vasokonstrikció

Vasokonstrikció, also known as vasoconstriction, is the narrowing of blood vessels. This physiological process is crucial for regulating blood flow and blood pressure throughout the body. It occurs when the smooth muscles in the walls of arteries and veins contract, reducing the diameter of the lumen, the hollow space within the vessel.

Several factors can trigger vasokonstrikció. Hormones like adrenaline (epinephrine) and noradrenaline (norepinephrine), released during stress or physical exertion, are potent vasoconstrictors. These hormones bind to receptors on the smooth muscle cells, causing them to contract. Other factors include the sympathetic nervous system, which can directly stimulate vasoconstriction, and certain local chemicals, such as thromboxane A2, which is involved in blood clotting.

The effects of vasokonstrikció are significant. By reducing blood flow to certain areas, it can help conserve heat in cold environments or redirect blood away from non-essential organs during emergencies, prioritizing blood supply to vital organs like the heart and brain. Conversely, when vasokonstrikció is excessive or prolonged, it can lead to dangerously high blood pressure (hypertension) and reduce the oxygen supply to tissues, potentially causing damage. Conditions like Raynaud's phenomenon are characterized by exaggerated vasokonstrikció in the extremities. The opposite of vasokonstrikció is vasodilation, the widening of blood vessels.