in the kidney what is the correct sequence of formation of urine involves the following processes?
a). glomerular filtration, reabsorption, tubular secretion
b). reabsorption. filtration, secretion
c). filtration, secretion, reabsorption
d). reabsorption, secretion, filtration
The correct sequence of formation of urine in the kidney involves the following processes:
a). glomerular filtration, reabsorption, tubular secretion
To understand why this is the correct sequence, let's break down each step:
1. Glomerular filtration: This is the first step in urine formation where blood from the renal artery enters the glomerulus (the network of tiny blood vessels in the kidney). The pressure forces water, minerals, and waste products to be filtered out of the blood and into the glomerular capsule, forming a fluid called the filtrate.
2. Reabsorption: Once the filtrate is formed, reabsorption occurs. Some substances, such as glucose, amino acids, and water, are selectively reabsorbed back into the bloodstream from the renal tubules. This process helps maintain the body's water and electrolyte balance by returning necessary substances to the blood.
3. Tubular secretion: After reabsorption, certain substances that were not filtered initially, or actively secreted substances like hydrogen ions and drugs, are moved from the blood vessels surrounding the tubules into the filtrate within the tubules. This step allows the kidney to further eliminate waste products and control pH balance.
Therefore, the correct sequence is a). glomerular filtration, reabsorption, tubular secretion.