* Anaerobic respiration is the process by which cells obtain energy from glucose in the absence of oxygen.

* It is a less efficient process than aerobic respiration, and produces less ATP.

* The end products of anaerobic respiration are lactic acid and ethanol.

* Lactic acid build-up can cause muscle fatigue and soreness, and can eventually lead to cell death.

* Ethanol is a toxic substance that can damage cells and organs.

Here is a more detailed explanation of what happens when oxygen is not available to an animal cell:

1. The cell's mitochondria can no longer produce ATP, the cell's energy currency.

2. The cell's energy levels drop, and the cell begins to die.

3. The cell's pH level drops, causing the cell to become more acidic.

4. The cell's enzymes begin to denature, and the cell's structure begins to break down.

5. The cell eventually dies and releases its contents into the surrounding environment.

Anaerobic respiration is a temporary survival mechanism that allows cells to continue to function for a short period of time in the absence of oxygen. However, it is not a sustainable process, and cells will eventually die if oxygen is not restored.