BRS Mock 4 derm1, pituitary, airways Flashcards
How does skin development start?
Single layer of cuboidal cells form and make up the surface ectoderm. Secondary layer of squamous non keratinising cells form on top and these cells are know as the periderm.
What do the periderm cells do in early skin development?
Secrete vernix caseosa which is a white waxy protective substance.
What happens later on at week 11 of skin development?
Basal layer of cuboidal cells proliferate to form multilayer intermediate zone. Basal layer of cuboidal cells is now know as the stratum basale.
What happens at week 20 of skin development?
Further differentiation forms spinosum, granulosum, lucidium and corneum.
Where do hair follicles develop from?
Stratum basale.
What are the epidermal ridges that protrude into the dermis known as?
Rete ridges.
What is the superficial layer of the dermis known as?
Papillary dermis.
What are the skin layers from top to bottom?
Epidermis, basement membrane, dermis and subcutaenous fat.
What cells make up the epidermis?
Keratinocytes.
Where does cell division occur in the skin?
Stratum basale.
What are the layers of the epidermis from bottom to top?
Stratum basale, stratum spinosum, stratum granulosum, Stratum lucidum and stratum corneum.
What occur as you go up the layers of the epidermis? And why is this a problem in some diseases?
Differentiation and flattening of cells. This process can be accelerated in skin diseases such as psoriasis.
Why is the stratum lucidum different from other epidermal layers?
Only present in palms and soles.
Describe the stratum lucidum?
Only present in palms and soles. No nuclei or organelles.
What does the keratinocyte cytoskeleton contain?
Actin containing microfilaments. Tublin containing microtubules. Intermediate filaments which are the keratins.
What is the function of desmosomes?
Major adhesion complex. Anchor intermediate filaments to cell membrane and bridge adjacent keratinocytes. Provide strength.
What are gap junctions and what do they do?
Contain intercellular channels. Form connections between cytoplasm of adjacent keratinocytes.
What complex/junction inbetween keratinocytes are essential for cell synchronization and metabolic coordination?
Gap junctions.
What are adherens junctions and what do they do?
Transmembrane structures that engage with the actin skeleton.
What do tight junctions do?
Role in barrier integrity and polarity.
What epidermal cells other than keratinocytes are present?
Melanocytes, langerhans cells, merkel cells and mast cells.
What are merkel cells?
Mechanosensory receptors.
- involved in sensation.
What does the basement membrane contain?
Collagens, laminin and integrins.
What are the most prominent types of collagen in the basement membrane?
IV, VII
Function of rete ridges?
Strength and provides specialised environment for epidermal stem cells.
What are the two main layers that make up the dermis?
Papillary dermis and reticular dermis.
Describe the papillary dermis
Superficial layer of the dermis that is made up of connective tissue and is highly vascular.
Describe the reticular dermis
Dense connective tissue that forms bulk of dermis.
What proteins does the dermis contain?
Collagen, fibrillin and elastin.
What glycoproteins does the dermis contain?
Fibronectin, fibulin and integrins.