Lecture 12 The Integument (Skin) Flashcards
What is a Keratinocyte?
Keratinised Squamous Cell
What is a melanocyte?
Melanin producing cell
What is the epidermis?
Superficial Layer of Stratified Squamous Epithelium consisting mostly of keratinocytes that undergo terminal differentiation.
Also has a basement membrane which is at the junction with the dermis
What is the dermis?
Deeper Layer of Connective Tissue and Skin Appendages
Is hair bearing skin thick or thin?
Thin
What three structures and in what order from superficial to deep make up the skin?
1) Epidermis
2) Dermis
3) Subcutaneous Adipose Tissue
What are four structures and in what order from superficial to deep make up the epidermis?
1) Horn Cell Layer
2) Granular Cell Layer
3) Prickle Cell Layer
4) Basal Cell Layer
What are the four cell types of the epidermis and what is their function?
Keratinocytes - Mechanical Protection and Waterproofing
Melanocytes - UV Light Protection for DNA
Langerhan Cells: Immune Function
Merkel Cells: Sensory Function
Describe the maturation of keratinocytes from the basal membrane to the horn cell layer
1) Basal Cells (Basal Cell Layer)
2) Spinous Cells held together by desmosomes ( Prickle Cell Layer)
3) Granular Cell with Desmosomes (Granular Cell Layer)
4) Cornified Cells with Desmosomes (Horn Cell Layer)
Describe the function of melanin, how they are formed and delivered
Melanin protects DNA against UV light
1) Melanocytes originate from the neural crest (S100 +)
2) The melanin is produced in melanosomes which are found in melanocytes
3) One melanocyte then delivers melanin to 36 keratinocytes via dendrites
4) Keratonocytes then phagocytose the tips of melanocyte dendrites
What causes the difference in skin colour between different individuals?
The number of melanocytes is the same however there is greater activity of melanocytes in darker skin people
What are some features of signs of melanoma
1) High Stage Tumours tend to be very thick
2) Increase in melanocyte numbers
3) Increase in melanocyte pleamorphism (big melanocytes and big nucleus)
4) Melanocytes found in areas other than above the basement membrane (eg melanocytes on the wrong side of the basement membrane
What are Langerhan Cells, where do they originate and what is their function?
- They originate from the bone marrow (CD1 a+)
- They are also dendritic and are antigen presenting cells, immune sentinels surveying the microbiome of the skin
What are Merkel Cells, where do they originate and what is their function?
- Merkel Cells originate from the neural crest
- They are not recognisable in normal sections
- They associate with the sensory nerve endings and mediate tactile touch/sensation
What are the five main components of the dermis?
1) Dense connective tissue (collagen, elastin, extracellular matrix)
2) Nerves, blood vessels, lymphatics, histiocytes, mast cells, plasma cells, lymphocytes
3) Mechanoreceptors, thermoreceptors, Pacinian corpuscules (vibration)
4) Subcutaneous fat
5) Epidermal Appendages, Pilosubaceous Units, Sweat Glands
