Hair Structure

Hair consists of two main parts: the hair shaft (visible part) and the hair follicle (beneath the scalp). Each component plays a vital role in hair growth, strength, and overall health.

头发结构

头发主要分为两部分：发干（露出头皮的部分）和毛囊（位于头皮下的部分）。

The hair shaft is the visible part of the hair made of keratinized protein and consists of three layers:

• Cuticle – The outermost protective layer composed of overlapping, scale-like cells. A healthy cuticle appears smooth and shiny, while a damaged cuticle leads to dull, brittle hair. The cuticle protects the inner hair structure from environmental damage and moisture loss.


• Cortex – The middle and thickest layer, primarily made of keratin fibers and pigment (melanin), determining hair strength, elasticity, and color. The structure of the cortex affects hair texture, from straight to curly. Damage to this layer weakens hair and leads to breakage.


• Medulla – The innermost core, present only in thick, coarse hair. It has an unclear function but may play a role in insulating hair strands. Fine hair often lacks a medulla.

发干（头皮以上的部分）
发干是我们肉眼可见的头发，由角蛋白组成，共有三层结构：

• 毛鳞片层（表层）：像鱼鳞一样一层层排列，是头发的保护层。健康的毛鳞片平整、有光泽；受损的毛鳞片粗糙，头发容易干枯、断裂。


• 皮质层（中层）：占头发的大部分，决定头发的强韧度、弹性和颜色。卷发或直发的形状也由这一层决定。若受损，头发容易断裂。


• 髓质层（内层）：位于最中心，仅存在于较粗的头发中，功能尚不明确，可能与保温有关。

The hair follicle is a dynamic, tunnel-like structure embedded in the scalp. It regulates hair growth and is connected to essential structures for nourishment and function:

• Hair Root – The growing part of the hair located inside the follicle, responsible for absorbing nutrients and developing new hair strands.


• Hair Bulb – The enlarged base of the follicle, where actively dividing cells (matrix cells) produce new hair. This is where keratinization occurs, transforming soft hair cells into hardened hair fibers.


• Dermal Papilla – A small, finger-like projection at the follicle base, rich in blood vessels and connective tissue. It supplies oxygen and essential nutrients to the hair bulb, directly influencing hair growth and cycle regulation.


• Sebaceous Glands – Oil-producing glands attached to the hair follicle. They secrete sebum, a natural oil that lubricates the hair and scalp, preventing dryness and breakage. Overproduction of sebum can cause an oily scalp, while underproduction leads to dryness.


• Arrector Pili Muscle – A tiny muscle attached to the hair follicle, responsible for the "goosebump" effect when contracted due to cold or emotional responses. This reflex also helps with heat retention.

毛囊（头皮以下的部分）

 毛囊就像是“头发的种子仓库”，深埋在头皮中，决定着头发是否能健康生长：

• 发根：藏在毛囊中的部分，负责吸收营养，促进头发生长。


• 毛球：毛囊底部的圆形区域，是新头发细胞不断生成的地方，头发的“制造工厂”。


• 真皮乳头：位于毛球底部，富含血管，为毛球提供养分和氧气，控制头发生长周期。


• 皮脂腺：毛囊旁边的小腺体，会分泌皮脂，滋润头皮和头发，防止干燥或断裂。油脂分泌过多会导致头皮出油，过少则会干痒。


• 立毛肌：连接在毛囊旁的小肌肉，当人受冷或情绪波动时，会收缩造成“鸡皮疙瘩”，帮助保温。

Scalp Structure

The scalp is a specialized skin structure that supports hair follicles, sebaceous glands, and sweat glands. It consists of three main layers:

• Epidermis (Outer Layer) – The protective barrier of the scalp. It contains basal cells that continuously regenerate new skin cells, replacing old ones. A healthy epidermis prevents scalp irritation, flaking, and excessive sensitivity.


• Dermis (Middle Layer) – The thickest layer of the scalp, housing hair follicles, sebaceous glands, sweat glands, nerve endings, and blood vessels. This layer is crucial for providing nutrients to the follicles and maintaining scalp health. Collagen and elastin in the dermis contribute to scalp elasticity and firmness.


• Subcutaneous Tissue (Deepest Layer) – A layer of connective tissue and fat that cushions the scalp, insulates against temperature changes, and supplies additional blood flow to hair follicles. This layer also helps anchor the hair follicles in place.

头皮结构

头皮是专门“为头发生长而设计”的皮肤结构，共分为三层：

• 表皮层（最外层）：是头皮的保护层，能不断生成新细胞，代谢老旧角质。健康的表皮层可以防止头皮干痒、屑多或敏感。


• 真皮层（中间层）：厚度最大，包含毛囊、皮脂腺、汗腺、神经末梢和血管，是供应养分和调节头皮状态的关键区域。


• 皮下组织（最深层）：由结缔组织和脂肪组成，起到缓冲保护、保温以及为毛囊提供血液支持的作用，也有助于固定毛囊结构。

A healthy scalp is the foundation for strong and resilient hair. By maintaining optimal follicle function, balanced sebum production, and proper scalp circulation, the hair growth cycle remains in its best condition.

小结：

健康的头皮是强韧秀发的基础。只有头皮环境良好，毛囊活跃，油脂分泌平衡，头发生长才能顺畅、持续。日常护理时，除了关注头发本身，也要重视头皮的清洁、滋养与健康。