Skin and Mucous Membrane Flashcards
What are the functions of the skin?
Protection
Thermoregulation
Water regulation
Sensation
Absorption
Storage and synthesis
What are the basic parts of the skin?
Epidermis, dermis, subcutaneous layer
What are the associated skin structures?
nails
sweat glands
sebaceous glands
hair follicles
What is the structure of the epidermis?
Epidermis is made from stratified squamous epithelium which is organised in consistent structure. The cells are flat
No blood vessels in the middle of the epithelium. Only directly underneath the epithelium
Where does the epidermis get oxygen and nutrients?
It gets them from the deeper tissue, the dermis
They are close enough to the blood supply in the dermis to get the adequate oxygen and nutrients for survival
Describe the layers of the epidermis
Stratum basale is the basal layer where cells are synthesised
Stratum spinosum has lots of desmosomes which helps cells attach to each other. The cells shrink causing the desmosomes to become clear and appear prickly
Stratum granulosum cells start to lose their nuclei and cytoplasmic organelles
Stratum lucidum (only in thick skin) no nuclei here, transparent layer
Straum corneum is layers of dead cells which are reduced to flattened squames filled with densely packed keratin, squames on the surface of the layer flake off
Why do cells of the stratum spinosum look like prickles?
Cells shrink slightly during fixation but the desmosomes from neighboring cells remain tightly bound to each other so these connections look like prickles
What are the cells of the epidermis?
Keratinocytes
Langerhans cells
Merkel cells
Melanocytes
What are keratinocytes?
They are also called prickle cells
Most common cell
Make up the majority of cells in the epidermis
What are langerhans cells?
Antigen presenting cells
Present in all layers of the epidermis & in the upper dermis around small blood vessels
What are merkel cells?
Granular basal epidermal cells
Attached to a free nerve ending which finishes at the basal layer where the sensory nerve ending is
Mostly found in thick skin
What are melanocytes?
Produce melanin - has protective function against UV
Present in basal cell layer and the melanin is taken out by the epithelial cells
Present in oral cavity but not active
What causes pigmentation in skin?
activity of melanocytes, not number of them
What is the difference between thick and thin skin?
In thick skin stratum lucidum is present and has more keratin in the stratum corneum. There are also more layers in the epithelium.
In thin skin there is no stratum lucidum and generally layers are thinner
What is the dermis?
a strong connective tissue layer underneath the epidermis