by three layers of supportive tissues namely, renal fascia, perirenal fat capsule and fibrous capsule. Aorta Renal artery Kidney Bladder Urethra Ureter Renal vein Vena cava Figure . Human Excretory System The longitudinal section of kidney (Figure. .
) shows, an outer cortex, inner medulla and pelvis. The medulla is divided into a few conical tissue masses called medullary pyramids or renal pyramids. The part of cortex that extends in between the medullary pyramids is the renal columns of Bertini. The centre of the inner concave surface of the kidney has a notch called the renal hilum, through which ureter, blood vessels and nerves innervate.
Inner to the hilum is a broad funnel shaped space called the renal pelvis with projection called calyces. The renal pelvis is continuous with the ureter once it leaves the hilum. The walls of the calyces, XI Std Biology-Zoology Chapter- %RZPDQ¶V FDSVXOH %RZPDQ¶V FDSVXOH 'LVWDO WXEXOH 'LVWDO WXEXOH &ROOHFWLQJ GXFW D &RUWLFDOQHSKURQ E -X[WDPHGXOODU\QHSKURQ &ROOHFWLQJ GXFW /RRS RIKHQOH /RRS RI +HQOH 3UR[LPDO WXEXOH 3UR[LPDO WXEXOH 5HQDO FRUWH[ 5HQDO PHGXOOD Figure . (a) Cortical nephrons are located predominantly in the outer cortex.
(b) Juxtamedullary nephrons are mainly located in the inner medulla. Efferent arteriole Glomerulus Afferent arteriole Peritubular capillaries Cortex Medulla Vasa recta Figure . Blood Vessels of the Nephron The capillary bed of the nephrons - First capillary bed of the nephron is the glomerulus and the other is the peritubular capillaries. The glomerular capillary bed is different from other capillary beds in that it is supplied by the afferent and drained by the efferent arteriole.
The efferent Efferent arteriole Bowman’s capsule Macula densa Granular cells Afferent arteriole Glomerulus Distal tubule Proximal tubule Loop of henle Collecting duct Figure . Structure of a Nephrons The renal tubule continues further to form the proximal convoluted tubule [PCT] followed by a U-shaped loop of Henle (Henle’s loop) that has a thin descending and a thick ascending limb. The ascending limb continues as a highly coiled tubular region called the distal convoluted tubule [DCT]. The DCT of many nephrons