Question

Provide a list of all structures that glomerular filtrate will pass through from the time it leaves the bloodstream in the glomerular capsule to the time it leaves the body. Ensure that your structure list is in order.

Answer 1

Glomerular filtrate will pass from glomerular capillaries to the Bowman's capsule through a filtration barrier named as glomerular membrane. There are mainly three layer present in this glomerular membrane i) capillary endothelium ii)Basement membrane iii)Visceral layer of Bowman's capsule. After leaving this glomerular membrane the glomerular filtrate enters into Bowma's space and then to the renal tubule.

i)Capillary endothelium: This is endothelium layer containing pores of 90 nm in diameter which is permeable to water, solute and small proteins. This endothelium layers helps to transport filtrate molecule to pass from blood capillary to the basement membrane of glomerular membrane.

ii) Basement membrane: This part of the glomerulus membrane consists of three layer, lamina externa, lamina media and lamina interna. This layer helps to pass small molecules having diameter less or equal 8 nm

iii) Bowman's visceral epithelium: This is innermost layer of the Bowman's capsule which consist of layers of podocytes. This podocytes covers the whole basement membrane and are seperated by gaps named filtration slit. This gapsin this layers helps glomerular filtrate to pass in Bowman's space.

Through this structures glomerular filtrate enters into the Bowman's space. From the Bowman's space the filtrate pass into renal tubule for reabsorption, secretion, excretion steps of urine formation. Renal tubule is divide into proximal convoluted tubule, Henle's loop, distal convoluted tubule and Collecting duct.

a)Proximal convoluted tubule: It is the first part of renal tubule. Sodium, glucose reabsorption take place in this part. This part also secretes organic anions, cations and some end products of the metabolism to the filtrate.

b)Henle's loop: This is divided into Thin descending limb of loop of Henle, Thin ascending limb of loop of Henle and thick ascending limb of loop of Henle. This Henle's loop also help in the reabsorption of water, sodium, chloride, potassium ions and ultimately tubular fluid to the distal convoluted tubule.

c)Distal convoluted tubule: In this part sodium and chloride ions are reabsorbed from the tubular fluid by principal cell. After this process the tubular fluid transported to the collecting duct for the final stage of urine formation.

d) Collecting duct: It is the last structure of the nephron or renal tubule. In this part water is absorbed by the action of ADH hormone. After all the reabsorption, secretion the final tubular fluid (Urine) is collected by this collecting duct . The urine from the collecting duct is received by the minor and major calyx of the kidney. The urine then collected in the urinary bladder through ureter. Ultimately when a person sense the urge for urination, the urine from the urinary bladder leaves the body as excretary product.

So the list of all structures that glomerular filtrate will pass through from the time it leaves the bloodstream in the glomerular capsule to the time it leaves the body are as the following order:

1) Capillary endothelium 2) Basement membrane 3) Bowman's visceral epithelium 4) Proximal convoluted tubule 5) henle's loop 6) distal convoluted tubule 7) Collecting duct 8) Minor and Major calyx of kidney 9) Ureter 10) Urinary bladder for storing of urine and ultimately urine leaves the body.