Transcript Slide 1
November 5, 2014
Objective:
To describe the structure and function of the hair and nails
To make a model of the skin
Journal: What are two accessory organs that can be
found in the dermis?
Hair
Hair Functions
- Helps regulate body temperature
- Helps detect things on your skin
- Eyelashes and nose hairs are for protection
Hair Anatomy
Made up of dead keratinized
epithelial cells
Hair Shaft: the part that
protrudes above the skin
Hair Follicle: Tube-like hole in
the skin from which the hair
develops
Hair Anatomy Continued…
Hair Bulb: Expanded base
of the root
Hair Papilla: when the
dermis of the skin
projects into the base of
the hair to supply it with
nutrients from blood
vessels
Hair Anatomy Continued…
Arrector pili muscle:
contract to allow
hairs to stand up
straight
Two Stages of Hair Growth
Growth Stage:
Stem cells reproduce and differentiate to form epithelial cells,
which are then keratinized and die
The hair grows longer as cells are added to the base
Resting Stage:
No hair growth
Hair is held within the hair follicle
Duration of each cycle depends on the hair.
Hair Lifespan
Eyelashes lasts around 3 to 4 months
Hair on your head lasts about 3 to 4 years
It is normal to lose about 100 hairs a day.
Baldness occurs when the hair follicles are lost due to
genetic factors or testosterone
** Ingested substances can become part of a hair’s
composition, so the longer the length of the hair the
longer the record of what was consumed by the
individual.
Hair Color and Style
Dependent on the amount and type of melanin you
produce in the hair bulb
The more melanin, the darker the hair
White hair occurs in the absence of melanin
Red hair occurs when the melanin is altered and has
iron it in
Flat hair shafts = curly hair
Round hair shafts = straight hair
Nails
Nails
Nail Structure
Nails are thin plates made up of layers of keratinized
stratum corneum cells.
Nail body: visible part of the nail
Nail root: part of the nail covered by skin
Nail fold: the fold of skin that holds the nail in place
Nail Structure Continued…
Cuticle: stratum corneum cells from the nail fold that
extends on to the nail body
Nail Bed and Matrix: Stratum basale that produce
the cells that make up the nail body
Lunula: crescent shaped part of the nail matrix
Nail Growth
Nails grow continuously
Production of cells within the nail matrix results in
growth of the nail
What your nails can tell your about your health
Nail Shape and Texture:
Horizontal ridges - stress
Vertical ridges - arthritis
Vertical grooves - kidney disorders, aging, and iron deficiency
Markings:
Blue nail beds – not enough oxygen in the blood
Small white patches – zinc or calcium deficiency or parasites
Receded lunulae - poor circulation, shallow breathing habits,
or thyroid problems
Large lunulae (more than 25% of the thumb nail) - high blood
pressure.