2. Did something shy

When a person does or sees or hears something shy, his eyes and ears will immediately transmit the message to the cerebral cortex, which will stimulate the adrenal gland in addition to contacting the relevant parts. When the adrenal gland is stimulated, it will respond immediately and secrete adrenaline. Adrenaline has a characteristic. When it is secreted in a small amount, it can make the blood expand without reflux, especially the subcutaneous small blood vessels of the face. But when it is secreted in large quantities, it will cause vasoconstriction.

When we feel embarrassed, it is the cerebral cortex that stimulates the adrenal gland and secretes a small amount of adrenaline, so our faces are hot and red.