The traffic are the substances which enter the human body ( anatomyland) through the gates and doors. The most important substances which enter the body which are considered or studied under traffic physiology are the passage of food and its routes , passage of water and its routes , passage of air and its routes. These are the external traffic. Internal traffic is the substances which are present inside the closed circulatory loops which circulates in only the loops but is not directly related to the outside going traffic but indirectly related.

• External traffic is again of two types
  • incoming traffic
  • outgoing traffic
• Internal Traffic
  • towards the cell
  • away from the cell

• traffic on the basis of substances they carry
  • air traffic which is studied under respiratory physiology under the process of respiration or breathing
  • water traffic which is studied under the digestive and excretory physiology along with cardiovascular systems.
  • food traffic is mainly studied under the digestive and cardiovascular systems
  • sperm and ova traffic which is studied under the reproductive systems