Structure of the kidney and nephron

physiology

1. Structure of the kidney and nephron Dr. Maria idrees; PT

2. kidney There is a depression on the medial border of kidney called hilum , through which renal artery, renal veins, nerves and ureter pass.

3. DIFFERENT LAYERS OF KIDNEY Components of kidney are arranged in three layers: 1. Outer cortex 2. Inner medulla 3. Renal sinus.

4. 1. Outer Cortex Cortex is dark and granular in appearance. It contains renal corpuscles and convoluted tubules. At intervals, cortical tissue penetrates medulla in the form of columns, which are called renal columns or columns of Bertini .

5. 2. Inner Medulla Medulla contains tubular and vascular structures arranged in parallel radial lines. Medullary mass is divided into 8 to 18 medullary pyramids. Broad base of each pyramid is in contact with cortex and the apex projects into minor calyx.

6. 3. Renal Sinus Renal sinus consists of the following structures: i . Upper expanded part of ureter called renal pelvis ii. Subdivisions of pelvis: 2 or 3 major calyces and about 8 minor calyces iii. Branches of nerves, arteries and tributaries of veins iv. Loose connective tissues and fat.

7. Nephron Functional and structural unit of the kidney Approximately 1 million nephrons /kidney Each nephron has two components Vascular component Tubular component

8. Nephron (Tubular component)

9. Hollow, fluid-filled tube single layer of epithelial cells Components Bowman’s capsule Proximal convoluted tubule Loop of Henle Descending limb (thin) Ascending limb (thin and thick part) Distal convoluted tubule Collecting duct or tubule Juxtaglomerular apparatus

10. Bowman’s capsule – expanded double walled invagination that cups around the glomerulus to collect fluid from the glomerular capillaries. From bowman’s capsule, filtered fluid passes into PCT. From PCT, fluid passes into loop of Henle [LH].

11. Nephron (Vascular component) Dominant part is the glomerulus Glomerulus is a tuft of glomerular capillaries . large amounts of fluid & solutes are filtered from the blood.

12. Vascular Component Renal Artery enters the kidney and forms afferent arteriole, which supplies each nephron . Afferent arteriole delivers blood to the glomerulus . Glomerular capillaries rejoin to form another arteriole – the efferent arteriole. The blood that was not filtered in the glomerulus goes to efferent arteriole.

13. Efferent arteriole gives second set of capillaries, the peritubular capillaries, which supply the renal tissue and are important in exchange with tubular system. ( Peritubular means around the tubular system) Peritubular capillaries rejoin to form venules , that drain in renal vein.

14. Nephron Two types of nephrons Distinguished by location and length of their structures Juxtamedullary nephrons Cortical neohron