PATHOLOGY

Detailed explanation-1: -Veins. These are blood vessels that take blood back to the heart; this blood lacks oxygen (oxygen-poor) and is rich in waste products that are to be excreted or removed from the body. Veins become larger and larger as they get closer to the heart.

Detailed explanation-2: -A decrease in oxygen pressure in arteries causes vasodilation of the cerebral arteries; however, an increase in oxygen pressure in arteries does not cause vasoconstriction.

Detailed explanation-3: -Tunica intima: The inner layer touches your blood and keeps it flowing smoothly through your arteries. Media: The middle layer is elastic, so it expands and contracts to maintain the right blood pressure in your arteries.