Final answer:
Renal tubular reabsorption is the process where the nephrons reclaim water and solutes that have been filtered out in the glomerulus, involving active or passive transport. Active transport is energy-dependent, whereas passive transport involves the movement of substances without energy input, often following concentration gradients.
Step-by-step explanation:
Renal tubular reabsorption is a critical part of kidney function where the nephrons reclaim water and solutes that have been filtered out in the glomerulus. Tubular reabsorption can involve either active or passive transport processes. Active transport usually occurs with substances that require energy for their movement against a concentration gradient, such as sodium (Na+), which is predominately reabsorbed in the proximal convoluted tubule (PCT) and regulated further along the nephron. On the other hand, water can be passively reabsorbed in the PCT due to the presence of aquaporins, which are specialized water channels, and it follows sodium to maintain osmotic balance.
Regarding the options given in the question, the correct statements about renal tubular reabsorption are:
- It could be both a limited "active" or freely "passive" transport process.
- Reabsorption of chloride is often associated with passive transport of water, as chloride movement can drive water reabsorption via osmotic forces.
It's important to note that tubular reabsorption happens in different parts of the nephron and not just the proximal and distal tubule. Additionally, reabsorption of water involves the uptake of water back into the bloodstream which concentrates the filtrate, not dilutes it. The movement of substances from the blood into the glomerulus is called glomerular filtration, not reabsorption.