Skin and Integument Histology Flashcards
The integument is an organ consisting of
epithelium, connective tissue, glands and sensory receptors
What are the functions of integument?
barrier and protection against physical, chemical & biological agent
– maintains homeostasis by regulating temperature and water loss
– Tactile, pain, & temperature sensation
What are the two types of skin?
thick and thin
Do thick and thin skin both have epidermis and dermis?
Yes
What type of epithelium is the epidermis?
keratinized stratified squamous epithelium
What type of tissue is the dermis classified as?
CT
Is the hypodermic part of the skin?
No. The hypodermis cushions and insulates the body.
What does the epidermis-dermis junction consist of?
dermal papillae and interpapillary pegs
epidermal protrusions - named interpapillary pegs - into the dermis create dermal papillae
The attachment of the epidermis to the basal lamina is made by what?
hemidesmosomes
The apical border of the epidermis forms what structure?
primary epidermal! ridges
What protrudes in the middle of a primary dermal ridge?
an interpapillary peg of the epidermis
What is the primary role of Dermal papillae – inter papillary pegs?
strengthen grip of epidermis to dermis
What can make the primary epidermal ridges deeper?
mechanical stress
What part of the skin is the source of fingerprint?
Primary epidermis ridges
They are genetically unique – no two people have the same fingerprint (dermatoglyphic – science of fingerprints)
Where are keratinocytes made?
basal layer of skin
What happens when keratinocytes migrate to the skin surface?
They are filled with keratin, die, and eventually slough off
What layer of the epidermis is closest to the dermis?
stratum basale
What kinds of cells are present in the stratum basale?
cuboidal to low columnar cells
Cells in the stratum basale are connected how?
interconnected by desmosomal
junctions.
Are cells in the stratum basale connected to the dermis?
Yes. has hemidesmosomal junctions with basal lamina.
Where does synthesis of lamellar bodies begin?
stratum basale
How many cell layers is the stratum basale?
single layer of mitotically active cells.
Directly on top of the stratum basale is what cell layer? How many cell layers is it?
stratum spinosum, the prickle cell layer
several cells thick
Adjacent cells of the stratum basale are connected by?
desmosomes (spines)
Cells in upper part s. spinosum begin to make what?
karatohyalin granules (which contribute to keratinization)
What cell layer lays directly above the s. spinosum?
the Stratum granulosum (aka the mature synthetic layer)
How many cell layers is the stratum granlosum?
1-3 layers
What do keratohyalin granules contain?
cystine and histidine-rich amino acids & precursors for filaggrin and trichohyalin
Appearance of granules is a clinical marker for final stage of what to occur?
apoptosis
What does Filaggrin do?
aggregates tonofibrils - turning granular cells into cornified cells – a process called keratinization
What is the role of Trichohyalin?
modulates the migration of keratinized cells into the s. corneum (takes 2-6 hrs)
What cell layer is directly superficial to the stratum granlosum?
stratum corneum (the surface layer of the skin)
What is Desquamation regulated by?
proteolytic degradation (serine pepidases) of cells’ desmosomes
What are the major epidermis differences in thin vs. thick skin?
Thin skin has: • no surface ridges • stratum corneum is thinner – typically no s. lucidum sublayer • granule layer absent or poorly defined • presence of pigment in thin skin
T or F. Thin skin has fewer dermal papillae & height of DP is reduced in thin skin
T
Does thick skin have hair?
No. Thin skin has hairs and sebaceous glands, thick skin doesn’t
What are the two components of the water barrier of the skin?
lipid envelope
cell envelope
What is the lipid envelope formed by?
produced by exocytosis of lamellar bodies from s. granulosum cells
lipids use ester bonds to attach to outer surface of cells in s. corneum
What is the cell envelope formed by?
made by cross- linking of insoluble proteins situated on the intracellular membrane of s. corneum cells (more superficial than the lipid envelope)
What proteins are responsible for making the cell envelope?
small proline-rich and larger LORICRIN proteins