The Integumentary System Lesson 1: Integumentary System 22 The Integumentary System Lesson 1: Integumentary System

Lesson Objectives Upon completion of this lesson, students should be able to … Define and spell the terms to learn for this chapter. List and describe the functions of the skin. Discuss the layers of the epidermis. Discuss the layers of the dermis. List and discuss the accessory structures of the skin.

Lesson Objectives Differentiate between basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Explain skin differences of the child and the older adult.

The Integumentary System 4

Skin and Accessory Organs Known as the Integumentary System Sweat glands Sebaceous glands Hair Nails Factoid The skin is the largest organ in the body! Weighs more than 20 pounds (in an adult) Covers 16% of the body Purposes: Protection Regulate temperature Absorption House nerve receptors Secrete fluids 5

Our skin is replaced entirely about every 7 years! Skin Structures Factoid Our skin is replaced entirely about every 7 years! 6

Nail Bed and Structures Factoid Nail beds can tell low oxygen levels in the blood. 7

Critical Thinking Question What functions does the integumentary system serve?

Functions of the Integumentary System Protection Regulation Sensation Absorption Secretion

Primary Function Protection Forms 2-way barrier Keeps out: Pathogens (disease-causing organisms) Harmful chemicals Prevents critical body fluids from escaping the body Protects internal organs 10

Critical Thinking Question What are different ways that this protective function can be compromised? 11

Temperature Regulation Aids in regulation of body temperature To release heat, superficial blood vessels in skin dilate, bringing more blood to surface of skin To conserve heat, superficial vessels constrict, keeping warm blood away from surface Continuous fat layer of subcutaneous layer acts as insulation 12

Sensory Receptors Detect: Are located in skin Temperature Pain Touch Pressure Are located in skin Nerve endings in the middle layer of skin convey messages to the brain and spinal cord 13

Critical Thinking Question What happens to pain detection with a burn? 14

Three Layers of the Skin Epidermis is the thin, outer membrane layer Dermis or “true skin”, is the middle, fibrous connective tissue layer Subcutaneous is the innermost layer, containing subcutaneous tissue 15

Three Layers of the Skin Layers of skin relate to types of injections. 16

Layers of the Epidermis Stratum corneum Outermost layer of skin consisting of dead cells filled with a protein called keratin Forms a protective covering for the body Thickness of the layer depends on the part of the body Stratum lucidum Translucent layer lying directly beneath the stratum corneum In thinner skin, it is often absent Cells in this layer are either dead or dying

Layers of the Epidermis Stratum granulosum Consists of several layers of living cells that become part of the stratum lucidum and stratum corneum Cells actively become keratinized or hardened, after they lose their nuclei Stratum germinativum Made of several layers of living cells, still capable of mitosis, or cell division Most responsible for the regeneration of the epidermis

The Dermis Middle layer of the skin Composed of Connective tissue containing nerves and nerve endings Blood vessels Sebaceous and sweat glands Hair follicles Lymph vessels Further divided into two layers: Papillary layer and reticular layer

The Subcutaneous Layer Composed of subcutaneous tissue Tissue helps support, nourish, insulate, and cushion the skin

Accessory Organs Hair Hair follicles Hair root Hair shaft Fibers composed of the protein keratin Hair formation like the growth in the epidermal layer of skin Melanin gives hair its color Sebaceous glands release sebum into hair follicles 21

Hair turns gray when melanin is no longer produced. Accessory Organs Hair turns gray when melanin is no longer produced. 22

Nails Flat plates of keratin Called nail body Cover ends of fingers and toes Connected to tissue by nail bed Grow longer from the roots Covered and protected by cuticle Free edge is exposed edge Light colored half-moon area at the base is the lunula 23

Nails 24

Fluid-Producing Glands Sweat glands Assist body in maintaining internal temperature Create cooling affect when sweat evaporates Sebaceous glands Oil glands Produce sebum Lubricate the skin surface 25

Questions? 26