Excretory Products and their Elimination Test - 1

If a person undergoes prolonged fasting, then his urine will be found to contain higher levels of ketones. Ketones are produced whenever body fat is burned, which often happens in a person on prolonged fasting.

The process in which a substance is transported from the tubular filtrate into the blood in peritubular capillaries is tubular re-absorption. It is called reabsorption both because these substances have already been absorbed once in the intestines and because the body is reclaiming them from a postglomerular fluid stream that is on its way to becoming urine.

Efferent arterioles are smaller in diameter than afferent arterioles. As a result, pressurised blood enters the glomerulus through a relatively wide tube, but is forced to exit through a narrower tube.

In arthropods, the uric acid is excreted by labyrinth. Labyrinth has complex infoldings of its walls and opens directly into bladder.

Metanephros is the functional kidney of snakes. It develops in the fifth week of gestation. It is a permanent kidney.

Maximum reabsorption of calcium occurs in proximal convulated tubule. Around 70% of calcium is reabsorbed here.

Most plasma proteins, blood cells, and platelets are prevented by filtration membrane. Thus, these are not present in the filtrate.

The thin descending limb is passively permeable to both water and small solutes such as sodium chloride and urea. As active reabsorption of solutes from the ascending limb of the loop of Henle increases the concentration of solutes within the interstitial space (space between cells), water and solutes move down their concentration gradients until their concentrations within the descending tubule and the interstitial space have equilibrated. As such, water moves out of the tubular fluid and solutes move in. This means, the tubular fluid becomes steadily more concentrated or hyperosmotic (compared to blood) as it travels down the thin descending limb of the tubule.

In humans, Malpighian body refers to Bowman's capsule and glomerulus. This acts as the basic filtering unit in human kidney.

Kidney does not produce any hydrolytic enzyme. Hydrolytic enzymes are produced by gastrointestinal tract.