chapter 6 integumentary system

Chapter 6

Integumentary System

Organ • Two or more types of tissues grouped together that perform a specialized task.

Integumentary System • Skin plus accessory structures • Skin is the largest organ in our body

Functions of skin include • Forms protective coating • Retards water loss • Vitamin D synthesis • Temperature control • Houses sensory receptors

3 Layers of Skin • Epidermis • Dermis • Hypodermis • Subcutaneous • Not part of skin

Epidermis • Outermost layer of skin • Stratified squamous epithelium • Outermost layers are keratinized • No direct blood supply – Receives nutrients by diffusion

Stratum Corneum • Outermost layer of epidermis • Tightly packed dead cells • Cells are keratinized • Keratin = water insoluble protein

Stratum Basale • Deepest layer of epidermis • Cells are nourished by dermal blood vessels • Site of cell growth and division • Stratum Basal contains Melanocytes

Figure 6.3 Epidermis of thick skin

Melanocytes • Secrete melanin – pigment • Number of melanocytes is similar in all people • Darker skin from darker and larger melanin granules • Albinism – mutation resulting in no melanin production

Figure 6.4a A melanocyte with melanin granules

Figure 6.5 The red eyes and pale skin reflect the lack of melanin in albinism.

Dermis • • • • • •

Deeper layer of skin Dense irregular connective tissue Contains dermal papillae Blood vessels and nerves Hair follicles Sweat glands and Sebaceous glands

Figure 6.2 Section of skin

Sweat Glands • Secrete sweat onto skin surface • Eccrine glands – respond to elevated temperatures • Apocrine glands - anxiety, sexual arousal, and pain

Sebacous glands • Associated with hair follicles • Secretes Sebum – oil • Keeps hair and skin soft and waterproof

Figure 6.10 Illustration of sweat glands and sebaceous glands.

Hypodermis • • • •

Subcutaenous layer – not part of skin Adipose Tissue, Areolar Tissue, Blood vessels Binds skin to underlying organs Adipose insulates the body

End of Chapter 6