Human excretory system Questions in English

(B) In humans,the right kidney is located slightly lower than the left kidney. This asymmetry is primarily due to the presence of the large right lobe of the liver,which occupies a significant portion of the upper right quadrant of the abdominal cavity,pushing the right kidney downwards.

(D) The correct answer is $D$. The renal vein carries blood away from the kidneys after the process of filtration.
Since the kidneys are responsible for filtering urea out of the blood to form urine,the blood exiting the kidneys via the renal vein contains the lowest concentration of urea compared to other major veins in the body.

(A) The kidneys receive a significant portion of the cardiac output to facilitate the filtration of blood and the formation of urine.
On average,the kidneys receive approximately $20-25\%$ of the total cardiac output (the volume of blood pumped by the heart per minute).
This high rate of blood flow is essential for the effective removal of metabolic wastes and the regulation of body fluid composition.

(B) The renal columns of Bertini are extensions of the renal cortex that project into the renal medulla between the renal pyramids. These columns contain blood vessels and connective tissue,serving as a structural support for the kidney.

(D) The correct answer is $D$.
Nephrons are the structural and functional units of the kidney.
Each human kidney contains approximately $1$ million $(10^6)$ nephrons.

(C) The Malpighian corpuscle (also known as the renal corpuscle) is the initial blood-filtering component of a nephron.
It consists of two main structures: the glomerulus (a network of capillaries) and the Bowman's capsule (a cup-like sac that surrounds the glomerulus).
Therefore,Bowman's capsule and glomerulus together constitute the Malpighian corpuscle.

(A) The Loop of Henle is a $U$-shaped portion of the tubule that conducts urine within each nephron of the kidney.
It plays a critical role in the concentration of urine through the counter-current mechanism.
Since it is a structural component of the nephron,it is an integral part of the excretory system.

(C) The kidneys are reddish-brown,bean-shaped structures situated between the levels of the last thoracic $(12^{th})$ and third lumbar $(3^{rd})$ vertebrae,close to the dorsal inner wall of the abdominal cavity.
Therefore,the correct anatomical position of the kidneys is between the $12^{th}$ thoracic and $3^{rd}$ lumbar vertebrae.

(D) The kidneys in humans are of the $Metanephros$ type.
During embryonic development,the kidney develops from the posterior part of the nephrogenic cord,known as the $Metanephros$.
$Pronephros$ is the most primitive type found in cyclostomes and embryonic stages of some vertebrates.
$Mesonephros$ is found in adult fishes and amphibians.
$Metanephros$ is the advanced type found in reptiles,birds,and mammals,which is characterized by the presence of a permanent kidney.

(A) The inner wall of the $Bowman's$ capsule is lined by specialized cells known as $Podocytes$.
These cells are arranged in an intricate manner so as to leave some minute spaces called filtration slits or slit pores.
$Podocytes$ wrap around the glomerular capillaries and play a crucial role in the process of ultrafiltration of blood.

(C) The mammalian kidney is divided into an outer cortex and an inner medulla.
$1$. The renal cortex contains the Malpighian corpuscles,proximal convoluted tubules $(PCT)$,and distal convoluted tubules $(DCT)$.
$2$. The loop of Henle,collecting tubules,and the ducts of Bellini are primarily located in the renal medulla.
Therefore,the correct option is $C$.

(D) The human kidney is a metanephric kidney.
In the human kidney,the nephrons are organized such that the glomeruli are located in the renal cortex,while the loops of Henle extend into the renal medulla.
Therefore,the statement that glomeruli are concentrated in the cortex is correct.

(D) The $Uriniferous$ $tubule$ (or $Nephron$) is the structural and functional unit of the kidney.
It consists of two main parts: the $Glomerulus$ and the $Renal$ $tubule$.
The $Renal$ $tubule$ further consists of the $Bowman's$ $capsule$,$Proximal$ $Convoluted$ $Tubule$ $(PCT)$,$Loop$ of $Henle$,and $Distal$ $Convoluted$ $Tubule$ $(DCT)$.
Therefore,the $Loop$ of $Henle$ is a component of the $Uriniferous$ $tubule$.

(B) In mammals,including the rabbit,the urinary bladder stores urine temporarily. The urine is then transported out of the body through a tube called the urethra. Therefore,the urinary bladder opens into the urethra.

(A) The Bowman's capsule is a cup-shaped,double-walled structure that forms the beginning of the nephron (uriniferous tubule).
It encloses the glomerulus,which is a tuft of capillaries.
Together,the Bowman's capsule and the glomerulus form the Malpighian body or renal corpuscle.
Its primary function is the ultrafiltration of blood,where water,salts,glucose,and nitrogenous wastes are filtered from the blood into the lumen of the nephron.

(C) The correct answer is $C$.
The kidney is divided into two main regions: the outer renal cortex and the inner renal medulla.
The glomeruli,along with the Bowman's capsule (together forming the renal corpuscle),are located exclusively in the renal cortex.
The renal medulla contains the loops of Henle and the collecting ducts,while the renal capsule is the outermost fibrous covering of the kidney.

(D) In amniotes $(reptiles, birds, and mammals)$, the kidneys are $mesonephros$ during embryonic development but develop into $metanephros$ in the adult stage.
$Metanephros$ is the most advanced type of kidney, characterized by the presence of a ureter and a complex filtration system, which is an adaptation to terrestrial life.

(A) In a mammalian kidney,nephrons are classified into two types based on their position in the cortex: cortical nephrons and juxtamedullary nephrons.
Cortical nephrons are more numerous,accounting for approximately $80\%$ of the total nephrons.
Juxtamedullary nephrons are fewer in number,accounting for approximately $20\%$ of the total nephrons.
Therefore,cortical nephrons are more in number compared to juxtamedullary nephrons.

(A) The nephron,also known as the uriniferous tubule,is the structural and functional unit of the kidney.
It consists of two main parts: the glomerulus and the renal tubule.
The renal tubule begins with a double-walled cup-like structure called Bowman's capsule,which encloses the glomerulus.
Therefore,Bowman's capsule is an integral part of the uriniferous tubule.

(A) The kidney is divided into two main regions: the outer $Cortex$ and the inner $Medulla$.
Bowman's capsules,along with the glomeruli and the convoluted tubules ($PCT$ and $DCT$),are located in the renal $Cortex$.
The $Medulla$ primarily contains the loops of Henle and the collecting ducts.
Therefore,all Bowman's capsules are found in the $Cortex$.

(A) The $Nephron$ is the structural and functional unit of the kidney, which extracts waste products from the blood.
Each kidney contains approximately one million nephrons.
It is composed of two main parts: the $Bowman's$ capsule and the renal tubule.
Therefore, the correct option is $A$.

(A) Based on the anatomical diagram of the human excretory system:
$A$ points to the Kidney.
$B$ points to the Abdominal aorta (or dorsal aorta).
$C$ points to the Ureters.
$D$ points to the Urinary bladder.
$E$ points to the Urethra.
$F$ points to the Renal pelvis.
Therefore,the correct matching is $A$ = Kidney,$B$ = Abdominal aorta,$C$ = Ureters,$D$ = Urinary bladder,$E$ = Urethra,$F$ = Renal pelvis.

(C) The $pH$ range of human urine typically varies between $5.0$ and $7.5$.
Normal human urine is slightly acidic,with an average $pH$ value of approximately $6.0$.

(B) The correct option is $B$.
An average healthy adult human excretes approximately $1.5$ litres of urine in a $24$-hour period.
This volume can vary depending on the intake of water, environmental conditions, and the physiological state of the individual.

(A) The process of urine formation begins with the filtration of blood in the glomerulus.
Blood enters the glomerulus through a fine branch of the renal artery known as the $Afferent$ $arteriole$.
This vessel carries blood containing nitrogenous waste into the Bowman's capsule.
After filtration,the blood leaves the glomerulus through the $Efferent$ $arteriole$.
Therefore,the correct vessel leading blood into the Bowman's capsule is the $Afferent$ $arteriole$.

(C) The kidneys receive approximately $1100-1200 \text{ ml}$ of blood per minute,which constitutes about $1/5$th to $1/4$th of the blood pumped out by each ventricle of the heart in a minute.
To calculate the flow per hour: $1200 \text{ ml/minute} \times 60 \text{ minutes} = 72,000 \text{ ml/hour}$.
$72,000 \text{ ml/hour} = 72 \text{ litres/hour}$.
Among the given options,$50$ litres/hour is the closest approximation to the physiological range of renal blood flow.

(C) The correct answer is $C$. The afferent arteriole brings blood into the glomerulus,while the efferent arteriole carries blood away from it. To maintain high hydrostatic pressure in the glomerulus for ultrafiltration,the diameter of the afferent arteriole is significantly larger than that of the efferent arteriole. Therefore,the efferent arteriole is narrower than the afferent arteriole.

(B) The $Renal$ $vein$ carries blood away from the kidneys after the process of filtration and urine formation has occurred.
Since the kidneys filter metabolic wastes,including urea,from the blood,the blood exiting the kidneys through the $Renal$ $vein$ has the lowest concentration of urea compared to any other major blood vessel in the body.
Therefore,the correct option is $B$.

(D) nephron (or uriniferous tubule) consists of the glomerulus and the renal tubule. The renal tubule includes the Bowman's capsule,proximal convoluted tubule $(PCT)$,loop of Henle,and distal convoluted tubule $(DCT)$. The collecting duct is a separate structure that receives the filtrate from the $DCT$ of several nephrons. Therefore,the collecting duct is not a part of a single uriniferous tubule.

(A) If one kidney is removed,the remaining kidney undergoes a process called $compensatory\, hypertrophy$. In this process,the functional kidney increases in size and capacity to handle the entire workload of filtration and excretion,allowing the person to survive and lead a normal life.

(A) The renal pyramids are cone-shaped tissues located in the medulla of the kidney.
They primarily contain the loops of Henle and the collecting tubules (collecting ducts) of the nephrons.
The collecting ducts within the pyramids converge at the renal papillae to drain urine into the minor calyces,which then lead to the ureter.
Therefore,their primary function is to house the collecting tubules that transport urine toward the renal pelvis.

(B) The glomerulus is a tuft of capillaries formed by the afferent arteriole,which is a fine branch of the renal artery.
Blood enters the glomerulus through the afferent arteriole and leaves through the efferent arteriole.
The glomerulus,along with Bowman's capsule,forms the renal corpuscle (also known as the Malpighian corpuscle).

(A) In $Rana$ $tigrina$ (frog),the excretory system,including the kidneys and the ureters,is derived from the mesodermal germ layer during embryonic development.
Specifically,the kidneys develop from the intermediate mesoderm,and the ureters (or Wolffian ducts) also originate from the mesodermal tissue.
Therefore,both the kidney and the ureter are entirely mesodermal in origin.

(D) Nephrons are the structural and functional units of the kidneys. Each kidney contains approximately $1$ million nephrons. They are responsible for the filtration of blood and the formation of urine.

(A) $1$. Podocytes are specialized cells in the inner wall of Bowman's capsule that arrange themselves in an intricate manner to leave some minute spaces called filtration slits or slit pores,which are essential for the ultrafiltration of blood.
$2$. The Loop of Henle is primarily responsible for the concentration of urine,not the reabsorption of the majority of substances (which occurs in the Proximal Convoluted Tubule).
$3$. The Distal Convoluted Tubule $(DCT)$ is involved in the conditional reabsorption of $Na^+$ and water and selective secretion of hydrogen and potassium ions.
$4$. The Afferent arteriole brings blood into the glomerulus,while the Efferent arteriole carries blood away from it.

(C) In humans,the two kidneys are located on either side of the vertebral column in the abdominal cavity.
Due to the presence of the liver on the right side of the abdominal cavity,the right kidney is pushed slightly downwards.
Consequently,the left kidney is positioned at a slightly higher level than the right kidney.

(B) The $Renal \text{ } vein$ carries blood away from the kidneys after the process of filtration and reabsorption has occurred.
Since the kidneys are responsible for filtering metabolic wastes like urea from the blood, the blood exiting the kidneys via the $Renal \text{ } vein$ has the lowest concentration of urea compared to other major blood vessels.
The $Renal \text{ } artery$ brings blood to the kidneys with a high concentration of urea, while the $Hepatic \text{ } vein$ and $Hepatic \text{ } portal \text{ } vein$ are involved in the transport of blood related to the liver, where urea is produced.

(D) The human body possesses two kidneys,which are sufficient to filter the blood and maintain homeostasis. If one kidney is removed (nephrectomy),the remaining kidney undergoes a process called compensatory hypertrophy. This means the remaining kidney increases in size and functional capacity to handle the entire workload of filtration,ensuring that the individual survives without significant health issues.

(A) The renal artery enters the kidney and branches into smaller arterioles. The vessel that enters the Bowman's capsule to form the glomerulus is known as the $Afferent \text{ } arteriole$. The vessel that carries blood away from the glomerulus is the $Efferent \text{ } arteriole$. Therefore, the correct answer is the $Afferent \text{ } arteriole$.

(A) The afferent arteriole brings blood into the glomerulus,and the efferent arteriole carries blood away from the glomerulus. Both of these vessels are branches of the renal artery and are therefore arterial in nature. They are not veins.

(D) The nephron is the structural and functional unit of the kidney. It consists of two main parts: the renal corpuscle (glomerulus and Bowman's capsule) and the renal tubule (proximal convoluted tubule,loop of Henle,and distal convoluted tubule).
The collecting duct is not considered a part of the nephron because it receives filtrate from several nephrons and is not derived from the same embryonic structure as the nephron itself. Therefore,the correct answer is $D$.

(B) The Malpighian corpuscle,also known as the renal corpuscle,consists of the glomerulus and Bowman's capsule.
In the human kidney,these structures are located exclusively in the renal cortex.
The renal medulla contains the loops of Henle and collecting ducts,while the renal pelvis is the funnel-shaped space that collects urine.
Therefore,the correct option is $B$.

(B) Bowman's capsule is a cup-shaped structure that forms the beginning of the nephron in the kidney.
It consists of two layers: an outer parietal layer and an inner visceral layer.
The parietal layer of Bowman's capsule is composed of simple squamous epithelium,which is a single layer of flat,scale-like cells.
This thin layer allows for the efficient filtration of blood plasma into the capsular space.

(A) The kidney is the primary excretory organ in humans.
Each kidney contains approximately $1$ million complex tubular structures called nephrons.
Nephrons are considered the structural and functional units of the kidney because they are responsible for the filtration of blood and the formation of urine.
Therefore,the correct answer is Nephron.

(A) The process of urine formation involves filtration, reabsorption, and secretion.
$1$. In the Proximal Convoluted Tubule $(PCT)$, significant reabsorption of $Na^+$ and $K^+$ occurs.
$2$. In the Loop of Henle, reabsorption of $Na^+$ and $K^+$ occurs, particularly in the ascending limb.
$3$. In the Distal Convoluted Tubule $(DCT)$, conditional reabsorption of $Na^+$ and $K^+$ takes place under the influence of hormones like aldosterone.
$4$. The Bowman's capsule is the site of ultrafiltration of blood, where water and small solutes are filtered into the lumen, but no active or passive reabsorption of ions occurs here.

(B) The kidney has a notch on its inner concave surface called the $Hilum$.
Through this $Hilum$,the ureter,blood vessels,and nerves enter the kidney.
Therefore,the correct option is $B$.

(C) The kidney has a concave medial border.
Near the center of this concave border is a notch called the $Hilum$.
Through the $Hilum$,the ureter,blood vessels,and nerves enter the kidney.
Therefore,the correct option is $C$.

(D) The Loop of Henle is a critical component of the nephron responsible for the concentration of urine.
It is primarily found in mammals and birds,which are capable of producing hypertonic (concentrated) urine to conserve water.
Among the given options,mammals possess a highly developed and long Loop of Henle,which allows for the efficient reabsorption of water,a key adaptation for terrestrial life.
Therefore,the correct answer is $D$ (Mammals).

(D) Podocytes are specialized epithelial cells found in the visceral layer of the Bowman's capsule in the kidney.
These cells are arranged in an intricate manner so as to leave some minute spaces called filtration slits or slit pores.
Blood is filtered so finely through these membranes that almost all the constituents of the plasma except the proteins pass onto the lumen of the Bowman's capsule.
Therefore,the correct option is $D$.

(B) The $Renal \text{ } vein$ carries blood away from the kidneys after the process of filtration and urine formation has occurred.
Since the kidneys filter urea and other nitrogenous wastes out of the blood to form urine, the blood exiting the kidneys through the $Renal \text{ } vein$ has the lowest concentration of urea compared to any other major blood vessel in the body.
Therefore, the correct option is $B$.