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The renal cortex is the outer portion of the kidney between the renal capsule and the renal medulla. [1] In the adult, it forms a continuous smooth outer zone with a number of projections ( cortical columns ) that extend down between the pyramids .
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 .
The cortex and medulla of the kidney contain nephrons, [21] each of which consists of a glomerulus and a complex tubular system. [22] The cortex contains glomeruli and is responsible for filtering the blood. [7] The medulla is responsible for urine concentration [23] and contains tubules with short and long loops of Henle. [24]
Turtles and some lizards have urinary bladder [50] that opens into the cloaca [54] but snakes and crocodiles do not have it. [50] Compared with the metanephros of birds and mammals, the metanephros of reptiles is simpler in structure. [21] Unlike mammals, the kidneys of reptiles do not have a clear distinction between cortex and medulla. [43]
The renal columns, Bertin columns, or columns of Bertin, a.k.a. columns of Bertini are extensions of the renal cortex in between the renal pyramids. They allow the cortex to be better anchored. (Cortical extensions into the medullary space.) Each column consists of lines of blood vessels and urinary tubes and a fibrous material.
The kidney's ability to perform many of its functions depends on the three fundamental functions of filtration, reabsorption, and secretion, whose sum is called renal clearance or renal excretion. That is: Urinary excretion rate = Filtration rate – Reabsorption rate + Secretion rate [1]
When renal blood flow is reduced (indicating hypotension) or there is a decrease in sodium or chloride ion concentration, the macula densa of the distal tubule releases prostaglandins (mainly PGI2 and PGE2) and nitric oxide, which cause the juxtaglomerular cells lining the afferent arterioles to release renin, activating the renin–angiotensin–aldosterone system, to increase blood pressure ...
The renal lobe is a portion of a kidney consisting of a renal pyramid and the renal cortex above it. [1] In humans, on average there are 7 to 18 renal lobes. [medical citation needed] It is visible without a microscope, though it is easier to see in humans than in other animals.