How Hair Grows - And How it is Lost!

Background behind how human hair grows and is therefore lost

Before we can begin to understand how our hair is lost, and therefore; how we can begin to treat and solve the problem, we must first understand how human hair grows in the first place.

Factors Contributing to Our Hair Types

The first step in understanding this process is the realization that not everyone has the same kind, type, texture and weight of hair. We are all born genetically pre-disposed to having certain kinds of hair. Theres no getting around that. Even within family units, it is quite common to see siblings, from the same set of parents, have two different kinds of hair. One may have thicker hair, while the other has thin, fine hair.

Secondly, there are many other factors that play into our hair type, and growth, besides genes. Some of these factors we have control over, and some we do not. Among just a few of these factors are weight, age, medical conditions and medications, metabolisms and hormones. Stress levels can also play a key role in how our hair grows, develops and is shed. Weve all heard the expression I feel like pulling out my hair. While very few people actually progress to this step, stress can have a very profound effect on our bodies, including our hair. Extreme amounts of stress can result in hair thinning, premature graying and the loss of hair.

Finally, our hair type does not remain constant throughout our lives. This is no big surprise to most people. It is a well known fact that as we increase in age, our hair volume decreases.

Critical to understanding hair loss, is becoming familiar with the types of hair grown on our body and how each type of hair grows. The hair grown on our scalp is not the same kind of hair that grows elsewhere on our body. That is one of the reasons why we see such an odd phenomenon as we increase in age-hair on our scalp begins to decrease as hair on other parts of our bodies begin to increase-some in places where we previously had little to no hair!

The Makeup of the Human Hair

The average person has at least 100,000 to 150,000 strands of hair on their head. Each one of these strands of human hair is made up of several components, each one of which plays a different role in the growth of hair. While we sometimes complain about our hair having dead ends, the truth is that for the most part hair is comprised of mainly dead skin cells along with tissue, keratin and proteins.

One single strand of hair is composed of numerous individual parts, all of which have a specific role in the overall hair growth process. Below are the common terms used to refer to the different parts of each individual hair strand structure and the purpose of each component as well as a explanation for the role these components play in the hair growth process.

Hair Follicle-The hair follicle is found on the skin, on most places of the body, and is formed by skin cells bunching together. The sebaceous glands, responsible for the production of oil on our skin and hair; is found inside the hair follicle. Hair follicles range in size; depending upon the kind of hair strand they are attached to as well as the phase of growth that particular strand of hair is undergoing. Kinds of hair and hair growth phases will be discussed in more detail later.

Hair Shaft- This is the portion of the hair that protrudes just above the skin and contains, among many things, older skin cells that have died as well as pigment and protein keratin. There are actually three parts to the hair shaft; the outer layer, middle layer and innermost layer.

Outer Layer Hair Shaft- Known as the cuticle, this portion of the hair shaft contains layers of cells that are connected to the inner root shaft.

Middle Layer Hair Shaft This portion of the hair shaft is known as the cortex. The cortex is responsible for the overall strength of the hair and also determines the color of the hair strand as well as the texture.

Inner Layer Hair Shaft Also called the medulla, this layer of the shaft contain extremely small cells and is generally only seen in thick strands of hair. Therefore, some hair strands may contain and inner layer hair shaft (medulla) and some may not.

Cortical cells-Contains cigar shaped microfibril cells composed of keratin proteins.

Hair Bulb-If youve ever plucked a hair, you will have noticed a tiny white pustule at the base of the hair; this is the hair bulb. The bulb, along with blood vessels, form the root of the hair, attaching it to the scalp.

Hair cuticle- The hair cuticle forms the outer covering of the hair strand and has protective qualities.

Outer Root Sheath-This component surrounds the hair follicle, covering the inner root sheath.

Connective Tissue-Connective tissue provides imperative physical support for the hair follicle. In younger individuals the connective tissues contain elastic properties. Studies have shown that the elasticity of connective tissues begins to erode with advancing age.

Erector pili Very small muscle, microscopically sized, found within the follicular unit.

Follicular unit Small grouping of anywhere between one to five hairs contained within the same anatomic unit.

Papilla- The papilla is found at the base of the hair follicle. This is the primary location where the cells that form hair are produced. Blood vessels are connected to the papilla, which send necessary proteins and vitamins to the roots to nourish the hair.

Sebaceous gland This gland is responsible for the secretion of a substance known as sebum, a very oily manner. Sebum is made up of a mixture of the remains of dead skin cells and fat. The individual hair strands receive sebum while still inside the hair follicle. As the strand of hair is pushed up out of the follicle, the sebum remains. The healthy function of the sebaceous gland is believed to critical in the production of healthy hair as well as preventing loss of hair. Some studies have indicated that the failure of the sebaceous gland to function properly may lead to certain types of hair loss.

Next: How Nutrition Affects Hair Growth

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How Hair Grows - And How it is Lost!