Intergumentary system

Integumentary System

The skin, hair, oil and sweat glands, nails, and sensory receptors

Largest organ of the body

Skin; principal parts are epidermis (superficial) and dermis (deep)

Subcutaneous tissue

Below dermis, not part of skin; anchors dermis, contains lamellar corpuscles

Cells of the epidermis

Keratinocytes, melanocytes, dendritic cells, tactile epithelial cells

Layers of epidermis (deep to superficial)

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (thick skin only), stratum corneum

Stratum basale function

Stem cells divide to produce keratinocytes

Dermis composition

Dense irregular connective tissue with collagen and elastic fibers

Layers of dermis

Papillary (thin collagen, dermal papillae, tactile corpuscles) and Reticular (thick collagen, elastic fibers, adipose, glands, follicles, nerves)

Epidermal ridges

Basis for fingerprints and footprints

Skin color factors

Melanin, carotene, hemoglobin

Tattooing

Pigment deposited in dermis

Body piercing

Jewelry inserted through artificial opening

Accessory structures

Hair, skin glands, nails; from embryonic epidermis

Hair structure

Shaft, root, follicle

Hair follicle associations

Sebaceous gland, arrector pili muscle, hair root plexus

Hair growth cycle

Growth, regression, resting; new hair from matrix cells in bulb

Hair functions

Protection, reduce heat loss, block particles, sense light touch

Lanugo

Fetal hair, shed before birth

Terminal hair

Coarse, pigmented; mostly in males

Vellus hair

Fine; mostly in females

Sebaceous glands

Connected to follicles, absent in palms/soles; produce sebum

Acne cause

Clogged sebaceous glands

Eccrine sweat glands

Widely distributed; open at surface; thermoregulation, waste removal, stress

Apocrine sweat glands

Found in axillae, groin, areolae; open into follicles; activated by stress or sexual excitement

Ceruminous glands

Modified sweat glands; secrete earwax; in ear canal

Nails

Hard, dead keratinized epidermal cells; include plate, free edge, root, lunula, bed, eponychium, matrix

Thin skin

Covers most of body except palms, soles, digits

Thick skin

Covers palms, soles, palmar and plantar surfaces of digits

Functions of skin

Thermoregulation, blood storage, protection, sensation, excretion, absorption, vitamin D synthesis

Thermoregulation

Sweat and blood flow adjustments

Protection

Physical, chemical, and biological barriers

Cutaneous sensations

Touch, temperature, pain

Epidermal wound healing

Stem cells enlarge/migrate; contact inhibition; basal cell division

Deep wound healing phases

Inflammatory (clot, phagocytes), Migratory (fibroblasts, collagen), Proliferative (epithelial growth), Maturation (scab falls, epidermis normal, fibroblasts disappear, vessels restored)

Epidermis origin

Embryonic ectoderm

Dermis origin

Mesodermal cells

Accessory structures origin

Epidermal derivatives

Aging effects

Wrinkling, fat loss, sebaceous gland atrophy, fewer melanocytes and dendritic cells

Integumentary System >>> Consists of skin, hair, oil and sweat glands, nails, and sensory receptors

Largest organ of the body >>> Skin

Two main parts of skin >>> Epidermis (superficial) and Dermis (deep)

Subcutaneous layer (Hypodermis) >>> Deep to dermis; anchors skin; not part of skin; contains fat and lamellar corpuscles

Cell types in the epidermis >>> Keratinocytes, Melanocytes, Dendritic cells, Tactile epithelial cells

Keratinocytes >>> Produce keratin for protection and lamellar granules for waterproofing

Melanocytes >>> Produce pigment melanin for skin color and UV protection

Dendritic cells (Langerhans) >>> Immune response cells

Tactile epithelial cells (Merkel) >>> Work with Merkel discs for touch sensation

Epidermal layers (deep to superficial) >>> Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum (thick skin only), Stratum corneum

Stratum basale >>> Deepest layer, contains stem cells, continuous cell division

Stratum spinosum >>> Provides strength and flexibility

Stratum granulosum >>> Transition layer, keratinization begins, apoptosis

Stratum lucidum >>> Found only in thick skin (palms, soles, fingertips)

Stratum corneum >>> Outermost, dead keratinized cells, waterproof, forms calluses

Keratinization >>> Process of keratin replacing cell contents as they move upward (2–4 weeks)

Dermis composition >>> Dense irregular connective tissue with collagen and elastic fibers

Dermis layers >>> Papillary region and Reticular region

Papillary dermis >>> Thin collagen, fine elastic fibers, dermal papillae, tactile corpuscles

Reticular dermis >>> Thick collagen bundles, coarse elastic fibers, fibroblasts, adipose, hair follicles, nerves, sebaceous & sudoriferous glands

Epidermal ridges >>> Basis for fingerprints and footprints

Skin color pigments >>> Melanin, Carotene, Hemoglobin

Tattooing >>> Pigment injected into dermis

Accessory structures of skin >>> Hair, glands, nails

Hair main parts >>> Shaft, Root, Follicle

Structures with each hair follicle >>> Sebaceous gland, arrector pili muscle, hair root plexus

Hair growth cycle >>> Growth stage, Regression stage, Resting stage

Hair functions >>> Protection from sun, heat loss, entry of particles; sense light touch

Lanugo >>> Fetal hair, shed before birth

Terminal hair >>> Coarse, pigmented (mainly male body hair)

Vellus hair >>> Fine, less pigmented (mainly female body hair)

Sebaceous glands >>> Connected to hair follicles; secrete sebum; absent in palms and soles

Sebum function >>> Moistens hair, waterproofs skin

Clogged sebaceous glands >>> Acne

Two types of sudoriferous glands >>> Eccrine and Apocrine

Eccrine glands >>> Widely distributed; ducts open to skin surface; thermoregulation, waste removal, emotional stress

Apocrine glands >>> Found in axillae, groin, areolae; ducts open into hair follicles; active during stress and sexual excitement

Ceruminous glands >>> Modified sweat glands in ear canal; produce earwax (cerumen)

Nails >>> Hard keratinized epidermal cells on distal digits

Parts of a nail >>> Nail plate, free edge, root, lunula, hyponychium, nail bed, eponychium, matrix

Nail growth >>> From cell division in nail matrix

Thin skin >>> Covers most of body; lacks stratum lucidum

Thick skin >>> Palms, soles, digits; has stratum lucidum

Functions of skin >>> Thermoregulation, blood storage, protection, sensation, excretion/absorption, Vitamin D synthesis

Skin thermoregulation >>> Sweat release and blood flow adjustments

Skin protection >>> Physical, chemical, and biological barriers

Cutaneous sensations >>> Touch, temperature, pain

Epidermal wound healing >>> Superficial wounds; basal cells enlarge, migrate, and divide

Deep wound healing: Inflammatory phase >>> Clot forms, vasodilation, phagocytes clean debris

Deep wound healing: Migratory phase >>> Fibroblasts synthesize collagen and glycoproteins

Deep wound healing: Proliferative phase >>> Extensive growth of epithelial cells

Deep wound healing: Maturation phase >>> Scab falls off, epidermis restored, fibers organized

Epidermis embryonic origin >>> Ectoderm

Accessory structures embryonic origin >>> Epidermal derivatives

Dermis embryonic origin >>> Mesoderm

Skin aging effects >>> Wrinkles, loss of fat, sebaceous gland atrophy, fewer melanocytes & dendritic cells

Age when skin aging starts >>> Late 40s