Download Skin functions and structure

Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 4
Skin structure and functions
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Integumentary System
 Skin (cutaneous membrane)
 Skin derivatives
 Sweat glands
 Oil glands
 Hairs
 Nails
 skin, hair and nails
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Skin Functions
• Protects deeper tissues from:
• Mechanical damage
• Bumps, cuts
• Chemical damage
• Acids, bases
• Bacterial damage
• Infections, disease
• Thermal damage
• Heat, cold
• Ultraviolet radiation
• Harmful sunlight
Skin Functions
• Desiccation
• Water loss
• Aids in heat regulation
• Capillaries open to release, or close to hold in
heat carried by blood
• Sweat glands activate to release heat
• Aids in excretion of urea and uric acid
• Perspiration
• Synthesizes vitamin D
• Sunlight converts cholesterol to vitamin D
Skin Structure
 Epidermis – outer layer
 Stratified squamous
epithelium
 Often keratinized
(hardened by keratin)
 Dermis
 Dense connective tissue
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Layer of Epidermis
• Stratum basale
• Cells undergoing mitosis
• Lies next to dermis
• Deepest cell layer
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum
• Occurs only in thick skin
• Palms, soles
• Stratum corneum
•
•
•
•
Shingle-like dead cells
20 – 30 cell layers thick
Shed constantly
New epidermis every 25-45 days
Skin Structure
 Deep to dermis is
the hypodermis
 Not part of the
skin
 Anchors skin to
underlying
organs
 Composed
mostly of
adipose tissue
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Melanin
 Pigment (melanin) produced by
melanocytes
 Color is yellow to brown to black
 Melanocytes are mostly in the
stratum basale
 Amount of melanin produced
depends upon genetics and
exposure to sunlight
 Freckles and moles are seen
when melanin is concentrated.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Dermis
Dense connective tissue
Dermis
 Two layers
Papillary layer
 Uper dermal region
 Projections called
dermal papillae
 Pain receptors
 Capillary loops
Reticular layer
 Blood vessels
 Glands
 Nerve receptors
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 4.13a
Skin Structure
Figure 4.4
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings