human anatomy, 3rd edition prentice hall, © 2001 the integumentary system chapter 4
TRANSCRIPT
Human Anatomy, 3rd editionPrentice Hall, © 2001
The Integumentary System
Chapter 4
Human Anatomy, 3rd editionPrentice Hall, © 2001
Introduction– Structure
• Epidermis
• Dermis
• Hypodermis
– Functions of the skin
Human Anatomy, 3rd editionPrentice Hall, © 2001
The “Birthday Suit”– Combination of 4 main tissues
• Epithelial – outer layer
• Connective – underlies dermis
• Smooth Muscle – goose bumps
• Nervous – sensory receptors
Human Anatomy, 3rd editionPrentice Hall, © 2001
Functions of the Skin– Protection
– Temperature regulation
– Sensations
– Storage of chemical compounds
– Excretion of wastes
– Synthesis of compounds
– Determines characteristics
Human Anatomy, 3rd editionPrentice Hall, © 2001
Structure of the Skin– 2 principal parts
• Epidermis
• Dermis
– Beneath the dermis
• Subcutaneous layer
Human Anatomy, 3rd editionPrentice Hall, © 2001
The Skin
Human Anatomy, 3rd editionPrentice Hall, © 2001
Epidermis– Stratified squamous epithelium
– Over most of the body it’s thin
– Approximately every month we shed entire skin surface
Human Anatomy, 3rd editionPrentice Hall, © 2001
Epidermis
Human Anatomy, 3rd editionPrentice Hall, © 2001
Epidermis
Human Anatomy, 3rd editionPrentice Hall, © 2001
Replacement of Epidermal Cells– Base of epidermis
• Cuboidal cells divide by mitosis
• New cells are pushed toward surface
– New epidermal cells produce keratin– Cells are flattened as they are pushed upwards– Cells die– Outermost layer
• Cells are dead, filled with keratin
– Takes about two weeks for an epidermal cell to move from the bottom layer to the top
Human Anatomy, 3rd editionPrentice Hall, © 2001
Pigments– Melanin
• Produced by melanocytes
• Skin color varies
• Protect skin from UV rays
– Carotene– Albino
Human Anatomy, 3rd editionPrentice Hall, © 2001
Melanocytes and Melanin
Human Anatomy, 3rd editionPrentice Hall, © 2001
Melanocytes and Melanin
Human Anatomy, 3rd editionPrentice Hall, © 2001
Epidermis and Dermis
– Epidermis is avascular
– Dermis is highly vascular
– Epidermis receives nourishment from dermis
– Cells far away from nourishment die
Human Anatomy, 3rd editionPrentice Hall, © 2001
Dermis
– Largest part of the skin
– Connective tissue
– Contains
• Blood vessels
• Nerves
• Glands
• Hair follicles
Human Anatomy, 3rd editionPrentice Hall, © 2001
Papillary Layer of the Dermis– Most superficial layer– Surface area increased by papillae
• Form fingerprints
– Has lots of sensory receptors Papillary Layer
Human Anatomy, 3rd editionPrentice Hall, © 2001
Papillary Layer
Human Anatomy, 3rd editionPrentice Hall, © 2001
Fingerprints
Human Anatomy, 3rd editionPrentice Hall, © 2001
Deeper Layer of the Dermis– Deeper layer– Dense connective tissue– Contains
• Blood vessels• Glands• Deep pressure receptors
– Attached to underlying organs by the subcutaneous layer
Human Anatomy, 3rd editionPrentice Hall, © 2001
Subcutaneous Layer– Loose connective tissue
• Packed with adipose cells
– Stabilizes position of skin
Human Anatomy, 3rd editionPrentice Hall, © 2001
The Skin
Human Anatomy, 3rd editionPrentice Hall, © 2001
Epidermal Derivatives– Hair
– Glands
– Nails
Human Anatomy, 3rd editionPrentice Hall, © 2001
Functions of Hair
– Protection
– Thermoregulation
– Sensory
– Minor role in humans
Human Anatomy, 3rd editionPrentice Hall, © 2001
Human Anatomy, 3rd editionPrentice Hall, © 2001
Hair Structure
– Shaft
• Superficial portion
– Root
• Below the surface
Human Anatomy, 3rd editionPrentice Hall, © 2001
Hair Structure
– Medulla
• Soft core of hair
– Cortex
• Hard core that gives hair its stiffness
– Cuticle
• Outermost layer of hair
Human Anatomy, 3rd editionPrentice Hall, © 2001
Hair Structure
Human Anatomy, 3rd editionPrentice Hall, © 2001
Hair Structure– Hair develops in follicles
• Downward continuation of epidermis
Human Anatomy, 3rd editionPrentice Hall, © 2001
Growth of Hair– At the base of the follicle, hair papilla
• Contains blood vessels and nerves– Nourishes hair
– Bulb• Contains matrix – epithelial cells responsible for
growth
– Contains melanocytes
Human Anatomy, 3rd editionPrentice Hall, © 2001
Hair Follicle
Human Anatomy, 3rd editionPrentice Hall, © 2001
Arrector Pili– Smooth muscle attaches to follicle– Raises hairs– Response to fright or cold– Function?
Human Anatomy, 3rd editionPrentice Hall, © 2001
Glands– Sebaceous glands
• Connected to hair follicles
• Secrete a waxy, oily substance (sebum)– Blackheads
• Secretion increases at puberty
Human Anatomy, 3rd editionPrentice Hall, © 2001
Sebaceous Glands
Human Anatomy, 3rd editionPrentice Hall, © 2001
Glands– Sweat glands
• Found just about everywhere
• Produce “perspiration”
– Water, salt, met. Wastes
• Function – cooling of the body
Human Anatomy, 3rd editionPrentice Hall, © 2001
Glands– Scent Glands
• Specific type of sweat gland
• Found near hair follicles
– Axillary & genital regions
• Develop at puberty
Human Anatomy, 3rd editionPrentice Hall, © 2001
The Skin with Sweat Glands
Human Anatomy, 3rd editionPrentice Hall, © 2001
Nails– Dorsal surfaces of ends of fingers & toes– Primate feature– Grasping
Human Anatomy, 3rd editionPrentice Hall, © 2001
Nail Structure– Nail body– Free edge– Nail root
• Matrix– Lunula (moon)
Human Anatomy, 3rd editionPrentice Hall, © 2001
Nail Structure
Human Anatomy, 3rd editionPrentice Hall, © 2001
Skin Cancer– Basal Cell Carcinoma
– Squamous Cell Carcinoma
– Melanoma
Human Anatomy, 3rd editionPrentice Hall, © 2001
Basal Cell Carcinoma
Human Anatomy, 3rd editionPrentice Hall, © 2001
Squamous Cell Carcinoma
Human Anatomy, 3rd editionPrentice Hall, © 2001
Melanoma