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In Remembrance
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Join Date: Sep 2006
Location: about 45 minutes to anywhere!
Posts: 3,086
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In Remembrance
Join Date: Sep 2006
Location: about 45 minutes to anywhere!
Posts: 3,086
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good question rev?
what the kidneys do
An organ involved with the elimination of water and waste products from the body. In vertebrates the kidneys are paired organs located close to the spine dorsally in the body cavity. They consist of a number of smaller functional units called urinary tubules or nephrons. The nephrons open to large ducts, the collecting ducts, which open into a ureter. The two ureters run backward to open into the cloaca or into a urinary bladder. In mammals, the kidneys are bean-shaped and found between the thorax and the pelvis. The number, structure, and function of the nephrons vary with evolution and, in certain significant ways, with the adaptation of the animals to their various habitats.
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the world of the body
The kidneys are situated on each side of the vertebral column, at the level of the last (twelfth) rib. Each kidney is about 12 cm long and weighs about 150 g — about the size of a fist. Despite their small size, the two kidneys receive an enormous blood flow — about 1.2 litres/min in an adult — which is a quarter of the total output of the heart (5 litres/min).
One of the main functions of the kidneys is the removal from the body (excretion) of waste products such as urea, uric acid, and creatinine. However, the kidneys' role is not merely excretion. They are also regulatory organs, controlling the volume and the composition of the body fluids and maintaining the correct osmolality, ion concentrations, and acid-base status of the body.
Each kidney is bean-shaped, with a slit opening — termed the hilus — through which pass the renal artery and vein, the renal nerves and lymphatics, and the ureter, which connects the kidney to the bladder (Fig. 1). A tough connective tissue capsule covers the outer layer of the kidney, the cortex. The deeper part of the kidney, the medulla, consists of a number (6-18) of conical pyramids, the tips of which (papillae) project into the funnel-shaped urine collectors — the renal calyxes (calices) — which merge to form the funnel-shaped upper end of the ureter — the renal pelvis. (Renal, pertaining to the kidney, from its Latin name, ren.)
The nephron is the functional unit of the kidney. (Nephros is the Greek for kidney.) Each kidney has about one million nephrons, and the total length of the nephrons in the body is about 100 miles!
The nephron begins as a Bowman's capsule — the blind end of the nephron — invaginated by a knot of capillaries, the glomerulus (glomerular capillaries). A Bowman's capsule and its glomerular capillaries are together termed a renal corpuscle. Sir William Bowman, British surgeon and histologist, described this in 1842.
The rest of the nephron consists of the proximal convoluted tubule, proximal straight tubule, loop of Henle, and distal convoluted tubule. The distal tubules join to form collecting tubules which in turn join to form collecting ducts, which open at the tip of the renal papilla (Fig. 2).
The Bowman's capsules, proximal tubules, and distal tubules are situated in the renal cortex, whereas the loops of Henle and the collecting ducts extend down through the medulla.
http://www.answers.com/kidneys?cat=h...&ver=2.3.0.609
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with much love,
lou_lou
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by
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, on Flickr
pd documentary - part 2 and 3
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Resolve to be tender with the young, compassionate with the aged, sympathetic with the striving, and tolerant with the weak and the wrong. Sometime in your life you will have been all of these.
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