Almost all the veins and arteries constrict and dilate during heavy exercise. Even capillaries bring a flush to the face and skin by dilation.
The release of inflammatory mediators such as histamine, prostaglandins, and nitric oxide causes arterioles in the damaged area to dilate. This dilation increases blood flow to the damaged tissues, bringing in immune cells and nutrients to aid in the healing process.
During exercise your muscles need more energy from respiration in order to contract. So your heart beats faster and the arteries supplying the muscles dilate (widen)
During exercise, diastolic pressure decreases because the blood vessels dilate to allow more blood flow to the muscles, which reduces the resistance to blood flow and lowers the pressure in the arteries.
Your Cervix
The drops the ophthalmologist put in my eyes made my pupils dilate.
Arterioles dilate in warm environments (vasodilation). Dilate means to open. Vasodilation is a process in which the increased blood flow through the dermis brings excess heat close to the body surface to be radiated to the environment. Arterioles constrict in cold environments (vasoconstriction). Constrict means to close. Vasoconstriciton is a process in which the decreased blood flow through the dermis keeps heat within the core of the body. Both take place to maintain homeostasis. In stressful situations, vasoconstriction takes place. It will shunt in the dermis or redirect blood to more vital organs such as the muscles, heart and brain.
Histamine
During exercise, the increased muscle activity increases body temperature. The skin responds to the need to bring body temperature back into normal range in two ways. The blood vessels near the surface of the skin dilate to release extra heat, and the sweat glands make perspiration, which evaporates to lower body temperature.
The SyNS pumps out epinephrine (adrenaline) during exercise to speed up heartrate, and regulate blood pressure. It also triggers the release of energy from your body's stores to fuel your muscles.
It keeps the blood vessels resilient and supple so that when an abrupt change in blood pressure occurs, for whatever reason the blood vessels can dilate or constrict to accommodate the change in blood pressure. In effect, exercise creates a pressure buffer to keep the blood pressure where it needs to be, thereby avoiding the possibility of damaging vital organs but especially the heart. Exercise creates a pressure buffer by conditioning the tone of the smooth muscle which covers the vessel and which is the means by which the vessel increases and decreases in diameter.
Blood flow to the kidneys and abdomen decreases duringexercise because the muscles need more oxygen, and so, the blood vessels in them dilate. This causes more blood to go to the muscles, leaving less blood in the rest of the body.