Integumentary system Flashcards
Primary functions of the skin
Support and protection
Thick and thin skin
Most skin in body is classified as “thin”
Thick skin is only found on the palms of the hands and
soles of the feet
Layers of the skin
Epidermis, dermis, hypodermis (subcutaneous tissue)
Layers of the epidermis
stratum basale
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum
Keratinocytes
cell that makes and stores the protein
keratin
Keratin
fibrous protein that gives hair, nails and skin
their hardness and water-resistant properties
Layers of the dermis
Papillary layer and reticular layer
Papillary layer
(superficial layer) of the dermis projects into the stratum
basale of the epidermis to form finger-like dermal papillae
– Within the papillary layer are fibroblasts, a small number of fat cells
(adipocytes), and an abundance of small blood vessels.
– Contains phagocytes (fight bacteria or other infections), lymphatic capillaries,
nerve fibres and touch receptors (Meissner corpuscles)
Reticular layer
(deep and thicker) has lots of blood vessels and a rich
sensory and sympathetic nerve supply
– The reticular layer appears reticulated (net-like) due to a tight meshwork of
fibres
– Elastin fibres (elasticity) enable movement and collagen fibres (structure and
tensile strength)
Hypodermis
connects skin to underlying fascia (fibrous
tissue) of the bones and muscles
Not strictly a part of the skin, border between the hypodermis and
dermis can be difficult to distinguish
consists of blood vessels, loose, areolar connective tissue
and adipose tissue, which functions as a mode of fat storage and provides
insulation and cushioning for the integument
Pigments
carotene, melanin and haemoglobin
Melanin
produced by cells called melanocytes, which
are found scattered throughout the stratum basale of
the epidermis. The melanin is transferred into the keratinocytes via a
cellular vesicle called a melanosome
