Ch. 5
The Integumentary System
Objectives
• Identify various parts of the integument
• Know the functions of the integumentary system
• Know the structural composition of hair and nails
• Understand how skin disorders like cancer and
burns are classified and what occurs during these
disorders
The Integumentary System
• Includes the skin (integument) and the
accessory organs found within the skin
Skin: Integumentary System
• Functions: prevent dehydration, protect from
injury, serve as defense against microorganisms,
regulate body temperature, make vitamin D,
provide sensation, nonverbal communication
• Structure:
– Epidermis: outer layer, stratified squamous epithelial
cells, no blood vessels, specialized keratinocytes and
melanocytes
– Dermis: deeper layer, support tissues, fibers
Skin: Integumentary System
Epidermis
• Keratinized stratified squamous epithelium
• Cell types
– Regenerative stem cells
– Keratinocytes
– Melanocytes
– Tactile cells
– Dendritic cells
Layers of the Epidermis
• From deep out
– Stratum basale
– Stratum spinosum
– Stratum granulosum
• Keratohyaline granules
– filaggrin
• Lamellated granules
– Stratum lucidum
• Thick skin only
– Stratum corneum
pgbeautygroomingscience.com
Skin Histology
nku.edu
Skin Color
• Melanin
– The more produced, the darker the color
• Hemoglobin
– Reddish – pink skin tones
• Carotene
– Yellow hue to skin
– Concentrates in stratum corneum
Dermis
• Connective tissue layer deep to the epidermis
– Attached to the epidermis via dermal papillae
• Interlocking arrangement with epidermal ridges
• Two layers
– Papillary
• Areolar
– Reticular
• Dense irregular
Accessory Structures of Dermis
• Hair: shaft, follicle
• Smooth muscle: attached to hair follicle, raises
hair to upright position
• Oil glands/sebaceous glands: secretion
moistens and softens skin
Accessory Structures of Dermis (cont.)
• Sweat glands: secrete sweat, help in
temperature regulation
– Apocrine and merocrine
• Blood vessels: supply nutrients, remove waste,
assist in temperature regulation
• Sensory nerve endings: for heat, cold, touch,
deep pressure, vibration
Dermis
healthguide.howstuffworks.com
Hypodermis
• Binds skin to underlying tissue
• Functions as padding and insulation
– Subcutaneous fat
• Readily absorbs drugs given by hypodermic
injection
– Highly vascular
Hair
• Pili (sing. Pilus) are composed of hard, dead
keratinized cells
• Grow from a follicle that is typically found in the
dermis
• Hair divided into three zones
– Bulb which lies in the follicle
– Root
– Shaft
keratin.com
Nails
• Scale-like
modifications of the
epidermis (startum
corneum)
• Dead cells full of
parallel hard keratin
emedicinehealth.com
Skin Disorders
• Skin Cancer
– One of the most prevalent cancers
– UV radiation damages cells
– Three types
• Basal cell carcinoma
– Most common, stratum basale
• Squamous cell carcinoma
– Stratum spinosum
• Malignant melanoma
– Most deadly, melanocytes
metrohealth.org
Burns
• Classified based on depth of tissue involvement
– First degree
• Epidermis
– Red, slight swelling
– Second degree
• Epidermis and into part of the dermis
– Red to white, more painful
– Regeneration of epidermis possible
– Third degree
burn-recovery.org
• Full-thickness, completely through dermis and beyond
– Tan to brown, danger of fluid loss and infection
– Generally require skin grafts to replace dermis and epidermis