Test: Human Excretory System (NCERT) - NEET MCQ

The thick segment of the ascending limb of Henle's loop extends as DCT. Cortical nephrons do not have vasa recta. PCT and DCT are situated in cortex of the kidney. Bowman's capsule encloses the glomerulus.

In the nephron diagram provided:

- A: Represents the glomerulus.
- B: Indicates the Bowman's capsule.
- C: Refers to the proximal convoluted tubule (PCT).
- D: Represents the loop of Henle.
- E: Indicates the distal convoluted tubule (DCT).
- F: Represents the collecting duct.

Therefore, the correct option for the part lateral from A to F in the nephron is C, which corresponds to the proximal convoluted tubule (PCT).

Column-I
(A) Delivers blood to glomerulus
(B) Carries urine to pelvis
(C) Collects filtrate from Bowman's capsule
(D) Loop of Henle
Column-II
(i) Ascending and descending limbs
(ii) Renal artery
(iii) Collecting duct
(iv) PCT
The correct match between Column-I and Column-II is:
A: A-(ii), B-(iii), C-(iv), D-(i)
Explanation:
- The renal artery delivers blood to the glomerulus, which is responsible for filtration. Therefore, the correct match is A-(ii).
- The collecting duct carries urine from the nephron to the pelvis. Hence, the correct match is B-(iii).
- The proximal convoluted tubule (PCT) is responsible for collecting the filtrate from Bowman's capsule. Therefore, the correct match is C-(iv).
- The loop of Henle consists of ascending and descending limbs, involved in the reabsorption of water and ions. Hence, the correct match is D-(i).
Therefore, option A is the correct answer.

The dotted appearance of cortex of kidney is due to the presence of convoluted parts of the tubule (proximal and distal convoluted tubules).

NCERT Topic: Cortex of the kidney

NCERT Line: "The Malpighian corpuscle, PCT and DCT of the nephron are situated in the cortical region of the kidney whereas the loop of Henle dips into the medulla."

A fall in glomerular blood flow/glomerular blood pressure/glomerular filtration rate can activate the jwtaglomerular cells to release renin which regulates the kidney function.

NCERT Topic: Renin release mechanism

NCERT Line: "The JGA plays a complex regulatory role. A fall in glomerular blood flow/glomerular blood pressure/GFR can activate the JG cells to release renin which converts angiotensinogen in blood to angiotensin I and further to angiotensin II."

A nephron is a unit of structure and function in a kidney. Each kidney contains about a million nephrons A nephron is a long tubule differentiated into Bowman's capsule, PCT, loop of Henle and DCT, each part is having its own partiular function. 

NCERT Topic: Nephron

NCERT Line: "Each kidney has nearly one million complex tubular structures called nephrons, which are the functional units."

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

NCERT Topic: Bowman's capsule

NCERT Line: "The epithelial cells of Bowman's capsule called podocytes are arranged in an intricate manner so as to leave some minute spaces called filtration slits or slit pores."

Blood enters glomerulus through afferent arteriole and leaves through efferent arteriole. 

NCERT Topic: Kidney structure

NCERT Line: "Blood from the glomerulus is carried away by an efferent arteriole."

• The liver produces urea as a part of the urea cycle (or ornithine cycle) by converting ammonia, a toxic byproduct of protein metabolism, into a less toxic substance.
• The urea is then transported to the kidneys for excretion in urine.

Protonephridia are primarily concerned with ionic and fluid volume regulation, specifically in osmoregulation. These structures play a crucial role in maintaining the balance of ions and fluids within the organism's body, ensuring proper functioning and health.

NCERT Topic: Protonephridia and osmoregulation

NCERT Line: "Protonephridia are primarily concerned with ionic and fluid volume regulation, i.e., osmoregulation."

Malpighian tubules are the excretory structures responsible for removing nitrogenous wastes and assisting in osmoregulation in insects like cockroaches. These tubules are vital for maintaining the insect's internal balance and overall health.

NCERT Topic: Malpighian tubules

NCERT Line: "Malpighian tubules are the excretory structures of most of the insects including cockroaches. Malpighian tubules help in the removal of nitrogenous wastes and osmoregulation."

The kidneys are situated between the levels of the last thoracic and third lumbar vertebrae, close to the dorsal inner wall of the abdominal cavity. This positioning allows the kidneys to be well-protected within the body while also being easily accessible for their essential functions in filtering waste and maintaining the body's internal environment.

NCERT Topic: Kidney location

NCERT Line: "Kidneys are reddish brown, bean shaped structures situated between the levels of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity."

The primary function of the collecting duct in the kidney is the reabsorption of water. This segment allows for the concentration of urine by reabsorbing large amounts of water, thereby regulating the body's fluid balance. It also plays a crucial role in maintaining the body's pH and ionic balance by selectively secreting hydrogen and potassium ions.

NCERT Topic: Collecting duct

NCERT Line: "Large amounts of water could be reabsorbed from this region to produce a concentrated urine."

The release of Atrial Natriuretic Factor (ANF) causes vasodilation, which refers to the widening or dilation of blood vessels. This dilation leads to a decrease in blood pressure. ANF acts as a counterbalance to the renin-angiotensin mechanism by promoting vasodilation, ultimately helping to regulate blood pressure levels in the body.

NCERT Topic: Atrial Natriuretic Factor (ANF) effects

NCERT Line: "ANF can cause vasodilation (dilation of blood vessels) and thereby decrease the blood pressure."

Sweat glands eliminate substances like NaCl, small amounts of urea, lactic acid, while sebaceous glands eliminate sterols, hydrocarbons, and waxes through their secretions. This process helps in maintaining the skin's health and also provides protective functions. Sweat is primarily involved in cooling the body surface, while sebum from sebaceous glands forms a protective oily covering for the skin.

NCERT Topic: Role of other organs in excretion

NCERT Line: "The sweat and sebaceous glands in the skin can eliminate certain substances through their secretions. Sweat produced by the sweat glands is a watery fluid containing NaCl, small amounts of urea, lactic acid, etc. Sebaceous glands eliminate certain substances like sterols, hydrocarbons and waxes through sebum."