Integumentary System (Chapter 5)

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Functions & Structures

Functions

Protection

Senstation

Temp Regulation

Vitamin D Production

Excretion

Structures

Skin - Is divided into 3 layer (Epidermis, Dermis, and Subcutaneous)

Hair

Nails

Glands

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Epidermis

Avascular - Lack of blood vessels

Epidermal Cells

Keratinocytes - Produce keratin for strength and are most cells

Melanocytes - Contributes to skin colour. Melanin producer.

Langerhans - Part of the immune system

Merkel Cells - Detect light, touch, and superficial pressure

Keratinization - As cells move outward they fill with keratin, die, and become a abrasive resistant and permeable layer.

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Epidermal Strata

Stratum Corneum - Most superficial and consists of cornified cells. Provides structural strength, prevents water loss, resists abrasion.

Stratum Lucidum - Thin, clear zone. Found only in thick skin. Keratohyalin disperses keratin fibers.

Stratum Granulosum -Lamellar bodies release lipid contents. Nucleus and other organelles degenerate and cells die. Produces keratohyalin.

Stratum Spinosum (Basale) - Deepest portion of epidermis.

Keratinization

Psorasis

Malfunction in which the skin cells are replaced every 3-5 days rather than the normal 20-30 days. There is a malfunction in keratinization.

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Thick & Thin Skin

Thick Skin

Has 5 epithelial strata

Found in areas subject to pressure or friction

Finger and foot prints are made when epidermal ridges interlock with dermal papillae

Thin Skin

Has 4 epitelial strata (Lacks stratum lucidum)

Covers most of the body

More flexible

Hair can grow here

Conditions

Callus - An increase in the number of layers in the stratum corneum

Corn - Occurs when hyperkeratosis occurs over a bony prominence (Is cone-shaped with the base extending into the dermis)

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Skin Colour

Pigments

Melanin - Provides protects against UV light. Is a group of chemicals derived from tyrosine. Coloured brown - black/yellowish or reddish.

Melanocytes - Used in the process to create melanin.

Albinism - Deficiency or absence of pigment

Carotene - Yellow pigment from vegetables that accumulates in the stratum corneum, in adipose cells of the dermis, and in subcutaneous tissue.

Cyanosis - Blu colour caused by decrease in blood oxygen content

Blood circulating through the skin impacts the reddish hue, while the thickness of the stratum corneum can create a yellowish colour in thicker areas.

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Skin Cancer

Basal Cell Carcinoma

Is the most common type of skin cancer and affects cells in the stratum basale

Squamous Cell Carcinoma

Affects cells in the stratum spinosum

Melanoma

Arise from melanocytes and is the most deadly type of skin cancer

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2 Layers of the Dermis

Papillary

Areolar with lots of elastic fibers

Dermal papillae, capillary beds

Fingerprints - whorls of ridges

Touch receptors (Meissner), free nerve endings sensing pain

Reticular

Dense irregular connective tissue

Collagen and elastic fibers

Some adipose, hair follicles, nerves, oil glands, ducts of sweat glands, heat sensors

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Subcutaneous Tissue

Located below the skin

Consists of loose connective tissue with collagen and elastic fibres

Cells:

Fibroblasts

Adipose cells

Macrophages - (Also called hypodermis or superficial fascia)

Functions

Energy source

Insulation

Padding

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Hair

Found everywhere except palms, soles, lips, nipples, parts of external genitalia, and distal segments of fingers and toes

Terminal hair - Long, coarse

Vellus hair - short, fine

3 Concentric Layers

Medulla: Central axis

Cortex: Forms bulk hair

Cuticle: Forms hair surface

Hair Structure

Hair follicle

Dermal Root Sheath: Part of dermis that surrounds the epithelial root sheath

Epithelial Root Sheath: With internal and external parts.

External part contains all epithelial parts near surface