A nephron is the kidney’s basic functional and structural unit, undertaking the regulation of water and soluble substances in the body. It filters blood, reabsorbs critical components, and excretes the rest, ultimately ensuring that urine leaves the body in the correct concentration. A nephron constitutes a renal tubule and corpuscle, with the latter consisting of a tuft of capillaries known as glomerulus, which are encircled by a sac called the Bowman’s capsule. The renal corpuscle is the filtration unit, while the tubules are dedicated to reabsorption and excretion (Breshears & Confer, 2017). The glomerulus filters fluids and solutes from the blood as it passes through the capillary walls’ endothelial cells, the basement film, and the podocytes that line up the capsule. The formed filtrate flows down into the renal tubule, where water and other necessary substances are reabsorbed or added to the solution. Excess components are excreted as urine, effectively modulating the body’s fluid volumes and soluble elements.
The kidneys undertake various critical homeostatic functions, including fluid-electrolyte balance, and blood-base balance, among others. Hypanatremia, an electrolyte imbalance, denotes the unregulated rise in serum sodium concentration in the blood. The hyperosmolar condition is caused by a reduction in the total body water in relation to the electrolyte content, which exceeds the normal range of between 135 and 145 nmol/L (Gao et al., 2017). According to Neal et al. (2018), nephron functionality is dependent on the glomerular perfusion, which fluctuates to ensure the correct hydrostatic pressure to achieve the right physiological flows and pressures in the tubule. An increase in sodium level in the blood triggers an adaptive response through which the endocrine system secrets hormones to reduce the reabsorption of sodium and increase the glomerular capillary coefficient (Hall, 2016). The reaction increases the level of sodium excreted through urine, expands the kidney’s water conservation capacity, and significantly reduces sodium reabsorption into the body, effectively restoring the optimal balance.
Conclusively, the nephron is the kidneys’ basic structural and functional unit, compromising the renal corpuscle and the renal tubule. The corpuscle consists of tufts of capillaries known as glomerulus, encased in a Bowman’s capsule. The glomerulus is the filtration unit, while the tubule is the tube through which the filtered liquid flows for excretion or reabsorption into the body. A sodium imbalance triggers a series of reactions, which minimizes its reabsorption and an increase in the kidney’s water retention.
References
Breshears, M. A., & Confer, A. W. (2017). The urinary system. Pathologic Basis of Veterinary Disease, 617–681.
Gao, S., Cui, X., Wang, X., Burg, M. B., & Dmitrieva, N. I. (2017). Cross-sectional positive association of serum lipids and blood pressure with serum sodium within the normal reference range of 135–145 mmol/L. Arteriosclerosis, Thrombosis, and Vascular Biology, 37(3), 598-606.
Hall, J. E. (2016). Kidney dysfunction mediates salt-induced increases in blood pressure. Circulation, 133(9), 894–906. Web.
Neal, C. R., Arkill, K. P., Bell, J. S., Betteridge, K. B., Bates, D. O., Winlove, C. P., Salmon, A. H. J., & Harper, S. J. (2018). Novel hemodynamic structures in the human glomerulus. American Journal of Physiology-Renal Physiology, 315(5), F1370–F1384.