Chapter 10 Skin Deep

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.

Functions of the Integumentary System Skin is largest organ system in the body Skin plays a role in 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.

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.

Skin Layers Epidermis Dermis Subcutaneous layer most superficial layer middle layer that contains blood and lymph vessels, nerve fibers, and accessory organs Subcutaneous layer deepest layer that contains connective tissue

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

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

Hypodermis Made up of loose connective tissue and fatty tissue Allows the skin to slide over structures without tearing Subcutaneous

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

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.

Telogen Effluvium Hair has Growth Cycles Anagen Phase – active growth, hair is lengthening Catgen Phase – transitory phase Telogen Phase – hair stops growing / resting phase

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 Tactile hairs Contain numerous sensory endings : probes and feelers for the animal Commonly known as whiskers; also mixed intermittently throughout the hair coat

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.

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.

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

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

Terms Alopecia Pruritis Keratinization

Alopecia Hair loss Several causes Hypothyroidism Nutritional Skin parasites

Pruritis Itching Allergies Skin parasites Behavioral Bacterial

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.

Mange Mites Mange Causes pruritus and alopecia Hyperkeratosis Inflammation of the dermis and epidermis Causes pruritus and alopecia Hyperkeratosis Bacterial infections

Caused by Mites Chyletiella Sarcoptic Mange Mite Demodectic Ear Mite

Skin Scraping

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.