Skin and Mucous Membranes Flashcards
What are the functions of skin?
- Protection
- Thermoregulation
- Water regulation
- Sensation
- Absorption
- Storage and synthesis
What are the 3 layers of the skin?
- Epidermis
- Dermis
- Subcutaneous or hypodermis
What are the associated structures of the skin?
- Nails
- Sweat glands
- Sebaceous glands
- Hair follicles
What epithelium is found in the epidermis?
Stratified squamous epithelium:
- Layered
- Flat, scale-like cells
- Basic tissue type (keratinised on skin surface)
Does the epidermis contain blood vessels and nerve fibres?
No
How many layers are there in the epidermis?
4-5 layers
What are the layers of the epidermis?
- Corneum
- Lucidum
- Granulosum
- Spinosum
- Basal
What layer of the epidermis is only present in thick skin?
- Stratum Lucidum
What is the function of basal cells?
- To replace epithelium cells that die and fall away. Most of the thickness of the epidermis, for example, is made of tough cells called keratinocytes. These continuously migrate to the skin surface and fall off, each cell living for 40 days or so. They have to be replaced by mitosis of cells below
What are Langerhans cells?
- Antigen-presenting
What are Merkel cells?
Sensory receptors
What are melanocytes?
- Produce melanin - skin pigments
What are the properties of thick skin and where can it be found?
- Stratum lucidum present
- Thicker stratum corneum
- Palms of hands and soles of feet
What are the properties of thin skin and where can it be found?
- No stratum lucidum
- All strata are thinner
- Covers the rest of the body
What is the dermis?
- Strong flexible connective tissue layer rich in collagen and elastic fibres
What does the dermis contain?
- Fibroblasts
- Macrophages
- Adipocytes
- Nerve endings
- Blood vessels
- Lymphatics
- Glands
- Smooth muscle (some areas)
- Hair follicles
What is the papillary layer of the dermis?
- Projects into intervals between epidermal ridges. Richly supplied with capillaries and nerve endings
What is the reticular layer of the dermis?
Dense connective tissue and fibre components
What is Psoriasis?
- Autoimmune disease
- Cause is uncertain
- Instead of normal cycle of epithelial cells shredding, it starts to have a shorter cycle so cells divide and grow very quickly so epithelium will be very thick
- Scales rapidly fall off
What is Pemphigus?
- Autoimmune disease
- May cause lesions in the mouth, skin or mucous membranes of genital
- Causes spaces in between epithelial cells and they end up rupturing very quickly causing the disease
- Affects quality of life and very painful
What is Vitiligo?
- Loss of skin pigment
- May be autoimmune
process or chemicals/ medication person is exposed to but still unsure - Defect in hormone responsible for production of melanin
What are the 2 most common types of skin cancer?
- Squamous cell carcinoma
- Basal cell carcinoma
What are the risk factors for malignant melanomas?
- UV radiation
- Moles
- Fair skin with freckles
- Sunburn
- Family history
What are mucus membranes?
- Specialised epithelial lining which produces a lubricating fluid containing stick protein mucin which traps microbes and dirt particles and protects any body structure which is continuous with the external environment - present anywhere in the body that is exposed tot the external environment
What is the basic structure of mucous membranes?
Layers:
- Epithelium
- Lamina propria (connective tissue)
What cells are found in lamina propria mucosae?
- Fibroblasts
- Immune cells
- Virtually lacking adipocytes
What is contained within the ECM of lamina propria mucosae?
- Collagen
- Elastic fibres
What epithelium is the traches composed of?
- Ciliated, pseudostratified epithelium and an elastic, fibre-rich lamina propria
What epithelium is the oral mucosa composed of?
- Stratified squamous epithelium
What are the 3 types of oral mucosa?
- Lining
- Masticatory
- Gustatory
What are the functions of the oral mucosa?
- Protection: barrier to micro-organisms
- Sensation: receptors that respond to tough, taste, pain etc
- Secretion: Maintains a moist surface; salivary glands
- Permeability and absorption: a feature utilised in drug delivery
What is lichen planus?
- Autoimmune disease
- Unsure why people get it
- Very itchy skin
What is cystic fibrosis?
- An inherited disorder of ion transport
- Abnormal viscous secretions
- Affects epithelial lining of the respiratory tracts
- Salivary glands may also be affected
