CAM101 Lecture 20: Integumentary System I
Part 1 Introduction and Overview of the Layers of the Skin
Learning Objectives
• Describe the structure, function and location of the four primary tissue types within the layers
of the skin
Integumentary System - Skin
• Arranged into an organ (epidermis + dermis = skin), while together with its accessory
structures (hair follicles, adipose tissue, sweat glands, nails etc.) form the integumentary
system.
Tissues of the Integumentary System
Skin
• Epidermis - epithelium (E)
• Dermis - connective tissue (CT)
Subcutaneous layer
• Hypodermis (CT)
Accessory structures of skin
• Hairs (E)
• Sebaceous glands (E)
• Sensory receptors (N)
• Arrector pili muscles (M)
• Sweat glands (E)
• Blood vessels (E-CT-M-N)
Layers and Tissues of the Skin
{Also what colour is shown with a trichrome stain}
Epidermis {Red}
• Stratified squamous keratinised epithelium
Dermis {Purply blue}
• Papillary layer (Papillary dermis)
o Loose CT
• Reticular layer (Reticular dermis)
o Dense irregular CT
*Hypodermis (Subcutaneous tissue/subcutis) {White}
• Adipose and dense irregular CT
Part 2 Epidermis and keratinocytes
Learning Objectives
• List and describe the layers of the epidermis, including major features of keratinocytes within
each layer and the process of keratinisation
Epidermis
A layer of stratified squamous keratinised epithelium sitting on a basement membrane.
The epithelium can be sub-divided into 4-5 layers from the base to the free surface:
• Stratum basale (B)
• Stratum spinosum (S)
• Stratum granulosum (G)
find more resources at oneclass.com
find more resources at oneclass.com
• Stratum lucidum** (L)
• Stratum corneum * (C )
*Dead layers of keratinocytes
**Only visible in thick skin
Keratinocytes - Epithelial Cells of the Skin
• The cells of the epidermis layer are called keratinocytes
• The cells at the surface are removed by abrasion
• The shape of the cells changes as they progress through
The layers towards the surface
• Cuboidal, irregular spiny, flattened with granules and then squamous (remember we classify
epithelia by the shape of the surface cells)
Life cycle of a keratinocyte
• They undergo keratinisation
o Gives rise to cells that have a great resistance to abrasion
• The keratinocytes fill with tonofilaments (intermediate filaments) and keratohyalin granules
and in addition they secrete a glycolipid (lamellar bodies) that waterproofs the skin by coating
the outside of each cell (provide a protective layer)
• The cells of lucidum and corneum are dead cells forming plates of keratin
Stratum Basale or basal layer
• Deepest layer
o Cuboidal or low columnar
• Many cell junctions
o Hemidesmosomes
o Desmosomes
• Cells may contain melanin granules
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Part 1 introduction and overview of the layers of the skin. Learning objectives: describe the structure, function and location of the four primary tissue types within the layers of the skin. Integumentary system - skin: arranged into an organ (epidermis + dermis = skin), while together with its accessory structures (hair follicles, adipose tissue, sweat glands, nails etc. ) form the integumentary system. Skin: epidermis - epithelium (e, dermis - connective tissue (ct) Sensory receptors (n: hairs (e, arrector pili muscles (m, blood vessels (e-ct-m-n) {also what colour is shown with a trichrome stain} Dermis {purply blue: papillary layer (papillary dermis, loose ct, reticular layer (reticular dermis, dense irregular ct. *hypodermis (subcutaneous tissue/subcutis) {white: adipose and dense irregular ct. List and describe the layers of the epidermis, including major features of keratinocytes within each layer and the process of keratinisation. A layer of stratified squamous keratinised epithelium sitting on a basement membrane.
