KIDNEYS:
Shape and size are reddish brown, bean shaped structures situated between the levels of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity. Each kidney of an adult human measures 10 to 12 cm in length 5 to 7 cm in width, 2 to 3 cm in thickness with an average weight of 122-170 grams.
LEFT KIDNEY IS LITTLE HIGHER THAN THE RIGHT ONE BECAUSE OF MORE SPACE BEEN OCCUPIED BY THE LIVER ON RIGHT SIDE. SO, ONLY IN HUMAN BEINGS THE RIGHT KIDNEY SLIGHTLY BELOW THE LEFT. BUT IN OTHER ANIMALS, EXAMPLE RABBIT, THE LEFT KIDNEY IS BELOW THE RIGHT.
KIDNEY is covered by three protective layers which are as follows:
1.Renal capsule:It is innermost, tough protective cover made up of white fibrous connective tissue, with elastic fibres and few muscles.
2.Adipose capsule:It is the middle cover involving adipose tissue and act as shock absorber.
3.Renal fascia: It is outer most fibrous covering linking it with the event abdominal wall.
INTERNAL STRUCTURE:
Inner to the helum is a broad funnel shaped called the renal pelvis with the projections called calyces. The outer layer of kidney is a tough capsule. Inside the kidney, there are two zones, and outer cortex and inner medula. The medula is divided into few conical masses projecting into the calyces. The cortex extend in between the medullary pyramids as a renal columns call columns of bertini.JUXTAGLOMERULAR APPARATUS (JGA):
The epithelial cell of the distal convoluted tubule that come in contact with afferent and efferent arteriols are more dense than the other tubular cell and are collectively called the macula densa. Along side the macula densa, the wall of afferent arteriole contains modified smooth muscle fibres called juxtaglomerular cell(JG cell). Together with Macular densa, they constitute the juxtaglomerular apparatus(JGA). Juxtaglomerular cells release renin in which helps in regulation of blood pressure and glomerular filtration rate(GFR).
Each renal pyramid has a broad base to word the cortical side. Apex is pointed and is called renal papilla. 1-3 renal papillae project into a cavity wall minor calyx,which join up and form major calyces. Interstitial fluid of medula region has a higher osmotic concentration equal to some 1200 mOsm/L. Due to higher quantity of to salutes , NaCl and urea. Cortical region close to medulla is called juxtamedullary area. The major calyces open into a broad funnel shaped structure called renal pelvis place inner to hilum. It is lined by transitional epithelium. It lead into ureter.
NEPHRON
NEPHRON IS THE STRUCTURAL AND FUNCTIONAL UNIT OF KIDNEY.
MALPIGHIAN BODY: Glomerulus along with bowman's capsule is called malpighian body.
0 Comments