Summary of hair structure

Hair structure and related factors

1. STRUCTURE OF HAIR AND HAIR GROWTH CYCLE

2. Contents: Introduction Hair structure Hair growth cycle Hair problems Treatment for hair care Strategies for healthy hair References

3. THE HAIR : Hair is a protein filament that grows from follicles found in the dermis, or skin. Hair is composed of protein called keratin. This is the same kind of protein that makes up the nails and the outer layer of skin. Hair act as a barrier to foreign particles. The hair follicle is a pocket of skin and grows deep into the dermis and consists of the following : Papilla Germinal matrix Hair bulb

4. The hair follicle: Fig.: 1 Hair Follicle

5. The papilla: Found below the follicle in the dermis. Is located at the base of the follicle. Is where the capillaries pass nutrients through to dividing cells in the germinal matrix. Where the waste products from the cell are passed back through to the capillaries and taken away.

6. 2) The germinal matrix: Inside the follicle above the PAPILLA. Were the cells divide (mitosis) Each cell already knows if it is a cortex , cuticle or medulla. Melanin is produced in the cells within the germinal matrix. Cells are being pushed upwards as new cells are produced. Once the cells leaves the germinal matrix its supply of nutrients is cut off so he cells stop dividing and dies.

7. 3) The hair bulb: Bulb shape located at the lower end of the follicle. The germinal matrix is found in the hair bulb. Keratinisation occurs here. Sebaceous gland: Attached to the side of the follicle. Secretes oil (sebum). Helps hair stay supple and shiny. Sebum forms part of the acid mantle that helps protect the skin from harmful bacteria and chemical attack.

8. Arrector pili muscle: Attached to the follicle and the base of the epidermis. Involuntary muscle- can not control it. Contracts due to cold creating goose bumps. The main function and role of the hair. Thermo regulation - helps retain body heat. Physical protection - act as a buffer to knocks and abrasions. Provides a good environment for micro organisms - increased warmth, moisture and sebum under hair. THE HAIR STRUCTURE:

9. Layers of the hair: The hair shaft consists of three layers: MEDULLA CORTEX CUTICLE Centre layer of hair shaft. Not always present. Can be continuous or broken. Made up of large loosely connected cells. May contain melanin. Largest and most important layer of the hair shaft. Determines the texture of the hair. All chemical and physical changes take place here. Melanin is found here- permanent colour changes takes place in the cortex. The outer layer . It is formed from dead cells, overlapping in layers, which form scales that strengthen and protect the hair shaft. Contains no melanin. Protects the cortex.

10. HAIR GROWTH CYCLE: Losing around 80-100 hairs a day is common. A new hair grows when the old one falls. It’s a cycle. Hair fall of more than 100 a day may cause baldness. The growth phase ( anagen phase) The transition phase ( catagen phase) The resting phase ( telogen phase) There are always, 85% of hairs in growth phase. 14% of the hairs in resting phase. If the ratio gets unbalanced than hair fall is assumed to happen. Hair cycle consists of three stages:

11. 1) The growth phase ( anagen ): It lasts around 2 to 6 years. Key phase for the formation of healthy hairs. Active metabolism of the hair root insures rapid division of hair cells. New hair is formed and grows. Hair is particularly sensitive. Stress or nutritional deficiencies may affect on the growth of the hair.

12. 2) The transition phase ( catagen ): It lasts just a few weeks. Growth stops. Hair cell division declines. Root shrinks to 1/3 rd of its actual size. Hair detaches it self from root and travels upward in the scalp. Hair formed is known as club hair.

13. 3) The resting phase ( telogen ): It’s the last phase with the lasting period of 2 to 3 months. Hair follicle is at complete rest. Club hair is completely formed. Pulling a hair out will reveals solid, hard , dry, white material at the root.

14. FACTORS AFFECTING NORMAL HAIR GROWTH CYCLE : Change in diet. Drug such as cytotoxic drug. Stress. Illness. Lifestyle. Alcohol and smoking. Hypertension. Severe illness.

15. HAIR PROBLEMS AND TREATMENT: 1) Dandruff: Dry skin Not shampooing often Fungus Allergy to hair care product Anti-dandruff treatment: Example ketoconazole shampoo Zinc pyrithione shampoo 2) Scalp psoriasis: Causes- it comes from something wrong with immune system that cause skin cells to growth too quickly and build up into patches. Treatment- shampoo containing coal tar, salicylic acid.

16. STRATEGIES FOR HEALTHY HAIR: Avoid direct sun exposure. Eating fresh fruits and meals. Enhanced uptake of biotin (B5). Avoid alcohol. Pyridoxine (B6) prevent dandruff. Methyl cobalamine (B12) prevent hair loss. Do not use hair colour/ dyes. Avoid excess heat to your head. Extremely hot water will leaves your hair dehydrated and brittle.

17. REFERENCES: P. P. Sharma, Cosmetics- Formulation, Manufacturing And Quality Control, 5 th edition, Published by Vandana Publications, Page No. 319-325. Y. Madhusudan Rao, Shayeda , Cosmeceuticals , Page No. 356-357. Harry’s Cosmeticology , Volume 1 of 2, 8 th edition, Published by Chemical publishing Co. Inc. New york . Haward I. Maibach’s Handbook Of Cosmetic Science and Technology, third e dition, Published by Informa Healthcare USA Inc. Newyork – 10017 www.google.Com

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