The Science of Hair

Hair Structure: From Root to Tip

Hair is more than just strands; it's a intricate biological structure with distinct components, each playing a vital role in its overall health and appearance.

The Hair Follicle: The Root of It All

The hair follicle, situated within the dermis layer of the skin, is a dynamic mini-organ responsible for producing hair. It comprises several key parts:

• Dermal Papilla: A cone-shaped structure at the base of the follicle, rich in blood vessels that supply nutrients essential for hair growth.
• Hair Matrix: Cells surrounding the dermal papilla that rapidly divide and differentiate to form the hair shaft.
• Inner and Outer Root Sheaths: These protective layers guide the growing hair shaft.
• Sebaceous Gland: Attached to the follicle, it produces sebum, a natural oil that lubricates the hair and scalp, providing a protective barrier.

The Hair Shaft: What We See and Feel

The hair shaft is the visible portion of the hair, composed primarily of a tough, fibrous protein called keratin. It has three main layers:

• Cuticle: The outermost layer, consisting of overlapping, flattened cells resembling scales. A healthy cuticle lies flat, reflecting light and giving hair its shine. Damage to the cuticle, such as from chemical treatments or excessive heat, can cause the scales to lift, leading to dull, rough, and tangled hair.
• Cortex: The middle and thickest layer, making up about 70-90% of the hair's weight. It contains keratin bundles, which give hair its strength and elasticity, and melanin, the pigment responsible for hair color.
• Medulla: The innermost core, present in some but not all hair types. Its exact function is not fully understood, but it may play a role in hair insulation.

The Hair Growth Cycle: A Continuous Process

Hair growth is not continuous but occurs in a cyclical pattern, with each hair follicle operating independently. There are three primary phases:

Anagen (Growth Phase)

This is the active growth phase, during which hair cells in the matrix rapidly divide, pushing the hair shaft upwards. This phase can last from two to seven years, determining the maximum length a hair can achieve. The duration of the anagen phase is genetically predetermined and varies between individuals and different areas of the body.

Catagen (Transition Phase)

Following the anagen phase, the catagen phase is a brief transitional period lasting about two to three weeks. During this time, hair growth ceases, the follicle shrinks, and the dermal papilla detaches from the hair matrix. This signals the end of active hair production for that follicle.

Telogen (Resting Phase)

The telogen phase is a resting period that typically lasts around three months. The hair remains in the follicle but is no longer growing. At the end of this phase, the old hair is shed, and a new anagen hair begins to emerge from the same follicle, pushing out the old one. It is normal to shed 50-100 telogen hairs per day.

Factors Influencing Hair Health and Growth

Several factors can significantly impact hair health and its growth cycle.

Nutrition

A balanced diet rich in essential vitamins, minerals, and proteins is crucial for healthy hair growth. Key nutrients include:

• Proteins: The building blocks of hair (keratin).
• Iron: Essential for red blood cell production, which carries oxygen to hair follicles.
• Biotin (Vitamin B7): Plays a role in keratin production.
• Vitamins A, C, D, and E: Support scalp health and hair growth.

Hormones

Hormonal fluctuations, such as those during pregnancy, menopause, or due to thyroid imbalances, can significantly affect hair growth and shedding. Androgens, a group of hormones, are particularly influential, with dihydrotestosterone (DHT) being a common contributor to hair thinning in genetically predisposed individuals.

Genetics

Genetics play a significant role in determining hair type (e.g., straight, wavy, curly), color, thickness, and susceptibility to conditions like androgenetic alopecia (pattern baldness).

Environmental Factors

External elements can also impact hair:

• UV Radiation: Excessive sun exposure can degrade hair proteins, leading to dryness and breakage.
• Pollution: Environmental pollutants can accumulate on the hair and scalp, contributing to damage and irritation.
• Mechanical Stress: Aggressive brushing, tight hairstyles, and excessive heat styling can cause physical damage to the hair shaft.

Hair Types and Characteristics

Hair characteristics vary widely among individuals, primarily influenced by the shape of the hair follicle.

Texture

Hair texture refers to the circumference of individual hair strands:

• Fine: Small circumference, prone to breakage.
• Medium: Average circumference, most common.
• Coarse: Large circumference, often more resilient.

Porosity

Hair porosity describes its ability to absorb and retain moisture, which is largely determined by the condition of the cuticle:

Porosity Type	Cuticle Condition	Characteristics
Low	Tightly closed	Resists moisture absorption, prone to product buildup.
Normal	Slightly raised	Balanced moisture absorption and retention.
High	Widely open	Absorbs moisture quickly but struggles to retain it, prone to dryness and breakage.

Elasticity

Hair elasticity is its ability to stretch and return to its original length without breaking. Healthy hair with good elasticity can stretch up to 50% when wet. It

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Find these ingredients in Watermans products

• Biotin — you will find this ingredient in our Hair Growth Shampoo.