More blood is moved to internal organs
When it gets very cold blood is moved to the inner organs and squeezed out of the skin to keep the vital organs running smoothly and prevent their damage. This is why a person might feel very cold.
Shivering happens to produce heat
The muscles of the body start making random uncontrolled moves (shivering) to produce more heat to keep the inner body temperature fixed.
The body will slow down
As the body will try to spend its energy wisely the nervous system slows down, muscle movement will be reduced and lactic acid will be produced. All of those actions intend to keep preserve the body’s energy.
The metabolic rate might increase
As the body feels colder it needs to produce more energy from the food it has so the metabolic rate might speed up a little to burn more food and provide more energy to the body.
It might lose the ability to do simple tasks
Because blood is drawn away from non vital parts a person might lose some control over his fingers making it harder to type or open a door with a key. (See Why some people prefer winter over summer?)
Muscles become less flexible
As a result of the slowing down in muscle contractions to save energy the muscles become less flexible thus making it more likely for a person to get injured if he did a sudden unexpected move.
People feel like wanting to urinate
Because of the increased blood supply to the kidney some people feel like wanting to urinate when the weather gets really cold.
Mental confusion can happen at very cold temperatures
At very cold temperatures the body will try to reduce energy consumption as much as possible and this might result in a slow mind and some irrational decisions. Extreme cold can make a person mentally slow and can lead to wrong decisions.
The body shrinks
A person who feels very cold might involuntary bend himself to reduce the area exposed to the atmosphere. This can reduce down heat loss to the environment and help the body stay warmer.
Skin turns pale
Because blood is moved away from the skin to vital organs in cold weather the skin might turn pale or become blue. (See How to treat a Bad Cough?)
Blood pressure increases
Because the blood flawing to the skin is reduced the heart needs to do more effort to pump the blood in those narrow vessels. As a result blood pressure increases in cold temperatures.
If the skin temperature went very slow live skin cells might start freezing and dying as a result. After warming again the dead layer can be easily replaced by the body with another live layer if the damage was not severe.
What happens to the body in cold weather?
How does your Body deal with Freezing Weather? What happens to your body when it gets cold?