Flashcards in Lecture 2 - Skin Deck (36):
What are the contents of the skin along its thickness?
Thin epithelium: epidermis
Thicker connective tissue layer: dermis - mesodermal
Hypodermis (subcutis) - connective tissue between skin and deeper structures which is also mesodermal
Appendages (hair, nails, sweat and sebaceous glands)
What are skin epidermal cells made up of?
Stratified squamous keratinised epithelium
What are the layers of epidermis?
Why do burn victims lose lots of fluid?
Skin acts as a barrier for water loss. When it is burned off lots of water is lost from that area.
What is contained in the stratum corneum?
Keratin layer with dead cells embedded in dense protein matrix and spaces are filled with lipids.
What is contained in the stratum lucidum?
Only visible in thicker skin and nuclear outlines breaking down. Flattened cells still visible.
Which layer has spiny connections with desmosomes holding cells together to prevent sloughing off of skin when rubbed together?
Which layer has cells full of keratohyalin granules with lipids released to fill intracellular space preparing to keratinise?
What is contained in the stratum basale?
Layer of columnar or cuboidal rapidly dividing cells which replace epidermis every 3 - 4 weeks
How are thick and thin skin different?
Difference is in corneal layer thickness
What are the layers of dermis and what do they contain?
Papillary dermis contains loose CT as well as capillaries and nerve endings.
Reticular dermis contains dense CT as well as thick collagen fibers aligned along lines of tension (Kraissl lines) This is important for surgery because parallel lines heal faster.
Hypodermis contains loose CT and fat.
What do melanocytes do?
They produce melanin.
Where do melanocytes originate?
They are of neural crest origin. They transfer melanosomes to epidermal cells.
What controls pigmentation of melanocytes?
Pigmentation is under control of light as well as hormones produced by pituitary and adrenal glands.
Diseases of which 2 endocrine organs can cause pigmentation changes in skin?
Adrenal and pituitary glands.
What are some non-epidermal cells in the epidermis?
Specialized nerve endings
Defence related langerhan cells (macrophages)
What gives skin its colour?
Melanin + translucence + capillaries
What glands are located in skin? How do they produce their products?
Merocrine glands (Secretes directly)
Apocrine glands (releases pieces of cytoplasm)
Holocrine glands (cell breaks up and contents released)
What kind of glands are sweat glands?
Merocrine glands (containing ducts)
What kind of epithelium do sweat glands have?
Stratified cuboidal epithelium
What do dark cells of sweat glands produce?
Mucin like secretion
What do apocrine glands produce?
Unknown but likely a milky sexual attractant
What type of glands are sebaceous glands?
Holocrine glands with hair
Where is hair located?
Parts of epidermis root is located in dermis or deeper.
Hair is absent from sole of foot and side of toes
What are the contents of a hair follicle?
Hair + living epithelial cells + surrounding tissue
What is the hair shaft composed of?
What do sebaceous glands produce?
Oily secretion containing antimicrobial, waterproofing, pro and anti inflammatory compounds, and pheromones.
What is the lunula?
The moon shaped part of the base of the nail
What is the nail plate produced from?
Nail germinal matrix (onychostroma) produces the cells that form the nail plate seen as the lunula
What happens as nails are pushed away from lunula?
They thin exposing the nail bed.
What is located under the nail?
Epidermis and dermis (nailbed)
What is the nail plate made of?
Keratin in the dead compacted cells
What is the epithelium under the distal/free edge of the nail called? What does it do?
Hyponychium, it fuses with nail bed epithelium.
What is the grey fusion of nail epithelium with nail bed epithelium called?
What does the eponychium do?
It and the cuticle seal the proximal end of the nail.