Renal Pathophysiology
Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed in MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Which of the following is CORRECT regarding the nephron?The glomerulus is about 20 μm in diameter and is formed by the invagination of a tuft of capillaries into the dilated, open end of the nephron (Bowman’s capsule).Functionally, the glomerular basement membrane permits the free passage of neutral substances upto 4 nm in diameter and totally excludes those with diameters greater than 8 nm.In the distal convoluted tubule, while the predominant principle cells (P) are involved in acid secretion and HCO3− transport, the intercalated cells (I) are associated with Na+ reabsorption and vasopressin-stimulated water reabsorption.The renin-secreting juxtaglomerular cells are situated in that part of the thick ascending limb of the loop of Henle, which traverses close to the afferent arteriole from which the tubule arose.In a resting adult, the kidneys receive about 450 mL of blood per minute.
Renal, Cardiovascular, and Pulmonary Functions of Dopamine
Nira Ben-Jonathan in Dopamine, 2020
The adult human kidney contains 0.8–1.5 million nephrons, each of which constitute the basic structural and functional unit of the kidney. Figure 7.2 shows the structure of a single nephron. A nephron is composed of a corpuscle, located in the kidney cortex, which specializes in filtration, and a long tubule, which winds through the medulla and specializes in reabsorption and secretion. The corpuscle is the initial filtration unit of the nephron and is composed of a capillary tuft, the glomerulus, which is enclosed within the Bowman’s capsule. The glomerulus receives blood supply from an afferent arteriole with a wider diameter than the efferent artery. This narrowing facilitates the generation of hydrostatic pressure as a driving force for efficient filtration of the blood. Podocytes within the Bowman’s capsule wrap around the capillaries and carry out the filtration process. The filtrate then moves into the tubule, where it is further processed by sequential reabsorption and secretion steps along the length of tubule, as described below.
Nanoparticles in Cancer Treatment: Types and Preparation Methods
Hala Gali-Muhtasib, Racha Chouaib in Nanoparticle Drug Delivery Systems for Cancer Treatment, 2020
In healthy tissues, nanoparticles are removed from circulation by the glomerular filtration system or by the mononuclear phagocyte system (MPS) [4, 5]. The glomerular filtration system is located in the nephrons of the kidneys and uses hydrostatic pressure to filter waste products from the blood. The MPS is part of the immune system and its main function is to remove pathogens from blood circulation; the MPS is composed of macrophages and monocytes located in reticular connective tissues. The primary mechanism of nanoparticle removal in the MPS is through endocytosis [6]. There is a size dependent correlation between nanoparticle size and their interaction with macrophages; in liposomes, nanoparticles smaller than 100 nm are removed at a slower rate from the blood in comparison to bigger nanoparticles [6]. In addition, a negative surface charge has been associated with rapid removal from the blood in comparison to neutral charges. One common way to address this issue is to graph a polymer coat (i.e., polyethylene glycol, phosphatidylinositol and phosphatidylserine) onto nanoparticles to protect them from immune recognition.
The anti-hypertensive effects of sodium-glucose cotransporter-2 inhibitors
Published in Expert Review of Cardiovascular Therapy, 2023
Luxcia Kugathasan, Lisa Dubrofsky, Andrew Advani, David Z.I. Cherney
Under normal physiological conditions, blocking sodium transport in the proximal tubule increases distal tubular load and promotes a compensatory enhancement of sodium, chloride, and potassium reabsorption at the loop of Henle primarily by Na-K-2Cl (NKCC2) cotransporters. However, owing to the natriuretic-diuretic coupling effect of SGLT2 inhibition at the proximal tubule, it has been postulated that a diluted load with a low chloride concentration is delivered to the distal nephron and renders tubular reabsorption at the loop of Henle ineffective (Figure 3) [96]. Specifically, since the proximal tubule is highly permeable to water and SGLT2 inhibition renders glucose non-resorbable, isotonicity between the tubular fluid and blood is maintained by osmoregulation. The resulting diuresis is thought to decrease the chloride ion concentration in the proximal tubular filtrate [92]. Therefore, it is speculated that the requirement of two chloride ions for each cotransport at the thick ascending limb subsequently reduces NKCC2 cotransporter activity in a diluted chloride environment [92,96]. The off-target impact of SGLT2 inhibitors at the thick ascending limb may indicate similar activity to that of a loop diuretic to promote plasma volume contraction, although this effect has yet to be proven [96].
Renal and Hepatic Disease: Cnidoscolus aconitifolius as Diet Therapy Proposal for Prevention and Treatment
Published in Journal of the American College of Nutrition, 2021
Maria Lilibeth Manzanilla Valdez, Maira Rubi Segura Campos
In order to eliminate toxins, it is necessary to excrete metabolites, this process is done by nephrons. The kidney has around one million nephrons, inside them there is the glomerulus (a blood vessel and capillaries) that connects with the tubules and then collects the urine and transports it to the bladder (17). It is important to mention that although there are many nephrons, they cannot be regenerate. Therefore, once a nephron suffers a damage (due to progress of some pathology) this nephron will be lost, due to the above it is important to take care of the kidneys, due to the danger of developing chronic diseases. In Figure 1, the structure of the kidney is presented, through the renal vein it reaches the blood with metabolism products such as urea, creatinine, uric acid, products of the metabolism of hemoglobin and the metabolites of various hormones. These products are eliminated in the urine through the ureter, an excess of urea and uric acid has negative consequences in the organism, it can cause systemic toxicity. Once filtered and without toxins, blood returns to the organism through the renal artery (15).
Advances in understanding vertebrate nephrogenesis
Published in Tissue Barriers, 2020
Joseph M. Chambers, Rebecca A. Wingert
Following IM specification, the progression of vertebrate renal development involves the stepwise generation and degeneration of several kidney forms: the pronephros, mesonephros, and metanephros. Each kidney iteration develops along the anterior-posterior embryonic axis, where each subsequent version becomes more structurally complex than the previous structure. The pronephros emerges first, and while it is vestigial/nonfunctional in mammals, it is functional in other vertebrates such as fish and frogs.23 The mesonephros is further developed and partially functional in mammals, while serving as the final kidney form in amphibians and fish.24 However, the fully formed and functional version of this vital organ in mammals is the metanephros, which develops through branching morphogenesis events that result in an arborized structure essential for fluid homeostasis. Importantly, all three vertebrate kidney forms share the overall structure of the kidney’s functional unit: the nephron. Broadly, the nephron is composed of a blood filter, a segmented tubule, and a collecting duct system to shuttle urine to the bladder.
Related Knowledge Centers
- Kidney
- Renal Corpuscle
- Capillary
- Glomerulus
- Bowman'S Capsule
- Epithelium
- Lumen
- Endothelium
- Basement Membrane
- Podocyte