The skin Flashcards
The skin
The largest organ in the body
Known as the integumentary system.
Three main layers
Epidermis - the outermost layer
Dermis - The true skin
Subcutaneous - fatty layer (adipose tissue)
The epidermis
5 layers - Corny Lucy’s Gran Spins Germs
Stratum corneum (Corny) Stratum lucidum (Lucy's) Stratum granulosum (Gran) Stratum spinosim (Spins) Stratum germinativum (Germs)
Stratum corneum
Horny layer
Outermost layer
Flat overlapping keratinised cells (corneocytes)
Cells are dead
Stratum lucidum
Lucid / clear layer - cells are transparent
Only on palms & soles
Cells are dead
Stratum granulosum
Granular layer - keratinisation begins here
Cells begin to fill with keratin granules
Contains living & dead cells
Stratum spinosum
Spiny layer - cells interlock with spiny tendrils (arms)
Cells are living
Melanin granules are present in this layer
Stratum germinativum
Germinating layer - new cells are produced here (mitosis)
Deepest layer of the epidermis
New cells push old cells forward
Journey from germinativum to corneum takes 3-6 weeks (average 28 days)
Key term -Mitosis
Cell division - one cell splits to form 2 identical copies
Melanocytes
Cells which produce melanin (skin pigment / tan)
Found in the stratum germinativum
Key term -Keratinisation
The process through with epidermal cells go from living to dead as the move through the layers of the epidermis & fill with keratin granules.
Keratin
The protein which forms skin, hair & nails
The dermis
The true skin - fibres, nerves, blood vessels & appendages are found here
Has 2 layers - papillary & reticular
The papillary dermis
Lies below the stratum germinativum
Supplies the epidermis with blood (containing oxygen & nutrients).
Sensory nerve endings are found here.
The reticular dermis
Main section of the dermis
Below the papillary layer
Contains collagen & elastin fibres
Skin appendages are found here (sebaceous glands, hair follicles, sweat glands)
Skin appendage - arrector pili muscle
Attaches to the hair follicle and the base of the epidermis.
Contracts to pull the hair upwards to form a ‘goose bump’.