Tag: excretory system of human

The renal pelvis or pelvis of the kidney is the funnel-like dilated part of the ureter in the kidney. In humans, the renal pelvis is the point where the two or three major calyces join together. Renal pelvis, enlarged upper end of the ureter, the tube through which urine flows from the kidney to the urinary bladder.

A malphagian body is constituted of two parts - Glomerulus and Bowman's capsule. The glomerulus is the tuft of capillaries and has the filtering apparatus. The Bowman's capsule has a cup-like sack present at the beginning of the tubular component of a nephron.

Juxtamedullary nephrons form about $15%$ of total nephrons. Their glomeruli are found in the inner margin of the cortex. They control plasma volume when water supply is short. 

Cortical nephrons either have short or absent loops of Henle. Only juxtamedullary nephrons have long loops of Henle, which plunge into the renal medulla and create a hypersomotic interstitium via counter current multiplication. 

Nephron is the structural and functional unit of the kidney. Juxtamedullary nephrons are found only in birds and mammals. These are juxtamedullary on the basis of their Loop of Henle which is deep in the renal medulla and the renal corpuscle is in the medulla and only around 15-20% of the nephrons are juxtamedullary.

The excretory organs of insects are malpighian tubules. They collect water and uric acid from surrounding haemolymph (blood) and empty it into the gut.

Blood plasma contains red and white blood cells, blood proteins, glucose, water, nitrogenous wastes, salt. Glomerular filtrate contains glucose, salt, water, nitrogenous wastes. Blood cells and plasma proteins are not filtered through the glomerular capillaries because they are relatively larger in size.

The proximal tubule can only reabsorb a limited amount of glucose. When the blood glucose level exceeds about 160-180 mg/dl or 160-180 mg/100ml, the proximal tubule becomes overwhelmed and begins to excrete glucose in the urine. this point is called the renal threshold of glucose (RTG).
So, the correct answer is option B.

A glomerulus is a network of capillaries responsible for the filtration of blood in the nephron the functional unit of the kidney. The glomerulus is surrounded by a single layer of epithelium called the Bowman's capsule constitute a renal corpuscle, the basic filtration unit of the kidney. 

The filtration slits present in the endothelium of the glomerulus are of the size 25 nm that can allow the plasma and solutes to diffuse in but not the blood cells. So the filtrate in the Bowman's Capsule that has diffused in from the glomerulus is colourless due to an absence of RBCs.