Excretory Products and their Elimination Test - 4

Ascending limb of Henle’s is not permeable to water. The descending limb is although permeable to water. Counter current exchange takes place between the loop of Henle’s and arteries surrounding it.

Each nephron consists Bowman’s cup, tubules and loops of Henle’s. filtration of blood occurs in glomerulus cells present in Bowman’s cup. Some materials are added to initial filtrate in distal convoluted tubule.

The diagram shown above is Malpighian body or renal corpuscles. The marked part in this is called Podocytes or visceral epithelial cells in Bowman’s capsule in the kidney that warp around capillaries of the glomerules.

adult human kidney is metanephric, the third and final excretory organ that develops in a vertebrate embryo. First embryonic tubules formed in vertebrates during embryonic development are pronephric.

Towards the centre of the innerconcave surface of the kidney is a notchcalled hilum through which ureter, bloodvessels and nerves enter. Inner to the hilumis a broad funnel shaped space called therenal pelvis with projections called calyces. The medulla is divided into a few conical masses projecting into the calyces. Thus, 7, 9, and 10 are pelvis, hilum and calyx respectively.

Nephrons are the physical unit or functional unit of kidney. Millions of nephrons are present in each kidney but physiological unit of kidney is urinigerous tubule.

Renal corpuscle, also called malpighian body, filtration unit of vertebrate nephrons, functional units of the kidney. It consists of a knot of capillaries (glomerulus) surrounded by a double-walled capsule (Bowman's capsule) that opens into a tubule

The blood plasma is filtered through the capillaries of the glomerulus into the capsule. The Bowman's capsule empties the filtrate into the proximal tubule that is also part of the duct system of the nephron. A glomerulus receives its blood supply from an afferent arteriole of the renal circulation

Urinary bladder is absent in snake and bird because the urine of these is semi-solid consisting mainly of uric acid. The primary function of urinary bladder is to store urine in mammals. The urinary bladder cannot store semi-solid urine.

The urinary bladder is a hollow elastic organ that functions as the body's urine storage tank. Urine produced by the kidneys flows through the ureters to the urinary bladder, where is it stored before passing into the urethra and exiting the body.

On the medial margin of the kidney is concave region called the renal hilum. The renal hilum is the entrance to the renal sinus. Structures such as the renal veins, artery, nerves and lymphatic vessels are located in the renal hilum.

Inside the kidney, there are two zones, an outer cortex and an inner medulla. The cortex extends in between the medullary pyramids as renal columns called columns of Bertini.

The efferent arteriole emerging from the glomerulus forms a fine capillary network around the renal tubule called the peritubular capillaries.

A minute vessel of this network runs parallel to the Henle’s loop forming a ‘U’ shaped vasa recta. Vasa recta is absent or highly reduced in cortical nephrons.

Homeostasis is the maintenance of constant body temperature. It is mainly maintained by excretion and osmoregulation, which is the function of kidney.

The excretory system in human consistsof a pair of kidneys, one pair of ureters, aurinary bladder and a urethra. Kidneys are reddish brown, bean shaped structures situated between the levels of last thoracic and third lumbarvertebra close to the dorsal inner wall of the abdominal cavity.