Roger - Yes. All of your skin, except for your head and neck have blood vessels that constrict when you are cold and dilate when you are warm to regulate your body temperature. In order to not vary the blood supply to your brain, the head and neck blood vessels always stay the same size.
When you are backpacking, you will need to frequently adjust your thermal insulation up or down to stay in thermal balance. This occurs as you change your MET level, the terrain changes, or the effective environmental temperature changes. A zippered and hooded base layer / windshirt combination best allows quick broad spectrum thermal neutrality. Of course if the quick part is not a requirement, more conventional clothing like gloves, balaclavas and hats can be used in place of hooded base layers and windshirts. These separate options normally have less thermo neutral granularity, weigh more, and take more time to remove from or put back in your pack.