Lecture 17- Skin Flashcards
What are the 2 layers of skin
Epidermis (epithelium), dermis (connective tissue)
Identify layers of skin
How do you identify the epidermis
It’s always darker than the dermis
What does the epidermis begin as
Surface ectoderm
Surface ectoderm forms a keratinized
_______
Stratified squamous epithelium
Epithelial cells are shed throughout life _______ while mitosis adds new epithelial cells ______
Apically, at the base
Epidermis is ______, gets nutrients from _____
Avascular, diffusion
What are the 4 major layers of epidermis from superficial to deep
Stratum corneum, Stratum granulosum, Stratum spinosum, Stratum basale
Stratum corneum:
▪ Anucleate, dead cells
▪ Tough, water-resistant barrier
Stratum granulosum:
Granular cells toughen keratin &
form lipid-based water barrier
Stratum spinosum:
“Prickle cells” are linked by lots of
desmosomes and intermediate
filaments made of keratin protein
Stratum basale:
Basal cells divide (renew epithelium/ single layer)
What does the keratinocyte do
Forms a barrier
What does a melanocyte do
Forms pigment
What does a langerhans cell do
Immune defense
What does a Merkel cell do
Sensory perception
Keratinocyte derives from where
Surface ectoderm
Acidophilic cytoplasm reflects accumulated keratin (intermediate) filaments visible in TEM as ______
Tonofibrils (T)
Tonofibrils anchor into _____
Desmosomes
Autoimmune destruction of desmosomes may result in ______
Clear, flaccid blisters – pemphigus vulgaris
Melanocyte function
Protect basal cells by donating pigment
How do you identify a melanocyte
Colorless cytoplasm in stratum basale
Melanocytes come from embryonic _________ and migrate and populate _____
Neural crest cells, stratum basale
Identify arrows
Basal cells absorb ______, which shield the nucleus from UV damage
Melanosomes
Melanocytes give pigment to how many keratinocytes (basale cells)
Roughly 50
Melanocytes contain ______ that contain _______
Melanosomes, melanin
Skin color due to quantity and content of _______
Melanosomes
Langerhans cells are what? Found where?
Special immune cells, found in epidermis (spinosum)
Langerhans cells function as a specialized ______
Antigen-presenting cell
How do you identify a langerhans cell
Clear cytoplasm
Where does a langerhans cell come from
Hematopoietic cells in liver/bone marrow
What is an endocytic vesicle that helps break down viruses in the cytoplasm of langerhans cells
Birbeck granule
Merkel cells have a ____ function
Sensory
How do you identify a merkel cell
Clear cytoplasm, restricted to stratum basale
Where are there high concentrations of Merkel cells
Specialized touch areas (fingertips)
What is contained in a Merkel cell
Dense granules filled with neurotransmitter
Merkel cells have what origin
Surface ectodermal origin
Cell + nerve process = ______ (sensory receptor)
Merkel disk
Identify
Identify
Identify
List the 3 skin cancers in order of most common/ less likely to spread to less common/ more likely to spread
Facts about basal cell carcinomas
Originates from basal cell
▪ Flatness reflects deep origin
(stratum basale)
▪ Not usually pigmented
▪ Keratin biomarker
▪ Initially anchored by
hemidesmosomes
Facts about squamous cell carcinomas
▪ Originates from “prickle cell”
▪ Raised bump reflects superficial
origin (stratum spinosum)
▪ Not usually pigmented
▪ Keratin biomarker
▪ Initially anchored by
desmosomes
Facts about melanomas
▪ Originates from melanocyte
▪ Flatness reflects deep origin
(stratum basale)
▪ Pigmented (melanosomes)
▪ Vimentin biomarker
▪ No desmosomes or
hemidesmosomes
The dermis is deep to what
The epidermis
Dermis derives from ________
Mesenchyme
What are the 3 sources the dermis is derived from
Neural crest, dermatome, parietal mesoderm
2 facts about the dermis
Vascularized, contains fibrous connective tissue
What is the dermal papilla
What is contained in the papillary layer of the dermis & what is it for
Fine fibers – loose connective tissue, nourish, support & defend epidermis
What is contained in the reticular layer of the dermis & what is it for
Coarse fibers – dense irregular CT
Gives strength and elasticity to skin
Identify layers of dermis
Identify layers of dermis
Identify arrows
Arrector pili muscle is what/ does what/ originates from where
Smooth muscle, piloerection (trap heat, response to stress), originates from dermal mesenchyme
Follicular bulge is what
Reservoir for epidermal stem cells & melanocytes, part of follicle under arrector pili
The follicular bulge can also serve what purpose
Regenerate wounded epidermis
Identify 2 landmarks
What is Ectodermal dysplasia
Group of syndromes related to mutations of the genes that code for ectodermal appendages including hair, teeth, nails, and glands.
Where does an eccrine sweat gland empty onto
Directly onto the epidermal surface
Where does an apocrine sweat gland empty onto
Directly onto hair follicle
Where does a sebaceous gland empty onto
Directly into hair follicle
Where is a sebaceous gland located
Wherever there is hairy skin
Identify arrows
A sebaceous gland is wedged between what
Arrector pili & hair follicle
A sebaceous gland is what kind of secretion
Holocrine secretion (sebum
contains lipid & cellular debris)
What are the 2 kinds of sweat glands and where are they found
Eccrine (all over), apocrine (armpit/groin)
Where does a sebaceous gland empty
Into hair follicle
What is the secretion of eccrine sweat glands
Water-rich sweat, narrow lumen, empties directly onto skin
What is the secretion of apocrine sweat glands
Protein rich sweat (active at puberty), empty into hair follicle, wide lumen
Apocrine/ eccrine sweat glands are what kind of gland
Merocrine- typical exocytosis
Identify arrows
What is a merkel disc for
Fine touch (fingertips)
What is a free nerve ending for
Pain/ temperature
What is Meissners corpuscle for
Fine touch/ fingertips
What is a pacinian corpuscle for
Sustained pressure, vibrations (deep dermis)
Free nerve ending, Merkel disk, and Pacinian corpuscle contain _______
Somatic afferent fibers
Identify
Identify
Identify
Visceral efferents (not shown) innervate eccrine glands and arrector pili mainly by ______________
Postganglionic sympathetic fibers
A thick corneum is found where
A thin corneum is found where
