Histamine

Definition

Histamine is a biologically active amine involved in local immune responses. It plays a key role in inflammation and allergic reactions.

5 Must Know Facts For Your Next Test

1. Histamine is released by mast cells and basophils during an immune response.
2. It increases the permeability of blood vessels to allow immune cells to access infected tissues.
3. Histamine binds to its receptors, H1 through H4, each mediating different physiological effects.
4. Excessive histamine release can lead to hypersensitivity reactions such as hay fever or anaphylaxis.
5. Antihistamines are drugs that block histamine receptors to reduce symptoms of allergies.

Review Questions

Related terms

Mast Cells:

Immune cells that release histamine and other chemicals during inflammatory and allergic reactions.

Basophils:

A type of white blood cell that releases histamine and heparin as part of the body's immune response.

Anaphylaxis:

A severe, potentially life-threatening allergic reaction caused by excessive release of histamine.