Excretory Products and their Elimination Test - 11

The glomerulus is a tuft of capillaries

• Blood enters the glomerulus through the afferent arteriole, a fine branch of the renal artery.
• Blood from the glomerulus is carried away by an efferent arteriole.

Option A: Urea moves to blood get filtered and eliminated with water in urine via kidneys.

Option B: Uric acid is the least toxic form because it is insoluble in water as there are in solid form, thus, contains the least water.
In birds, uric acid mixes with undigested food to form the bird dropping.

Option C: Ammonia is very toxic and needs water for diffusion.

Option D: Carbon dioxide excretion takes place through the lungs.

Hence Option B is correct.

During micturition, parasympathetic stimulation causes the detrusor muscle to contract and the internal urethral sphincter to relax.

The external urethral sphincter (sphincter urethrae) is under somatic control and is consciously relaxed during micturition. 

Renal corpuscle, also called malpighian body, filtration unit of vertebrate nephrons, functional units of the kidney.
It consists of a knot of capillaries (glomerulus) surrounded by a double-walled capsule (Bowman’s capsule) that opens into a tubule.

The pH of urine under healthy conditions is slightly less than 7 so, slightly acidic in nature.

Urochrome is the yellow pigment responsible for the characteristics of urine color.
It is produced by the breakdown of red blood cells in the liver.

Renal pyramids, also known as malpighian pyramids, are kidney tissues that are shaped like cones.

Around 7 to 18 pyramids exist in the innermost part of the kidney, which is called the renal medulla.
In humans, there are usually only seven of the pyramids.

Glomerular filtrate contains glucose, inorganic salts and creatinine but it do not contain globulins protein.

The process of release of urine is called micturition and the neural mechanism causing it is called the micturition reflex.

I. Infants and toddlers can not control this reflex action, thus micturition is an involuntary action for them.

II. Adults and grown-up children can control the reflex process of micturition voluntarily to some extent.

Hence, both statements are correct.

Snakes, crocodiles, and birds don't urinate, urea and other water soluble stuff are pushed out with the faeces.

Unlike mammals, birds, snakes and crocodiles mix both liquid waste and solid waste into the semi-solid paste. Thus, they do not possess a urinary bladder.

Hence option A is correct.

The epithelial cells of Bowman’s capsule called podocytes, which are arranged in an intricate manner so as to leave some minute spaces called filtration slits or slit pores.

Lungs help in excretion of carbon dioxide
Liver help in excretion of toxic substance
Skin help in removal of extra salts along with sweat.

Hence, option C is correct.

Ascending limb of Henle’s is not permeable to water.
The descending limb is although permeable to water. 

Conditional reabsorption of sodium ions and water takes place in distal convoluted tubule (DCT).

Urea cycles operates in liver, where ammonia is converted into urea. Sometimes urea cycle also occurs in kidney.

The nephron is the structural and functional unit of the kidney. The body of the nephron is divided into renal corpuscle, PCT, Henle's loop and DCT.which perform vital functions such as filtration, reabsorption, and secretion. Nephron along with collecting ducts are called as uriniferous tubules. Hence Vital morphological and physiological units of the mammalian kidney are Uriniferous tubules'.

FF = Filtration fraction,
RPF = Renal plasma flow,
GFR = Glomerular filtration rate = 125ml (for healthy human),

FF = GFR/RPF,
So, FF% = GFR/RPF ×100
= 125/600 ×100
= 125/6
=20.83%

I. Avian kidneys have very short loops of Henle.
Loops of Henle are used in a concentration of urine.
II. Birds make urine highly hypotonic.

Hence, Statement I is correct and II is wrong.

The adult human kidney is metanephric, the third and final excretory organ that develops in a vertebrate embryo.

First embryonic tubules formed in vertebrates during embryonic development are pronephric.

During urine formation, the tubular cells secrete substances like hydrogen ions, potassium ions and ammonia into the filtrate.