Flame cells are specialized cells found in flatworms that assist in osmoregulation and excretion. These cells are also known as protonephridia or solenocytes.

Flame cells play a crucial role in maintaining the internal environment of flatworms by regulating the osmotic balance and eliminating metabolic waste products. They are primarily involved in excretion and osmoregulation processes.

Explanation:

1. Structure of Flame Cells:
- Flame cells are found in the excretory system of flatworms, which is known as the protonephridia.
- Each flame cell consists of a bulb-like structure containing numerous cilia. These cilia are arranged in a tuft or flame-like appearance, giving the cell its name.
- The flame cells are interconnected through a network of tubules that extend throughout the body of the flatworm.

2. Function of Flame Cells:
- Osmoregulation: Flame cells help in maintaining the water and ion balance within the flatworm's body. The cilia present on the flame cells create a current that draws excess water and waste products from the interstitial fluid into the tubules.
- Filtration: As the fluid flows through the tubules, it passes through specialized cells called glandular cells. These cells reabsorb essential nutrients and ions while allowing the waste products and excess water to continue flowing towards the excretory pores.
- Excretion: The filtered fluid, now containing waste products, is eventually released from the body through excretory pores.

3. Mechanism of Excretion:
- The beating of cilia in the flame cells creates a negative pressure within the tubules, which draws fluid from the surrounding tissues into the tubules.
- As the fluid flows through the tubules, it undergoes filtration and reabsorption in the glandular cells.
- The filtered fluid, now called urine, is collected in a bladder-like structure known as the bladder or the collecting tubule.
- The urine is then expelled from the body through excretory pores located at specific regions of the flatworm's body.

In conclusion, flame cells are specialized cells found in flatworms that play a crucial role in osmoregulation and excretion. They help maintain the water and ion balance within the body by filtering waste products and excess water through a network of tubules. The cilia present on the flame cells create a current that drives the filtration and excretion processes, ensuring the flatworm's internal environment remains stable.