The renal system is also known as the kidney system which is consists of the kidney, ureter, urinary bladder, and urethra, here we will discuss basic things about the kidney so that it will be easy to understand the formation of urine formation so that you could understand the urine analysis and its composition.

Renal system | kidney system

The renal system consists of the part

• Kidney

• Renal artery

• Renal veins

• Ureter

• Urinary bladder

• Urethra

 

Renal system

 

Part of the Renal system and their function

• Kidney: the organ that filter blood plasma

• Renal artery: carry Blood to the kidney

• Renal vein: Blood away from kidney

• Ureter: carry urine kidney to the urinary bladder

• Urinary bladder: storage of urine

• Urethra: way to pass urine

 

 

Part of kidney

Anatomy of kidney

 

• Capsule: Outer  membrane of kidney

• Cortex: Middle membrane

• Medulla: Inner membrane of kidney

• Minor calyx: Moves urine to major calyx

• Major calyx: Moves urine to the ureter

• Hilum: where blood vessels and ureter passes

 

Note

Artery -> arteriole -> capillaries -> vanule -> veins

 

Systems of  blood vessels

Function of kidney

A WET BED

• A: acid-base balance

• W: water balance

• E: Electrolyte balance

• T: Toxin remove

• B: Blood pressure control

• E: Erthroprotien production

• D : D vitamin metabolism

Nephron :

The kidney combines about 1-2 million functional units called nephron and a smaller number of collecting ducts ( length 35-55mm) and nephron also known as a structural unit of the kidney

• Short cortical nephron (80%): a short loop of Henle

• Juxta medullary nephron (20%): a long loop of Henle

Nephron of kidney

Afferent arteriole (wide): that carry blood to glomerular

Efferent arteriole (narrow): that carry away blood from glomerular

Peritubler Capillary: capillaries  that  secretion and absorption the substance

Nephron part

1. Renal capsule

2. Renal tubules

Renal capsule 

• Glomerular: a network of tiny arterial capillary

• Glomerular capsule (bowmen’s capsule): nephron  is closed at one end to form expended cup-shaped structure which encloses glomerular

Renal tubules

• Proximal convoluted tubules (PCT)

• Loop of Henle (medullary loop ) 

• Distill convoluted tubule (DCT) connecting into collecting duct

 

 

Note: 1300 ml of blood enter in kidney per min (30% of cardiac output )

Urine formation: 

this process includes three process

1. Glomerular filtration

2. selective reabsorption

3. tubular secretion 

Glomerular filtration : 

• This filter takes place  because of the difference between the blood pressure in the glomerular (60mmhg)  and the pressure  of the filtrate capsule(15mmhg)

• blood is filtered while passing through glomerular or capillary by a filtration membrane

• Water and Small molecules will pass ( eg plasma)

• Large molecules do not pass ( eg blood cells, proteins)

• Only ⅕ of plasma filter here

• Filter flued is called glomerular filtration and the volume of filtrate formed by both kidneys each minute is glomerular filtration rate

Normal GFR rate : 125ml/min or 180 liter /day

Selective reabsorption : 

• Most reabsorption absorption back to peritubular capillary through the tubules occurs in PCT (eg water, electrolyte, and glucose.)

• 60-70 % of filtrate reach the medullary loop (loop of hanle ) where absorption of sodium and chloride occurs

• 15-20% of filtrate reach in DCT (the eg more electrolytic substance of sodium)

• Filter enter in the collecting duct where water reabsorbed

Notes: transport maximum( renal threshold): kidney maximum capacity of absorption of a substance

Tubular secretion:

the substance is not required and foreign material(eg drug) initially filtered out of the blood by peritubular capillary into tubules

• Potassium in PCT, DCT, collecting duct

• Ammonia in PCT

• H+ in PCT, DCT

• URIA  in loop of hanle

kidney / renal disease could be identified by urine analysis  click here to check urine analysis