Lecture 1 Flashcards
What does the Integumentary system include?
Skin and accessory structures
What are the 3 primary layers of skin?
Epidermis and Dermis (Cutaneous) and Hypodermis (Subcutaneous)
Features of epidermis
Stratified (stacked) layer, Mostly keratinocytes, Avascular, Constantly replenishes (shedding)
Features of Dermis
Protein fibres (collagen + elastin) for strength, Vascular (nourishes epidermis)
Features of Hypodermis
Adipose tissue
Types of Epithelia with descriptions
Simple and Stratified: Squamous (flat like scales), Cuboidal, Columnar
What is the predominant cell type in the epidermis?
Keratinocytes
Stratified squamous epithelium
Describe the Stratum corneum
Spiky layer- made of dead, dried out cells without nuclei
Describe the Stratum granulosum
Granular layer- contains granules that promote dehydration of the cell and cross linking of keratin fibre, Waxy material is secreted into the intracellular spaces to make watertight barrier
Describe the Stratum spinosum
Spinous or prickly cell layer- Desmosomes link the cells together, Cells become increasingly flattened as they move upward, Contains dendritic cells
Describe the Stratum basale
Basal layer- Columnar regenerative cells, As the basal cell divides, daughter cell migrates upwards to replenish above layer
What is the name of the layer found only in thick skin?
Stratum lucidum
Difference between Desmosomes and Hemidesmosomes
Desmosomes anchor adjacent/neighbouring cells in ALL of epidermis. Hemidesmosomes anchor stratum basale to the dermis
Acronyms for Thick and Thin skin
Thin- Come Get Some Maccas (4 layers)
Thick- Come Lets Get Some Maccas (5 layers)
Characteristics of thick skin
Palms of hands and soles of feet, No hair and contains an extra ependymal layer
Dermis layers
PR- Papillary layer and Reticular layer
Dermis characteristics
Below the epidermis and anchored by hemidesmosomes, Not shed
Papillary layer
Consists of highly vascularised tissues (for nourishment)
Reticular layer
Mesh-like structure of collagen and elastic fibres (for strength)
What is common between Reticular and Papillary layer
Both contain blood vessels, lymphatics, sensory nerve fibres and accessory structures
What is a plexus
A network of blood vessels OR nerves
Describe the Cutaneous Plexus
Network of blood vessels present at the dermis/hypodermis junction and Supplies the hypodermis and deeper dermis including capillaries for sweat glands and hair follicles
Describe the Subpapillary Plexus
Branches from the cutaneous plexus and is deep to the papillary layer of the dermis, Network of blood vessels that provide O2 and nutrients to the upper dermis and epidermis
Hypodermis Characteristics
Subcutaneous layer so is not part of the skin, Is dominated by adipocytes that produce subcutaneous fat which stores energy and provides insulation , is a common site for injections using hypodermic needles
