Kidneys are concerned with the functions of ......... and ………..

Explanation

**Step-by-Step Solution:**

1. **Identify the Functions of the Kidneys**: The kidneys are vital organs in the human body that perform several essential functions. The primary functions of the kidneys include the removal of waste products from the bloodstream and the regulation of various bodily fluids.

2. **Understand the Functional Unit**: The functional unit of the kidneys is called the nephron. Each kidney contains approximately one million nephrons, which are responsible for filtering blood and producing urine.

3. **Key Processes in Nephrons**: Within the nephron, three critical processes occur:
- **Filtration**: This is the first step where blood is filtered to remove waste products and excess substances.
...