chapter 6 integumentary system. organ two or more types of tissues grouped together that perform a...
TRANSCRIPT
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