BIOL 2030 Lecture Notes - Lecture 21: Stratum Corneum, Integument, Hadrosaurid

• School: York University
• Department: Biology
• Course: BIOL 2030
• Professor: Scott Kelly

Document Summary

Subphylum vertebrata mammalia lecture 21: class mammalia has 29 orders, 3 infraclasses, 1. ~ 250 species: most are located in australia. Viviparous = placental mammals producing young alive rather than laying eggs: placenta = a double-layered spongy vascular tissue, formed from material and foetal tissue in wall of uterus. Integument general: the skin is split into 2 regions, a. epidermis. The epidermis is a stratified squamous epithelium. Cells produced in stratum basale (epidermis grows from) push out towards surface and pass through distinct keratinization stages. Stratum corneum = the outer most region which is composed of dead skin cells. Keratinization helps protect terrestrial organisms from abrasion and bacterial infection. Thinner where protected by hair and thicker where contact and use is increased: b. dermis. Outer papillary layer projecting into epidermis: deeper reticular layer with fibrous connective tissue anchors dermis, attaches to muscle. Blood vessels, nerves and smooth muscle enter/occupy dermis (in particular muscles.