Integumentary System and It's Functions

Epidermis

• Superficial layer of stratified squamous epithelial tissue

• Protection and prevents water loss

• Contains 5 deep to superficial layers

Stratum Basale

• deepest level of epidermis

• composed of a single layer of cuboid cells, Merkel cells, and melanocytes

• high mitotic activity

Stratum Spinosum

• 8 to 10 layers of keratinocytes

• named for spiny appearance

Stratum Granulosum

• 3 to 5 layers of keratinocytes

• Grainy layer due to keratinization

• Keratinocytes fill with keratin

• causes nucleus and organelles to disintegrate

Stratum Lucidum

• 2 to 3 cell layers

• found only in thick skin of palms and soles

Stratum Corneum

• 15 to 10 layers layer of dead, keratinized cells

• most superficial layers

• water resistant

Dermis

• deep layer of connective tissue

• structural strength

Papillary Layer of Dermis

• Deep to epidermis

• composed of areolar connective tissue

• capillary beds (feed active blood vessels)

• touch receptors

What is this?

Dermal Papillae

Reticular Layer of Dermis

• Deep and major portion of dermis

• composed of dense irregular connective tissue

• contains hair follicles, nerves, oil glands, sweat glands, heat

• deep sensory sensations

Hypodermis (subcutaneous tissue)

• deep to skin

• adipose and areolar tissue

• ½ of body contains adipose tissue

• Function: energy source, insulation, padding

Hair

• Lanugo - unpigmented hair on infants

• Terminal Hair- pigmented hair of the scalp, eyebrows, eyelids, and pubic hair

• Vellus- thin hair on the rest of the body

Hair Follicle

• Dermal Root Sheath- part of dermis that surrounds the epithelial Root sheath

• Epithelial Root Sheath- with external and internal parts

Hair Root

zone of hair from bulb to skin surface

Root Shaft

protrudes above skin surface

Arrector Pili Muscle

• smooth muscle

• extends from hair follicle to dermal papillae

• muscle contraction causes hair to “stand on end”

• produces ‘goose bumps’

Sebaceous Glands

• produce oily secretions sebum

• prevents drying and inhibits some bacteria

• must empty into hair follicles

Eccrine (merocrine) Glands

• produce sweat containing water and waste

• numerous in palms and soles

Aprocine Glands

• activate at puberty

• open into hair follicles

• odorless but when acted upon by bacteria they then become odiferous

• found in axillae, genitalia, nipples

Merkel Cells

epidermal cells that detect superficial touch

Meissner Corpuscle

• nerve endings in the papillary layer of the dermis that detect touch

• within dermal papillae

Pacinian Corpuscle

nerve endings in the reticular layer of the dermis that detect deep pressure and vibration