What contains blood vessels that nourish the growth zone of the hair?
-hair shaft
-arrector pili muscle
-hair root
-hair bulb in follicle
-cortex
-hair papilla
The correct answer is the hair papilla.
To arrive at this answer, let's break down the given options:
1. Hair shaft: The hair shaft is the visible part of the hair that extends above the surface of the skin. It is made up of dead cells, and therefore does not contain blood vessels.
2. Arrector pili muscle: This muscle is responsible for causing the hair to stand up (goosebumps) when it contracts. While it is associated with hair follicles, it does not contain blood vessels that nourish the growth zone of the hair.
3. Hair root: The hair root is the part of the hair located beneath the skin's surface. It is connected to the hair bulb and is responsible for anchoring the hair to the scalp. However, it does not contain the blood vessels that nourish the growth zone of the hair itself.
4. Hair bulb in follicle: The hair bulb in the follicle is where the hair is formed and where the growth of hair occurs. It is nourished by blood vessels present in the hair papilla.
5. Cortex: The cortex is the middle layer of the hair shaft, responsible for providing strength and elasticity to the hair, but it does not contain blood vessels.
6. Hair papilla: The hair papilla is a small, finger-like protrusion at the base of the hair follicle. It contains blood vessels, including capillaries, that bring nutrients and oxygen to the cells in the growth zone of the hair, supporting hair growth.
Overall, the hair papilla contains blood vessels that nourish the growth zone of the hair.