It content the basic information about the structure of hair and hair growth cycle . The information is helpful to know about the hair growth and it's process

1. HAIR
Basic Structure of Hair & Hair Growth Cycle
Komal S. Thakre , Kiran S Balbudhhe
Subject : Cosmetic Science B pharma Final Year
Subject Code: BP809ET
Guide name : Chandrashekhar M. Chakole

2. BASIC STRUCTURE OF HAIR
CONTENTS :
 External structure of hair
1. Infundibulum
2. Isthmus
3. Inferior Segment
 Internal structure of hair
1. Sebaceous gland
2. Arrector pili
3. Hair shaft
4. Hair bulb
 Hair growth cycle

3. INTRODUCTION
 Hair is consist mainly a protein called keratin.
 It has three main layers known are the cuticle, cortex,
and medulla.
 The structure of hair can vary between individuals
based on genetics and other factors.
 The follicle of hair is a sensing, reactive, and multi-
layered skin accessory.
 It can fulfils a number of essential purposes and
generally it need a specific molecular environment in
order to be left over fully functional.

4. EXTERNAL STRUCTURE OF HAIR
Infundibulum :-
 It is state from surface of opening of hair follicle and ends at the level of opening of
sebaceous gland.
It is part of the pilo-sebaceous canal and it used as rout e for the discharge of sebum
 Isthmus :-
 The isthmus is start from the infundibulum and ends at the level of insertion of arrector
pili-muscle.
 Inferior segment :-
Inferior segment is the part in the newly growing hair follicles are nearly same in diameter
except at the base level.

5. INTERNAL STRUCTURE OF HAIR
 Sebaceous gland
• These type of gland secrete sebum.
• It helps in the lubrication and protection of scalp and hair.
• These gland directly open at hair follicle.
Arrector pili
• These types of muscle are involuntary in nature and it is
controlled by autonomic nervous system .
• It is attached to the centre of hair follicle and works parallel to it.
• When there is sensation of cold and fear the arrector pili

6.  Hair Shaft :
 It is the part of the hair which present outside the skin surface
 The part present within the skin is known as hair root
 Hair Bulb:
 The bulb present at the end of hair root .
 IT has a innervated and vascularised central part which called as dermal papilla.
 This dermal papilla is liable for the growth of hair by absorbing nutrients.
 The hair bulb has a matrix which is produce by hair cells to mature and form hairs.

7. FUNCTIONS
Hair On The Head
• Protect the scalp from an UV light.
• It forms the cushion round the head .
Eyebrows
• It protect the eye tiny from foreign particles.
• It also divert sweat from the eyes.
Vibrissae
• They are the hairs guarding the entrance of nostril and ear
canals.
• It block the entry of small insects and filter the air .

8. HAIR GROWTH CYCLE
• Resting phase
• Lasts for 3
months
• Hair shedding
phase
• Hair detached
and falls out
• Transition
phase
• Lasts for only
2-3 weeks
• Hair growth
phase
• Last for 2-7
yrs.
Anagen Catagen
Telogen
Exogen

9. 1] ANAGEN PHASE :-
• Anagen is the 1st part of the hair growth cycle .
• It is also called as growing phase.
• In this phase the bulb cells multiply rapidly which results in upcoming hair
growth.
• These phase is lasts for 2 to 7 years and it can decide the Lenth of hair.
• Hairs present on eyebrows, eyelashes and body hair has a shorter phase in compare
to the scalp hair
• The factors like age, genetics, nutrition can affects the time period of anagen
phase.
2] CATAGEN PHASE :-
• This phase is runs after the anagen phase.
• It is a short time phase which is lasts only for 2 to 3 weeks.
• In the catagen phase the hair stop growing and detached from the blood vessels.
• The fully form hair stands are grew and after that it stop growing.

10. 3] TELOGEN PHASE :-
• The telogen phase is comes after the anagen phase .
• This phase is lasts for 3 months and the hair is replace by new hair.
• In this phase the club hairs are in rest phase.
4] EXOGEN PHASE:-
• It is the last phase of the hair growth cycle .
• During the exogen phase the fully grown hairs are detached from the
scalp and falls down .
• Normally 50-100 hair stands are lose each single day.
• After this phase the hair follicle get back to the anagen phase and the
cycle perform again.

11.  References
1. Singh P. S.,& Nigam V., First Edition., cosmetic science , thakur publication(2021).,37-40.
2. Mittal, B.M., & Saha R.N. (2000),a Handbook of cosmetic , Delhi: Delhi Vallabh Prakashan.
3. Deshmane S.V., Biyani K. R., Md Usman. A Textbook of cosmetic science , pee vee Publication.