ZOO 2090 Lecture Notes - Lecture 5: Desiccation, Placodermi, Sarcopterygii

• School: University of Guelph
• Department: Zoology
• Course: ZOO 2090
• Professor: Jinzhong Fu

Document Summary

Integument/skin is a composite organ at the interface between the organism and its environment: varies greatly depending on the habitat of the organism. Epidermis: dermis (cid:198)note: all vertebrates have an epidermis and dermis, but not all vertebrates have a hypodermis, hypodermis (cid:198)note: (cid:858)hypo(cid:859) (cid:373)ea(cid:374)s u(cid:374)der(cid:374)eath. Ectoderm forms epidermis, mesoderm (dermatome) forms dermis: pigment cells (chromatophores) migrate from the neural crest (dorsal side of embryo) Epidermis: may be one or more layers. Hypodermis: beneath the dermis, may not be present(cid:198)not all species have it, the best example is a polar bear(cid:198)fat cells are used for insulation against the cold, often contains fat cells for insulation. Functions of integument: physical barrier, respiration (o2 exchange for entire body happens through the integument system), excretion (co2, urea), osmotic regulation. Thermoregulation (on land: colours and odours used in courtship or defense. Variation across groups: number and complexity of glands, differentiation of the stratum corneum, many unicellular and some multicellular mucous glands(cid:198)mucus.