the skin 1 Flashcards
What is a keratinocyte?
keratinised squamous cell
What is a melanocyte?
melanin producing cell
What is the epidermis?
superficial layer of keratinocytes
What is the dermis?
deeper layer of connective tissue and skin appendages
What are exocrine glands?
glands with ducts or secretion onto surfaces
What are endocrine glands?
glands secreting directly into blood
What are glands formed from?
specialised cuboidal/columnar epithelial cells
What are the types of exocrine secretion?
- merocrine
- apocrine
- holocrine
Describe merocrine secretion
- exocytosis via vesicles
- no damage to cell itself
Describe apocrine secretion
- apical part of cell accumulates secretion and then pinched off
- cell survives
Describe holocrine secretion
- rupture of cell membrane
- cell dies and becomes secretory product
What are cytokeratins?
intermediate filaments of epithelia
What are the 3 layers of skin?
- epidermis
- dermis
- subcutaneous adipose tissue
Describe the epidermis
- epithelium
- ectodermal origin
Describe the dermis
- connective tissue
- mesodermal origin
What is the Meissner corpuscle for?
fine touch sensation
What is the Pacinian corpuscle for?
vibration sensation
What is hairless skin called?
glabrous skin
Which 5 layers compose the epidermis?
- horn cell layer
- granular cell layer
- prickle cell layer
- basal cell layer
What are the 5 layers of the epidermis each for?
- horn cell layer (waterproofing)
- granular cell layer (filaggrin)
- prickle cell layer (mechanical strength)
- basal cell layer (replenishing)
What cell types are found in the epidermis?
- keratinocytes
- melanocytes
- langerhans cells
- merkel cells
What are langerhans cells for?
immune function (sentinel cells)
What are merkel cells for?
sensory function (light touch)
Why are cytokeratins important in diagnosis
individual organs have very specific cytokeratins (so do immunohistochemistry on malignant cells and you can tell where they are from)
What is the largest organ of the body?
skin
What percentage of bodyweight is skin, and how many kilos?
- 5kg
- 15% of bodyweight
What surface area does skin cover?
2 m^2
Where do you find glabrous, hairless skin?
- fingers
- palms
- toes
- soles
- lips
- labia minora
- glans penis
What is the epidermis composed of?
keratinocytes undergoing terminal differentiation
What is at the junction between the epidermis and dermis?
basement membrane (collagen layer)
What kind of epithelium is found at the epidermis?
keratinising stratified squamous epithelium
How can you recognise squamous desmosomes?
they have prickles
How do melanocytes deliver melanin?
delivers melanin to 36 keratinocytes via dendrites
