WILD 3580 1st Edition Lecture 36 Outline of Last Lecture I Characteristics of Mammals II Mammalian Evolution III Mammalian Classification Outline of Current Lecture I Skin Glands II Hair Current Lecture I Skin Glands 1 Mammary glands secrete milk to nourish young a Monotremes and cetaceans lack nipples or teats b Location primitively in parallel rows on the abdomen i Some are inguinal posterior part of the abdomen ii Or thoracic anterior c Marsupials circular pattern 2 Sweat glands secrete water as evaporative cooling a Absorbs heat as liquid evaporates b Restricted to certain areas of the body i Where the hair is less dense ex Feet and legs ii Cold adapted aquatic mammals lack sweat glands 3 Sebaceous glands typically associated with hair follicles a Lubricates the hair to avoid brittle hair 4 Scent Glands produce pheromones a Functions Territorial marking Mate attraction Defense Orientation b Examples i Anal glands ex Skunks These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute ii Preputial glands add secretions to the urine for marking ex Rodents and canides II Hair Analogous structures to feathers in which they have evolved independently but share similar functions Pelage entire hair covering composed of dead epidermal cells filled with keratin Molt periodic replacement of the pelage Structures associated with hair follicles o Sebaceous glands o Arrector muscles function to move the hair Some are voluntary movement ex Porcupine Most are involuntary communication thermoregulation o Nerves allows hair to have a tactile function Hair structure 1 Cuticle outermost layer a Usually arranged in cuticular scales variable b Usually no pigments 2 Cortex middle layer a Usually transparent but can have pigments 3 Medulla innermost layer a Typically contain pigments Types of Hair 1 Guard hairs outer layer of the pelage a Awns definitive growth grows to a certain size i Slightly larger at the tip then at the base lie over in one direction b Spines enlarges stiff hairs i Definitive growth ex Quills on porcupines ii Defense c Bristles long hairs with angora growth grows continuously i Ex Mane of horse lions d Wool long soft angora hair i Ex Sheep e Velli very short velvety hairs i Definitive growth ii Embryonic hairs
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