8 Most VSAQ’s of Excretory Products and Their Elimination Chapter in Inter 2nd Year Zoology (TS/AP)

2 Marks

VSAQ-1 : Name the blood vessels that enter and exit the kidney.

The renal artery carries oxygenated blood into the kidney, and the renal vein carries deoxygenated blood away from the kidney.

VSAQ-2 : What are the columns of Bertin?

The columns of Bertin, also known as renal columns, are projections of renal cortex found in the kidney. These columns serve to divide and separate the renal pyramids and provide structural support to maintain the kidney’s shape.

VSAQ-3 : Define Glomerular filtration.

Glomerular filtration is the initial stage of urine formation that takes place in the kidneys. It occurs in the glomerulus and involves the filtration of blood to create a filtrate collected in Bowman’s capsule. This process relies on a pressure gradient and allows small molecules to pass into renal tubules, while larger substances like proteins and blood cells remain in the bloodstream.

VSAQ-4 : Define Glomerular filtration rate (GFR).

Glomerular filtration rate (GFR) is the measurement of the total amount of glomerular filtrate produced by all the nephrons in both kidneys per minute. In a healthy person, the average GFR is approximately 125 mL per minute. The glomerular filtrate contains various substances including glucose, amino acids, sodium, potassium, urea, uric acid, ketone bodies, and a substantial amount of water. GFR is a vital indicator of kidney function and overall kidney health.

VSAQ-5 : What is juxtaglomerular apparatus?

The juxtaglomerular apparatus (JGA) is a renal structure found in the kidneys at the junction of the distal convoluted tubule and the afferent arteriole near the glomerulus. It consists of two main cell types: the macula densa in the distal tubule and juxtaglomerular cells (or granular cells) in the afferent arteriole.

The JGA is crucial for regulating kidney function, primarily in blood pressure and glomerular filtration rate (GFR) control. It monitors changes in sodium concentration and blood pressure to regulate the release of renin, a hormone that influences blood pressure and fluid balance. The JGA is a vital component of the kidney’s homeostatic mechanisms.

VSAQ-6 : Distinguish between the enzymes renin and rennin.

Renin and rennin are two distinct enzymes with different functions

  1. Renin:
    • Produced in the kidneys.
    • Converts angiotensinogen (a plasma protein) into angiotensin.
    • Angiotensin I is further converted into angiotensin II in the lungs.
    • Angiotensin II is a potent vasoconstrictor and stimulates the secretion of aldosterone from the adrenal glands.
    • Aldosterone promotes the reabsorption of sodium and water in the kidneys.
    • Plays a crucial role in regulating blood pressure and fluid balance.
  2. Rennin:
    • Found in the digestive system, particularly in the stomach, mainly in infants.
    • Functions to curdle or coagulate milk protein (casein) into a semi-solid mass.
    • Aids in the digestion of milk.
    • Not present in the adult digestive system.
    • More relevant in the early stages of life when infants primarily consume milk.

VSAQ-7 : Name the structural and functional units of kidney. What are the two main types of structural units in it?

The nephron is the structural and functional unit of the kidney. It is responsible for the filtration, reabsorption, and secretion processes that regulate the composition of urine. Each kidney contains approximately 1,000,000 nephrons. Each nephron consists of two main parts:

  1. Renal Corpuscle: This is the initial filtering component of the nephron, consisting of two parts:
    • Glomerulus: A network of capillaries where blood is filtered.
    • Bowman’s Capsule: A double-walled capsule that surrounds the glomerulus and collects the filtered fluid.
  2. Renal Tubule: The filtered fluid from the renal corpuscle enters the renal tubule. It is a long, twisted tube that processes and carries away the filtered fluid, selectively reabsorbing substances needed by the body while eliminating waste products to form urine.

VSAQ-8 : Distinguish between cortical and juxta medullary nephrons.

  1. Cortical Nephrons:
    • Cortical nephrons make up about 80% of the total nephrons in the kidney.
    • They have a relatively short loop of Henle that extends only a short distance into the medulla.
    • Cortical nephrons are primarily located in the renal cortex.
    • Their main function is to filter blood and reabsorb essential substances.
  2. Juxtamedullary Nephrons:
    • Juxtamedullary nephrons account for approximately 20% of the total nephrons in the kidney.
    • They possess a long loop of Henle that extends deep into the medulla.
    • Juxtamedullary nephrons are situated at the border of the renal cortex and medulla.
    • Their primary role is to establish a concentration gradient in the kidney’s medulla, aiding in urine concentration and maintaining water balance.