Integumentary system Flashcards
Structure of the skin
Epidermis (uppermost), dermis, Hypodermis (areolar or adipose tissue between skin and muscle)
What is the papillary layer?
thin region of loose connective tissue, allows motility of leukocytes, mast and macrophage cells
What is the reticular layer?
thick layer of dense irregular connective tissue, less cells, adipocyte clusters
The dermis
Connective tissue layer beneath epidermis, mainly collagen with elastic and reticular fibres, derived from fibroblast
Where are the accessory organs of the skin contained?
The dermis
Dermal epidermal boundary
Has dermal papillae - facilitates nerve fibres reaching close to surface in sensitive areas
The epidermis
Keratinised stratified squamous epithelium
Layers of the epidermis
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum
Melanocytes
Release melanin - UV absorbent, antioxidant, protects skin from UV damage
Pheomelanin
Red soluble pigment (lips)
Eumelanin
brown/black insoluble pigment
Stratum basale cells
3 cell types
Keratinocytes
Melanocytes
Tactile cells
Deepest layer
Keratinocytes are mitotic and are in the majority
Melanocytes are responsible for skin colour – melanin
Tactile cells are connected to sensory nerves and participate in the sense of touch
Stratum spinosum
Thickest layer of epidermis
Contains keratinocytes and up to 800 dendritic (Langerhans) cells per mm2
Keratinocytes are still mitotic
Cells at the surface of this layer have a more flattened shape
Higher content of keratin
Cells detach from basement membrane and migrate upwards
Stratum Granulosum
Last layer in the epidermis to have cells containing nuclei
Contains 3-5 layers of flat keratinocytes
Keratinocytes are post-mitotic and make a large amount of keratin and glycolipid
Keratin forms filaments that are durable
Glycolipid spreads over the keratinocytes and makes the skin water-resistant
Stratum lucidium
thin translucent zone
only exists in thick skin
densely packed
keratinocytes
Stratum corneum
Most superficial layer of skin
15-30 layers of dead, keratinized cells
High lipid content resulting in a permeability barrier
Cells at the surface flake off
What do nails derive from?
stratum corneum
What do flat or concave nails indicate?
iron deficiency
What are nails composed of?
Dead scaly cells densely packed with keratin fibres
What do clubbed nails indicate?
Long term hypoxia (congenital heart defects)
what are Merocrince sweat glands?
watery perspiration, associated with myoepithelial cells
what are apocrine sweat glands?
ducts lead to follicles, respond to stress and sexual stimulation
what are sebaceous glands?
secrete oil to lubricate skin and hair
what are ceruminous glands?
secrete ear wax
Mammary glands?
only in females, secrete milk
