PHTY100 Lecture Notes - Lecture 3: Elastin, Dermis, Microvillus
Document Summary
Epithelial tissue: lots of cells, not much extracellular material, all epithelial rest on basement membrane, selective barriers- facilitate or prevent passage of materials, protect underlying tissues against dehydration, chemical and mechanical damage. Simple epithelial: single layer of cells resting on basement membrane, provides surface that substances can move across, squamous (flat), cuboidal (square), columnal (tall) Stratified epithelial: multiple layers of cells resting on basement membrane, designed to resist mechanical abrasion, stratified squamous, cuboidal, columnar, transitional. Epithelial surface specialisations: microvilli: small finger like projections, increase surface area of surface cells, cilia: small hair like projections, wave across surface, keratin: protein that fills the surface cells, makes tissue waterproof. Epidermis: stratified squamous, many layers of cells, deeper cells are living, closer to skin are cornified, avascular. Dermis: deeper network of collagen and elastin fibres, regulation of heat, give toughness and strength. Hypodermis: separates integument form deep fascia and other organs.
