Guru Nanak Institute of Pharmacy and Technology
HAIR STRUCTURE AND HAIR GROWTH
CYCLE
NAME- KOUSHIK SHIL SHARMA
ROLL NO- 186122401006
SUBJECT CODE-R20_MPT2064T
SUBJECT- COSMETICS AND COSMECEUTICALS
SEMESTER- 2nd
Hair
Hair is a keratin-based filament growing from follicles in the skin.
It plays important roles in
• Protection(e.g. eyebrows and eyelashes shield from dust)
• Sensory perception(torch receptors)
• Temperature regulation(scalp hair insulates)
The human body has about 5 million hair follicles, with around 100,000 on the
scalp.
Structure of Hair
It basically divide into two parts
❑ Hair shaft- The visible, non-living part
above the skin.
❑ Hair Root- Located inside the follicle,
where growth occurs
Hair structure
Three layers of shaft
▪ Cuticle- Outermost layer,protects inner layer.
▪ Cortex- Middle layer, contain melanin and gives strength.
▪ Medulla- Innermost layer, absent in line hair.
Hair shaft
Hair Follicle structure
It is a tunnel-shaped structure in the skin that produces hair
The key components are-
• Hair Bulb- Base of the follicle, contain living cells.
▪ Dermas Capilla- Supplies nutrients via blood vessels.
▪ Sebaceous gland- Secretes oil to condition hair.
▪ Arrector pill muscle- Causes hair to stand(goosebump).
Hair follicle structure
Hair Color and melanin
Melanin, produced by melanocytes, determines hair colour.
There are two types of melanin-
▪ Eumelanin- Black and brown pigment
▪ Pheomelanin- Red or yellow pigment.
Gray or white hair occurs due to reduced melanin The combination of
production, often linked to- these pigments creates
• Aging- Melanocyte activity declines different hair colours.
• Genetics- Family history cause early graying
• Oxidative stress- Free radicals damage melanin-
producing cells.
Hair Texture and shape
Hair texture is influenced by the shape of the follicle
• Round follicle- straight hair
• Oval follicle- Wavy hair
• Flat follicle- Curly hair
External factors affecting texture affecting texture Keratin bonds and
• Heat styling, humidity and chemical treatments protein cross-linking
• Hormonal changes can alter hair texture over time. impact hair elasticity
Introduction of Hair Growth Cycle
Hair undergoes a continuous cycle of growth, rest The growth cycle is
and shedding. Growth cycle ensures constant hair influenced by genetics,
renewal. Each follicle operators independently, so all hormones and
hairs don’t shed at once. environmental factors
On average, a person loses 50-100 hairs per day.
Hair growth cycle
Phases of hair growth cycle
Anagen phase- Catagen(Transition Phase)- lasts
It is growth phase which lasts for 2-3 weeks.
2-7 years. Follicle shrinks, cutting off blood
85-90% is in this phase at any supply
time
Exogen(Shedding phase)- Telogen(Resting Phase)-
Hair falls out as new hair Lasts 3-4 months.
emerges. Hair stops growing but remains
attached.
Factors affecting hair growth
Internal Factors
• Genetics- Determines growth rate, colour, and thickness.
• Hormones- DHT causes hair thinning in androgenic alopecia
• Nutrition- Defeiciency in iron,biotin or protein weakens hair.
External factors
▪ Heat styling and chemicals damage the cuticle.
▪ Pollution and UV rays cause oxidative stress.
▪ Hairstyles and tension(light braids, ponytails) lead to traction alopecia.
Hair Care and follicle
health
Healthy hair starts with a healthy scalp.
Nutrition for hair growth are protein, biotin, omega-3s and vitamins
A,D and E.
Avoid excessive heat styling and chemical treatments.
Use mild, sulfate-free shampoos to prevent stripping natural oils.
Massage the scalp to boost blood circulation
Recent Advances in hair growth
research
Stem cell
PRP Therapy
therapy
Platelet-rich plasma stimulates Promising for hair follicle
follicle regeneration renewal
Minoxidil and Hair cloning and 3D
Finasteride bioprinting
FDA-approved treatments for Potential future treatments for
hair loss. baldness,
Conclusion
Hair is a complex structure composed of keratin, with both a visible shaft
and a follicle embedded in the skin. The hair growth cycle consists of anagen
(growth), catagen (transition), telogen (resting), and exogen (shedding)
phases, ensuring continuous renewal. Hair health is influenced by genetics,
hormones, nutrition, and external factors like styling and environmental
exposure. Proper care, including a balanced diet, scalp health, and avoiding
harsh treatments, promotes strong, healthy hair. Ongoing scientific
advancements in hair regrowth, such as PRP, stem cell therapy, and hair
cloning, offer promising solutions for hair loss management.
Reference
❖ Alonso, L. C., & Fuchs, E. (2006). The hair cycle. Journal of Cell Science, 119(3), 391–
393. https://doi.org/10.1242/jcs.02793.
❖ Greco, V., Chen, T., Rendl, M., Schober, M., Pasolli, H. A., Stokes, N., Dela Cruz-
Racelis, J., & Fuchs, E. (2009). A two-step mechanism for stem cell activation during hair
regeneration. Nature, 457(7230), 818–821. https://doi.org/10.1038/nature07572
❖ Lin, X., Zhu, L., & He, J. (2022). Morphogenesis, growth cycle and molecular regulation of
hair follicles. Frontiers in Cell and Developmental Biology, 10, 899095.
https://doi.org/10.3389/fcell.2022.899095
❖ Paus, R., & Foitzik, K. (2004). In search of the "hair cycle clock": a guided tour.
Differentiation, 72(9–10), 489–511. https://doi.org/10.1111/j.1432-0436.2004.07209004.x
❖ Schneider, M. R., Schmidt-Ullrich, R., & Paus, R. (2009). The hair follicle as a dynamic
miniorgan. Current Biology, 19(3), R132–R142. https://doi.org/10.1016/j.cub.2008.12.005
❖ Stenn, K. S., & Paus, R. (2001). Controls of hair follicle cycling. Physiological Reviews,
81(1), 449–494. https://doi.org/10.1152/physrev.2001.81.1.449
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