Anatomy of kidney
Anatomical position
The kidney is situated inside the abdominal cavity near
posterior abdominal wall about 2.5 cm away from the mid line that is vertebral
column. The right kidney is slightly lower than the left kidney because of the presence
of liver on the right side. It extents from tip of the 9th costal
cartilage upto lower margin of the 3rd lumber vertebra. This area is
called renal fossa. The kidney is a retroperitoneal structure that is its
situated behind the peritoneum just above the kidney very important endocrine
gland called as adrenal or suprarenal gland.
Size
It is about 4cm X 6cm X 9cm in average adult person.
Shape
It is describe as bean shaped.
Colour
Brown in colour
Weight
250 to 500 gm
Blood Supply
It is supplied by renal artery branched of abdominal aorta.
About 1.5 liter of blood is supped to the kidney per minute.
If there is damage to the renal artery in the form of narrowing or blocked due
to thromboembolism. The disease of renal artery may cause kidney failure and
secondary renal hypertension. The blood comes out by vein which goes to
inferior vena cava (IVC)
External covering and relation
The kidney is courted by perinephric fat and renal capsule.
The radical border of kidney is concave called as pelvis of kidney. Lateral
border is convex, if you divided the kidney into two halves. It is divided into
2 parts, the internal 1/3 is called as medulla and out 2/3rd is
called as cortex.
Microscopic
If we study the section of the kidney under the microscope
then we will find that the kidney made up of nephrons. There are 1 million nephrons
in each kidney. Nephron is the structural and functional unit of the kidney.
Microscopic structure
Microscopically the nephron has following parts
1. Clomerulus
2. Bowman’s Capsule
3. Proximal convoluted tubule (PCT)
4. Loop of Henle (LH)
5. Distal convoluted tubule
6. Collecting dust/tubule
The renal artery after entering kidney substance divides
into millions of capillaries and form network of capillaries inside the kidney
substance. All the parts of nephron and the capillaries are single cell layered
thick therefore, perfusion and diffusion.
The glomerulus is made up of afferent and effect capillary. The
DCT goes up and passes near the glomerulus and Bowman’s capsule and is continuous
further as a collecting duct. The part of DCT near glomerulus is having
specialized cells called juxtaglomerular apparatus.
This part produces a substance called as renin, which is immediately converted
into angiotensin I and II which regulates the blood pressure. The collecting
duct from different nephron joint to form bigger ducts which produces duct of Bellini
this group of ducts of Bellini opens into pyramids. This pyramids open into miner
calyx. 3-4 miner calyces joint to produce major calyces. All major calyces
opens into pelvis of kidney.
Function of kidney
1.
Formation of urine
2. Excretion of waste toxic products like urea, creatinine, etc.
3. Regulation of water balance.
4. Regulation of electrolyte balance.
5. Regulation of pH of the blood.
6. Regulation of blood pressure.
7. It helps the process of erythropoiesis by producing substance erythropoietin.
2. Excretion of waste toxic products like urea, creatinine, etc.
3. Regulation of water balance.
4. Regulation of electrolyte balance.
5. Regulation of pH of the blood.
6. Regulation of blood pressure.
7. It helps the process of erythropoiesis by producing substance erythropoietin.
Normal Composition of Urine
Normal adult person the total urine output in 24 hours is
1.5 liter to 3 liter depending upon the fluid intake and the environmental
conditions. The urine is mainly composed of following substance.
1.
Water which constituents 90% to 95%.
2.
Urea the remaining solid part contains urea,
creatinine, sodium, potassium, chloride, small quantity of hormones.
3.
Bile pigment – Urobilinogen, urobilin which is
responsible for pale yellow colour urine some time urine may contain some drugs
which the patient has consumed.
When abnormal substances appear in the urine that indicates
the presence of some disease. The abnormal substance which may be present in
case of diseases are:
1.
Proteins
2. Glucose
3. Ketones
4. Bilirubin
5. Bile salt
6. Cells like
7. Casts
8. Crystals
2. Glucose
3. Ketones
4. Bilirubin
5. Bile salt
6. Cells like
7. Casts
8. Crystals