skin accessories and receptors

Skin accessories

Hair, Nails

Structure of the hair

shaft, root, follicle, sebaceous gland, arrector pili muscle, bulb

Shaft

Visible part

Root

Below the skin

Follicle

Tubular structure surrounding the root

Arrector pili muscle

Contracts = Goosebumps

Bulb

Contains living matrix cells that divide to produce hair

Layers of the hair shaft

medulla, cortex, cuticle

Medulla

Center, contains soft keratin

Cortex

Thickest, stores melanin

Cuticle

Outermost, overlapping keratin plates

What determines the shape of hair?

Follicle shapes

Round follicle

Straight

Oval follicle

Wavy

Flat/Elliptical follicle

Curly

Structure of the nails

plate, root, lunula, matrix, cuticle, hyponychium

Plate

Visible, hard keratin

Matrix

Actively dividing cells

Hyponychium

Under free edge

Functions of the nails

Protect, Grip

Dark nails show

Low oxygen, anemia, circulation issues

Brittle

Malnutrition, iron deficiency

White spots

Minor trauma to nail matrix

Black

Bruising, fungal infection

Sensory receptors

Mechanoreceptors, Thermoreceptors, Nociceptors

Mechanoreceptors

Meissner’s corpuscles, Merkel cells, Pacinian corpuscles, Ruffini endings

Thermoreceptors

Krause end bulbs, Ruffini endings

Nociceptors

Free nerve endings

Free nerve endings Stimulus

Pain, Temperature, Light touch, Itch & tickle

Krause end bulbs Stimulus

cold receptors, detect low-frequency vibration or light touch

Ruffini endings
 Stimulus

Skin stretch, Sustained pressure, proprioception, Good for grip adjustments

Meissner’s corpuscles
 Stimulus

Light touch, Very low frequency vibration, Fine tactile

Merkel cells Stimulus

Fine, discriminative touch, Edges, shapes, and textures, Sustained pressure

Pacinian corpuscles
 Stimulus

Deep pressure, High frequency vibration

lunula

contains matrix where cell division happens

skin accessory hard to work without

nails because they’re used for grip and picking up

how do arrector pili muscle causes goosebumps

when they contract, pulling hair follicles upright and causing the surrounding skin and muscles to tighten