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.

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 monthsHair on your head lasts about 3 to 4 yearsIt 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 hairWhite hair occurs in the absence of melaninRed hair occurs when the melanin is altered

and has iron it inFlat hair shafts = curly hairRound 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 nailNail root: part of the nail covered by skinNail 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 continuouslyProduction 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.