Out of two principal subjects, the first one clearing the obstacles and cultivating the conducive motivation is complete with four subdivisions in itself. Now are going to deal with the second topic of actual process of death and what happens to the body and what are the outer and internal signs as the process death occurs.
Since the subjects and their sub-topics may just confuse the reader, I will explain it as plain as possible. When a person dies, the body gradually gives up its functions. When a car’s parts deteriorate and falls apart, that car becomes useless. Likewise, when our body decays through age or sickness, it deteriorates and becomes disfunctional  – this is called death. However, unlike any other philosophy, Buddhism and especially Tibetan Buddhism explains the stages of death and explain in great detail the processes which takes place unbeknownst to the living. First, here are the words of Panchen Lobsang Choegyan:

The body has weakened and the mouth and nose have raised. The body heat dissipates and the breathing becomes laboured and noisy, May I be able to generate strong Dharma motivation.

The above lines explains the process of death in a stage by stage development. Our body is said to constitute four elements – earth, water, fire and wind. The earth element constitute hard elements of the body such as bone, skin, nails and hair. The water constituents consists of the fluids of the body such as urine, bile and blood. The fire constituents consists of the heat that retains the body. The wind constituent is the currents of air that helps us to perform our daily habits of eating food by swallowing and defecating. The wind within our body helps to push them down or get rid of them.
The term dissolve means when one element’s capacity to support the body diminishes, it is called dissolve. When the capacity of the earth element diminishes the capacity of the water element becomes predominant. At such a stage, certain internal and external signs are experienced by the dying person. He or she may call out for help saying, “pull me up”. The dying person is experiencing ones body being heavy and sinking down to the ground. It senses the sinking sensation and asks to pull up.
Internally, it experiences an appearance of a mirage like image. The appearance people often experience on a hot day where the hot sun and the sand or the earth creates a shimmering image which looks like a running water. The dying person experiences this as an internal sign in the wake of the earth element dissolving into the water.

When the water element dissolves into the fire element, outer signs are: drying of mouth and nose. The teeth collects plaque (scum) and the lips become more wide and nose becomes sunken. The person cannot talk any more.
The internal signs are a smoke like image appearance to the dying person. It’s said to be like a blue puffs of smoke.
When the fire element dissolves into the wind, the outer signs are: the dying person loses body heat, whereupon the capacity to digest food and drink is lost. Those virtuous ones are said to dissipate the heat of the body from the lower part of the body first and then to the crown while the less virtuous ones are said to lose heat from the crown and down ward to the heel. This is also said to indicate whether the person is going to be born in happy realm or or less happy realm. Those whose heat dissipates from the lower part to the crown may be born in a happier rebirth than those who does the reverse.
The internal sign that appears is fireflies. It is like burning red sparks on the soot of a burning pan.

When the wind element dissolves into space/ consciousness, the dying person almost cease to breath. Clinically, he/she may be declared dead. All sensory organs now ceased to function and the wind element has begun the process of dissolving into the consciousness.  The internal sign is the appearance of a sputtering butter lamp. By this time the four elements have all dissolved and life has come to an end to the diseased as we know it conventionally.