I can explain the characteristics of the layers of skin. Objective: I can explain the characteristics of the layers of skin. Agenda Notes over Function and layers of skin Skin Lab Skin Label/Color

The Integumentary System

General Info…….. Skin has 2 layers Epidermis - _______ Sweat glands excrete sweat through pores. urea, salts, and water. Body’s first line of defense! _______________________________________.

The “Birthday Suit” Combination of 4 main tissues: ___________ – outer layer Connective – underlies dermis ___________– goose bumps ___________ – sensory receptors

Functions of the Skin Protection _____________ Sensations __________________ Excretion of wastes _________________ Determines characteristics

Connections Circulatory system: ________________: ____________________ sensory receptors for pain, touch, and temperature

The Skin FG04_02.JPG Title: Components of the Integumentary System Notes: Relationships among the major components of the integumentary system (with the exception of nails, shown in Figure 4-15). Keywords: integumentary system, cutaneous, epidermis, dermis, papillary layer, reticular layer, hair follicles, exocrine glands, nails

Epidermis Outer layer of dead skin cells called cuticle . ______________________. “Ashiness” is caused by this layer of dead skin cells being very rough and raggedy. DUST you see around is made up of dead skin cells! Under the cuticle is another layer of living _____________ cells that make up the rest of the epidermis.

Epidermis and Dermis Epidermis is ____________ (no blood vessels) Dermis is highly ________________ (has blood vessels) Epidermis receives nourishment from dermis Cells far away from nourishment die

Epidermis FG04_03.JPG Title: The Structure of the Epidermis Notes: A light micrograph through a portion of the epidermis, shows the major stratified layers of epidermal cells. Keywords: epidermis, structure, layers, stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum germinativum, dermis

Organization of the Epidermis Figure 5–2

Cells of the Epidermis _______________: contain large amounts of keratin the most abundant cells in the epidermis

Thin Skin Covers most of the body ___________________

Thick Skin Covers the palms of the hands and soles of the feet ____________________

Structures of the Epidermis The 5 strata of keratinocytes in thick skin Figure 5–3

Layers of the Epidermis From basal lamina to free surface: stratum germinativum _______________ stratum granulosum stratum corneum

Stratum Germinativum The “germinative layer”: has many germinative (stem) cells or basal cells is attached to basal lamina by hemidesmosomes ________________________________________________________________________

Structures of Stratum Germinativum __________________(e.g., fingerprints) _______________(tiny mounds): increase the area of basal lamina strengthen attachment between epidermis and dermis

Ridges and Ducts Figure 5–4

Cells of Stratum Germinativum Merkel cells: _____________________ ________________(trigger nervous system) Melanocytes: ______________________ scattered throughout stratum germinativum

Stratum Spinosum The “___________”: produced by division of stratum germinosum 8–10 layers of keratinocytes bound by desmosomes ________________________________(spiny)

Cells of Stratum Spinosum Continue to divide, increasing thickness of epithelium Contain ______________, active in immune response

Stratum Granulosum The “_______________” Stops dividing, starts producing: _____________: a tough, fibrous protein makes up hair and nails

Cells of Stratum Granulosum Produce protein fibers ______________ Create tightly interlocked layer of keratin surrounded by keratohyalin

Stratum Lucidum The “___________”: found only in thick skin covers stratum granulosum

Cells of Stratum Lucida Flat ________ ___________

Stratum Corneum The “_____________”: ________________ 15 to 30 layers of keratinized cells water resistant _________________________

Keratinization The formation of a layer of dead, protective cells filled with keratin __________________________________________________________________

Skin Life Cycle It takes 15–30 days for a cell to move from stratum germinosum to stratum corneum

Dermis Thick layer under the epidermis _______________________________ Oil glands Sweat glands Hair follicles Fat tissue Nerves Connective tissue

Dermis The dermis has several important characteristics: is composed of connective tissue containing collagen and elastic fibers ____________________ the outer ______________consists of areolar connective tissue containing thin collagen and elastic fibers, __________________(including capillary loops), corpuscles of touch and free nerve endings

Dermis The deeper _____________________consists of dense irregular connective tissue containing collagen and elastic fibers adipose cells, hair follicles, nerves, sebaceous (oil) glands, and sudoriferous (sweat) glands Striae or stretch marks can appear if the skin is stretched too much

Hypodermis - called subcutaneous, Sub-Q or superficial fascia - ____________________________ - ______________________________ - common site for injection

Hair (pili) - ________________________________ - hair root nerve plexus for touch - normal hair loss in adult 70-100 hairs/day

Hair anatomy: - composed of dead columns of keratinized cells. - shaft: ____________________ - root: _____________________