General Skin and Fascia

Functions

mechanical/permeability/UV barrier, immunologic information, homeostasis, sensory, endocrine and exocrine secretion

Layers of the integument

epidermis, dermis, hypodermis

Epidermal layers

Stratum corneum, stratum lucidium, stratum granulosum, stratum spinosum, stratum basale

Stratum corneum

dead and flattened cells, bags of bundled keratin

Stratum lucidium

waterproofing, loose organelles, contains lipids

Stratum granulosum

older keratinocytes, bundled keratin

Stratum spinosum

keratinocytes, provides most thickness of epidermis

Stratum basale

cuboidal stem cells

Pigmentation of the skin

melanocytes secrete melanosomes, which produce melanin

Layers of dermis

Papillary layer (thin collagen fibers), reticular layer (thick collagen fibers), + dermo-epidermal junction

Always cut….to tension lines

parallel

Stratum corneum description

protects against abrasion

stratum lucidium description

water barrier- sometimes missing

Stratum granulosum

bundles keratin filaments

Stratum spinosum

skin cells progressively getting older

Stratum basale

stem cells

How does epidermis get blood supply?

via dermal papilla, outpouching of dermis that provide oxygen and nutrients by diffusion

Free nerve endings

PAIN, temp, touch (epidermis)

Merkel’s cell

modified basal cell, sensitive touch (epidermis)

Pacinian corpuscle

Deep pressure, vibration, capsule (dermis)

Meissner’s corpuscle

sensitive touch, capsule (dermis)

Thick skin

glaborous

Thin skin

hairy

Soft cornification

mammal and bird skin, reptile interscale skin

Hard cornification

scales, claws, nails, feathers, hair

skin modification

glaborous skin, involves ALL layers (epidermis, dermis, hypodermis)

skin appendages

epidermis extending into dermis

ex of modifications

dog’s nose, paw pads, velvet on top of anters, lips

ex of appendages

Fair follicles, glands (sebaceous, eccrine, and apocrine)

Vibrissae

sinus hairs or sensory hairs, hair moving changes pressure in sinus, which activates nerves

Hypodermis is also…

sperficial fascia