Chapter 5 Flashcards by Liz Aguiar

4 principal cells of epidermis

Keratinocytes
Melanocytes
Intraepidermal macrophages
Tactile epithelial/ merkel cells

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Layers of epidermis

Stratum basale
Stratum spinosum
Stratum granulosome
Stratum lucidunn
Stratum corneum

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Callus

Abnormal thickening in stratum corneum

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Keratinization

Cells move from one epidermal layer to the next and accumulate more keratin and then undergo apoptosis

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Keratohyalin

Darkly staining granules of protein
Stratum granulosom

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Dermis

Deeper part of the skin
Dense irregular connective tissue with collage and elastic fibers

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Carpuscle

Nerve endings sensitive to touch

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Free nerve ending

Dendrites that lack any apparent structural specialization

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Epidermal ridges

Ridges and grooves on palms, fingers, soles and toes

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Hair pili

Present on most skin except thick
Protects head from injuries to scalp and uv

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Hair shaft

Superficial portion, projects above the skin

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Hair root

Deep to shaft, penetrates dermis and sometimes subcutaneous

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Hair root and shaft have 3 concentric layers of cells

Inner Medulla
Cortex
Cuticle

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Hair follicle

Surrounds root of hair

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Dermal root sheath

Dense dermis surrounding hair follicle

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Hair bulb

Base of each hair follicle and surroundes dermal root sheath

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Arrector pili

Smooth muscle that’s extends from superficial dermis of skin to dermal root sheath

Hair root plexus

Formed from densities surround hair follicles

Sebum

Secreted by sebaceous glands
Protects hair from drying out and keeps skin moist

2 types of sudoriferous glands

Eccrine
Apocrine

Thermoregulation

Homeostatic regulation of body temperature

Thermoregulatory sweating

Role of eccrine sweat glands helping body achieve thermoregulation

Insensible perspiration

Sweat that evaporates from skin before it is perceived as moisture

Sensible perspiration

Sweat that is excreted in large amounts and seen as moisture on skin

Ceruminous gland

Modified sweat gland in ear

Cerumen

Combination of ceruminous and sebaceous gland secretion

Nails

Plates of tightly packed, hard, dead keratinized epidermal cells that form a clear, solid covering over dorsal surface of distal portion of digits

Nail body

Visible portion of nail, appears pink because of blood flow in underlying capillaries

Free edge

Extends past distal end of digit White because there are no underlying capillaries

Nail root

Portion buried in fold of skin Proximal end of nail body

Lunula

White crescent shaped area proximal to end of nail body

Hyponychium

Junction between the free edge and skin of fingertip Secures nail to finger tip

Nail bed

Skin below nail plate

Eponychium

Cuticle Narrow band of epidermis that extends from and adheres to margin of nail wall

Nail matrix

Epithelium proximal to nail root

Function of nails

Protection Support and counter pressure Helps in grasping and manipulation small objects

Thin skin

Hairy skin Found everywhere but palms and feet

Thick skin

Hairless skin Palms, fingers and feet

Function of skin

Thermoregulation Blood reservoirs Protection Cutaneous sensation Excretion and absorption

Vitamin

Activated by uv Calcitriol is most active form and used in many places