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Examples of substances reabsorbed are solute-free water, sodium, bicarbonate, glucose, and amino acids. Examples of substances secreted are hydrogen, ammonium, potassium and uric acid. The nephron is the structural and functional unit of the kidney. Each adult human kidney contains around 1 million nephrons, while a mouse kidney contains only ...
A countercurrent system in the renal medulla provides the mechanism for generating a hypertonic interstitium, which allows the recovery of solute-free water from within the nephron and returning it to the venous vasculature when appropriate. Some diseases of the nephron predominantly affect either the glomeruli or the tubules.
Diagram of the circulation related to a single glomerulus, associated tubule, and collecting system The renal corpuscle in the cortex (outer layer) of the kidney. At the top, the renal corpuscle containing the glomerulus. The filtered blood exits into the renal tubule as filtrate, at right. At left, blood flows from the afferent arteriole (red ...
The nephron is composed of a renal corpuscle and a renal tubule. The renal corpuscle is a blood-filtering part of the nephron and is located in the cortex. The renal tubule extends from the renal corpuscle to the medulla into the loop of Henle and then returns back to the cortex. Finally, the renal tubule flows with its distal end into its ...
The blood exiting the efferent arterioles of these nephrons enter the vasa recta, which are straight capillary branches that deliver blood to the renal medulla. These vasa recta run adjacent to the descending and ascending loop of Henle and participate in the maintenance of the medullary countercurrent exchange system.
The urinary system is under influence of the circulatory system, nervous system, and endocrine system. Aldosterone plays a central role in regulating blood pressure through its effects on the kidney. It acts on the distal tubules and collecting ducts of the nephron and increases reabsorption of sodium from the glomerular filtrate.
Each nephron begins in a renal corpuscle, which is composed of a glomerulus enclosed in a Bowman's capsule. Cells, proteins, and other large molecules are filtered out of the glomerulus by a process of ultrafiltration , leaving an ultrafiltrate that resembles plasma (except that the ultrafiltrate has negligible plasma proteins ) to enter Bowman ...
The larger arteries throughout the brain supply blood to smaller capillaries. These smallest of blood vessels in the brain, are lined with cells joined by tight junctions and so fluids do not seep in or leak out to the same degree as they do in other capillaries; this creates the blood–brain barrier. [44]