chapter 6 integumentary system
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Transcript of 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
Epidermis
• Outermost layer of skin
• Stratified squamous epithelium
• Outermost layers are keratinized• 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
Melanocytes
• Secrete melanin – pigment
• Number of melanocytes is similar in all people
• Darker skin from darker and larger melanin • 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• Blood vessels and nerves
• Hair follicles
• Sweat glands and Sebaceous glands
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
Hypodermis
• Subcutaenous layer – not part of skin
• Adipose Tissue, Areolar Tissue, Blood vessels
• Binds skin to underlying organs• Binds skin to underlying organs
• Adipose insulates the body