WILD 3580 1st Edition Lecture 36Outline of Last Lecture I. Characteristics of MammalsII. Mammalian Evolution III. Mammalian Classification Outline of Current Lecture I. Skin GlandsII. Hair Current LectureI. 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 pattern2. Sweat glands- secrete water as evaporative cooling a. Absorbs heat as liquid evaporates b. Restricted to certain areas of the bodyi. 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. Examplesi. 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 follicleso 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 structure1. Cuticle- outermost layera. Usually arranged in cuticular scales (variable) b. Usually no pigments2. Cortex- middle layera. Usually transparent but can have pigments 3. Medulla- innermost layera. Typically contain pigments - Types of Hair1. 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 growthii. Embryonic
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