Chapter 10
Skin Deep
© 2009 Delmar, Cengage Learning
Functions of the
Integumentary System
• The integumentary system consists of
skin and its accessories .
– Accessory organs include glands, hair, fur, wool,
feathers, scales, claws, beaks, horns, hooves, and
nails.
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Functions of the
Integumentary System
• Skin is largest organ system in the body
• Skin plays a role in
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protecting animals from infection,
waterproofs the body,
prevents fluid loss,
provides species-specific coloration/ camouflage,
Maintains and regulates body temps
and provides a site for vitamin D synthesis.
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Skin
• Skin covers the external surfaces of the
body and is composed of epithelial tissue.
– The combining forms for skin are cutane/o, derm/o, and
dermat/o.
– The suffix -derma also means skin.
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Skin Layers
• Epidermis
– most superficial layer
• Dermis
– middle layer that
contains blood and
lymph vessels, nerve
fibers, and accessory
organs
• Subcutaneous
layer
– deepest layer that
contains connective
tissue
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Skin
• Skin is made up of three layers:
– Epidermis
• Epithelial tissue
• 3 – 5 distinct cell layers depending on species or
location on body
• Melanin is found in one of these layers (pigment /
skin color)
• “Thick skin” found on areas of hard usage such as
paw pads, dorsal neck, dorsal thorax, rump
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– Dermis
• Connective tissue containing blood vessels, nerves,
lymph vessels, tiny muscles attached to hair
follicles (arector pili)
• Exocrine glands and touch receptors (called
Pacinian Corpuscles) for sensations such as hot,
cold, touch, pain
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- Hypodermis
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Made up of loose connective tissue and fatty tissue
Allows the skin to slide over structures without tearing
Subcutaneous
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Glands
• Skin glands may be either sebaceous, sweat, or musk
glands.
• These glands are exocrine glands
– Sebaceous glands secrete an oily sub-stance called sebum.
• Hair covered areas / attached to hair follicles
• Oily, waxy, waterproofing
– Sweat glands secrete sweat.
• Also called sudoriferous glands
• Ceruminous glands = Earwax is sebum + dead cells
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Hair
• Hair is rodlike fibers made of dead
protein cells filled with keratin.
– Combining forms for hair are pil/i, pil/o, and trich/o.
– Hair follicles are sacs that hold the hair fibers.
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Telogen Effluvium
Hair has Growth Cycles
Anagen Phase – active growth, hair is lengthening
Catgen Phase – transitory phase
Telogen Phase – hair stops growing / resting phase
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Types of hair
1. Primary or guard hairs
 Straight or arched; thicker and longer than secondary hairs
2. Secondary or wool-type hairs
 Softer and shorter than primary hairs; wavy or bristled in the dog;
predominant hair type in species with wool-type coats
3. Tactile hairs
 Contain numerous sensory endings : probes and feelers for the
animal
 Commonly known as whiskers; also mixed intermittently throughout
the hair coat
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Nails, Claws, and Hooves
• The distal phalanx of
animals is covered by
nails, claws, or hooves.
– Nails and claws are keratin
plates in dogs and cats.
• Combining form is onych/o.
– Hooves are the horny covering
of the distal phalanx in
ungulates such as horses,
ruminants, and swine.
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Pads
• Pads are thick areas of keratinized epithelium.
– Dogs and cats have digital pads and metacarpal and metatarsal pads.
• Livestock have walls, soles, and bulbs.
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Paw Pads…if you ever wondered
 Thick layers of fat and connective tissue with exocrine
sweat glands and touch receptors
 Outer surface is the toughest and thickest skin in the
body
 Often pigmented; composed of all five epidermal layers
Stratum corneum (top layer) is thicker than all other layers
combined
 Conical papillae can be seen covering entire pad
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Planum Nasale
•Composed of three
epidermal layers
•Polygonal plaques
separated by grooves in
the epidermis
•Top of the nose in cats,
pigs, sheep, and dogs
•Planum nasolabiale: the
muzzle of cows and
horses
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Terms
• Alopecia
• Pruritis
• Keratinization
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Alopecia
• Hair loss
– Several causes
• Hypothyroidism
• Nutritional
• Skin parasites
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Pruritis
• Itching
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Allergies
Skin parasites
Behavioral
Bacterial
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Keratinization
• Hyperkeratosis
-idiopathic (unknown cause) condition
-characterized by the excessive formulation of nasal or
footpad keratin. -common in older dogs.
-thickened, hard, dry keratin accumulates on the top of the
nose, footpads, or both.
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• Mange
Mange Mites
– Inflammation of the dermis and epidermis
• Causes pruritus and alopecia
• Hyperkeratosis
• Bacterial infections
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Caused by Mites
Chyletiella
Sarcoptic Mange Mite
Demodectic
Ear Mite
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Skin Scraping
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Medical Terms for the
Integumentary System
• Additional terms for integumentary system
tests, pathology, and procedures can be
found in the text.
• Review StudyWARE to make sure you
understand these terms.
© 2009 Delmar, Cengage Learning
© 2009 Delmar, Cengage Learning