Kärlsammandragning

Kärlsammandragning, also known as vasoconstriction, is the narrowing of blood vessels. This physiological process is primarily controlled by the smooth muscles in the walls of arteries and veins. When these muscles contract, the diameter of the vessel decreases, reducing blood flow through it.

Vasoconstriction plays a crucial role in regulating blood pressure and body temperature. For instance, in response to cold, blood vessels in the skin constrict to conserve heat, diverting blood flow to the core of the body. Conversely, during stress or exercise, the body may constrict certain blood vessels to redirect blood to vital organs and muscles. Hormones such as norepinephrine and angiotensin II are potent vasoconstrictors, while certain local factors and nerve signals can also trigger this response.

The opposite of vasoconstriction is vasodilation, the widening of blood vessels. Maintaining a balance between these two processes is essential for cardiovascular health. Pathological vasoconstriction can contribute to conditions like hypertension, Raynaud's phenomenon, and certain types of headaches. Medical interventions to manage these conditions often involve medications that promote vasodilation.