Basophils:
Basophils are a type of white blood cell that plays a role in the immune response. They contain granules filled with substances such as heparin and histamine, which are released into the blood in response to certain stimuli. These substances have important functions in the body's defense against pathogens and in the allergic response.

Heparin:
Heparin is an anticoagulant that prevents blood clotting. It is released by basophils and other cells called mast cells. Heparin works by inhibiting the activity of certain clotting factors in the blood, thereby preventing the formation of blood clots. This is important in preventing the blockage of blood vessels and maintaining the normal flow of blood throughout the body.

Histamine:
Histamine is a chemical messenger that is involved in many physiological processes in the body, including the immune response and inflammation. When released into the blood, histamine causes blood vessels to dilate, leading to increased blood flow to the site of infection or injury. It also increases the permeability of blood vessels, allowing immune cells and other substances to easily move out of the blood and into the surrounding tissue.

Mast cells:
Mast cells are similar to basophils in that they contain granules filled with heparin and histamine. They are found in connective tissue throughout the body, particularly in areas that are in contact with the external environment, such as the skin, lungs, and digestive tract. Mast cells are involved in both innate and adaptive immune responses and play a crucial role in allergic reactions.

Eosinophils and neutrophils:
Eosinophils and neutrophils are also types of white blood cells, but they do not release heparin and histamine into the blood. Eosinophils are involved in fighting parasitic infections and play a role in allergic reactions, while neutrophils are the most abundant type of white blood cell and are important in the initial stages of the immune response to infections.

In conclusion, the cells that release heparin and histamine into the blood are basophils and mast cells. These substances have important roles in the immune response and in the allergic response.