protein reabsorption is the part of renal physiology that deals with the retrieval of filtered proteins, preventing them from disappearing from the...
Renal oligopeptide reabsorption is the part of renal physiology that deals with the retrieval of filtered oligopeptides, preventing them from disappearing...
surrounded by capillaries. The major functions of these lining cells are the reabsorption of water and small molecules from the filtrate into the blood, and the...
distal tubules and collecting ducts of the nephron. It influences the reabsorption of sodium and excretion of potassium (from and into the tubular fluids...
collecting ducts of the nephron and increases reabsorption of sodium from the glomerular filtrate. Reabsorption of sodium results in retention of water, which...
for water reabsorption. Through unknown mechanisms, activation of the sympathetic nervous system leads to enhanced proximal tubular reabsorption of salt...
hormone aldosterone. Aldosterone increases sodium reabsorption. Sodium and chloride (salt) reabsorption is also mediated by a group of kinases called WNK...
for more Na+ reabsorption, which may cause a transient increase in fluid reabsorption as well. However, within a few days, Na+ reabsorption returns to normal...
potassium are most widely used in conjunction with diuretics that block reabsorption of sodium and water upstream from the distal tubule (thiazides and loop...
Na+/K+-ATPase in the basolateral membrane of the epithelial cells. Sodium reabsorption is primarily driven by this P-type ATPase – 60–70% of the filtered sodium...
functioning fluid) is modified into secondary urine through selective reabsorption by the cells lining the metanephridium. The saccate metanephridia are...
force for reabsorption from the lumen. Thiazides are also thought to increase the reabsorption of Ca2+ by a mechanism involving the reabsorption of sodium...
The basic physiologic mechanisms of handling fluid and electrolytes by the nephron - filtration, secretion, reabsorption, and excretion - are labelled....
syndrome. Loss of function of this reabsorption system results in decreased sodium, potassium, and chloride reabsorption in the thick ascending limb, as...
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