Hair

Question 1

Hair bulb formation (3 steps)

Answer 1

1. The hair follicle forms from a cluster of cells in the basal layer (stratum germinitivum) of the epidermis. This cluster of cells is called the primitive hair germ
2. To get nourishment, the primitive hair germ works it’s way down in the dermal layer of the skin
3. As the primitive hair germ works it’s way down, the cell cluster pulls the upper layer down with it creating a pocket out of which the hair will grow

Question 2

The hair follicle (5 layers)

Answer 2

1. Inner root sheath (3 layers):
   - the cuticle- holds the hair in place
   - the Huxley layer=second layer of inner root sheath
   -the Henley’s layer= third and outermost layer of inner root sheath
2. Outer root sheath- surrounds the inner root sheath and does not grow with the hair
3. Connective sheath- surrounds the follicle and the sebaceous gland and provides the hair with the nerve endings and blood vessels
4. Hair bulb- the enlarged part of the hair at the base of the root
5. Dermal papilla- mass of loose connective tissue that contains capillaries to nourish all the cells of the follicle

Question 3

The germinal matrix, sebaceous gland and arrector puli muscle

Answer 3

GERMINAL MATRIX:
- area of cells around the dermal papilla and where cell division (mitosis) takes place
- the germinal matrix cells produce cells that keratinise (harden) 3 major layers of the hair
• cuticle= the outer layer covering the hair (transparent scales)
• cortex= consisting of unique protein structures that give hair most of its pigment and elasticity. It contains melanin that gives the hair its natural colour
• medulla= the central core of the hair

SEBACEOUS GLAND:
Attached to the side of the root sheath are bulges. These bulges are the beginnings of the sebaceous glands.

• sebaceous glands produce sebum and send it up through the hair follicles to prevent hair and skin from getting too dry
• sebum mixes with rhe body’s perspiration to form the acid mantle. The acid mantle protects the cuticle and maintains natural pH

AREECTOR PILI MUSCLE

Question 4

Amino acids= protein = hair (3 amino acids)

Answer 4

1. Protofibrils
2. Microfibrils
3. Macrofibrils