anatomy of the hair
29/09/2007
Activity 1: hair structure
a) Describe, in detail, the structure of a hair identifying the 3 layers.
Hairs are dead structures that are made of hardened protein called keratin. Keratin provides the body with a protective toughness for its entire surface. Hair is comprised of 3 layers these are as follows the cuticle, the cortex and the medulla.
The cuticle is the outer layer of the scale cells with each scale overlapping each other towards the tip of the hair. This layer contains no pigment. The cuticle protects the hair.
The cortex is the main part of the hair it contains elongated cells, which are keratinised and cemented together. The pigment granules [melanin for black/brown or pheomelonin for red/yellow] are presented in this layer.
The medulla is the middle soft/spongy. Care of the hair. This layer contains large loosely be continues. The medulla is often not present in fine terminal and vellus hairs.
b) Compare the difference between a terminal hair and a vellus hair to include the structure and position.
Vellus hair
Terminal hair
Short/soft/downy hair
Coarse/long hairs
Often blonde or light coloured or lacks pigment
Normally dark and pigmented
Lacks a medulla
Has a medulla
Short active growing stage [anagen]
Long active growing stage [anagen]
Weak blood supply
Strong blood supply
Lie shallow in the follicle and near the skin surface
Lie deep in the follicle underneath the skin surface
Activity 2: hair growth
b) Describe the process of hair growth.
Anagen phase- anagen is the active phase of hair growth and generally last for several months. At any given time/most of our body hair is in this part of the hair growth cycle.
Canagen phase- during this brief phase the hair bulb regresses and begins to shrink.
Telogen phase- during this phase at the end of this resting phase which typically last a few months/hair is released and anagen phase begins again
c) List 3 factors,
Activity 1: hair structure
a) Describe, in detail, the structure of a hair identifying the 3 layers.
Hairs are dead structures that are made of hardened protein called keratin. Keratin provides the body with a protective toughness for its entire surface. Hair is comprised of 3 layers these are as follows the cuticle, the cortex and the medulla.
The cuticle is the outer layer of the scale cells with each scale overlapping each other towards the tip of the hair. This layer contains no pigment. The cuticle protects the hair.
The cortex is the main part of the hair it contains elongated cells, which are keratinised and cemented together. The pigment granules [melanin for black/brown or pheomelonin for red/yellow] are presented in this layer.
The medulla is the middle soft/spongy. Care of the hair. This layer contains large loosely be continues. The medulla is often not present in fine terminal and vellus hairs.
b) Compare the difference between a terminal hair and a vellus hair to include the structure and position.
Vellus hair
Terminal hair
Short/soft/downy hair
Coarse/long hairs
Often blonde or light coloured or lacks pigment
Normally dark and pigmented
Lacks a medulla
Has a medulla
Short active growing stage [anagen]
Long active growing stage [anagen]
Weak blood supply
Strong blood supply
Lie shallow in the follicle and near the skin surface
Lie deep in the follicle underneath the skin surface
Activity 2: hair growth
b) Describe the process of hair growth.
Anagen phase- anagen is the active phase of hair growth and generally last for several months. At any given time/most of our body hair is in this part of the hair growth cycle.
Canagen phase- during this brief phase the hair bulb regresses and begins to shrink.
Telogen phase- during this phase at the end of this resting phase which typically last a few months/hair is released and anagen phase begins again
c) List 3 factors,