CS&B - Histology - Skin Flashcards
From superficial to deep, what are the layers of epidermis?
(What mnemonic might be helpful in remembering these?)
Stratum corneum,
stratum lucidum (in thick skin only),
stratum granulosum,
stratum spinosum,
stratum basale
(Come, let’s get sunburned!)
What separates the epidermis from the dermis?
The basement membrane (basal lamina + reticular lamina)
From superficial to deep, what are the two layers of the dermis?
The papillary layer;
the reticular layer
Of what type of tissue is the dermal papillary layer composed?
Loose connective tissue (areolar)
Of what type of tissue is the dermal reticular layer composed?
Dense irregular connective tissue
Of what type of tissue is the dermal papillary layer (superficial) composed?
Of what type of tissue is the dermal reticular layer (deep) composed?
Loose connective tissue (areolar);
dense irregular connective tissue
The inferiorly oriented projections of the epidermis are called:
The superiorly oriented projections of the dermis are called:
Epidermal ridges;
dermal papillae
Name all the layers of thick skin from superficial to deep.
Stratum corneum (epidermis)
Stratum lucidum (epidermis)
Stratum granulosum (epidermis)
Stratum spinosum (epidermis)
Stratum basale (epidermis)
Basal lamina (basement membrane)
Reticular lamina (basement membrane)
Dermal papillary layer (dermis)
Dermal reticular layer (dermis)
What epidermal layer is found in thick skin but not thin skin?
The stratum lucidum
Hair follicles, sudoriferous glands, sebaceous glands, nails, and mammary glands are all derived from what layer of skin?
The epidermis
(although many project into the dermis)
What are some important functions of the integument?
Protection
Sensory
Thermoregulatory
Water maintenance
Endocrine
Identify the epidermis in this slide.
Identify the dermis in this slide.
Identify the subcutaneous tissue in this slide.
Identify the first deep layer in this slide that is not part of the integument.
Is the epidermal layer a part of the integument?
Is the dermal layer a part of the integument?
Is the subcutaneous layer a part of the integument?
Is the panniculus carnasus layer a part of the integument?
Yes
Yes
No
No
Which general portion of the skin is the thickest?
Which general portion of the skin is vascular and innervated?
The dermis;
the dermis
What is the primary cell of the epidermis?
The keratinocyte
Identify the structures indicated by the letters in this slide.
Stratum corneum;
stratum granulosum;
stratum spinosum;
epidermal projection;
dermal papilla;
stratum basale;
dermis
Which epidermal layer appears on histology as a dark line separating the keratinized cells from the normal, nucleated keratinocytes?
The stratum granulosum
Which epidermal layer is the primary creation point of the waterproofing layer of the skin?
The stratum granulosum
(the waterproofing layer then extending up into the stratum corneum)
What two cell junctions are especially important in the basal layer of the epidermis?
Desmosomes and hemidesmosomes
Name a few histologic appearances of the stratum basale.
Closely spaced nuclei
Basophilic
Melanin
(Note: B in image)
Describe the appearance of the stratum spinosum.
What cell junction is present in both the stratum spinosum and basale?
Larger and flatter cells than in the stratum basale;
desmosomes
(Note: the ‘spines’ on the cells are an artifact of slide preparation)
Is the stratum spinosum keratinized?
Is the stratum granulosum keratinized?
Is the stratum lucidum/corneum keratinized?
No;
no;
yes
Which layer of the epidermis is just superficial to the stratum basale?
The stratum spinosum
Which layer of the epidermis is just deep to the stratum lucidum?
The stratum granulosum
Which layer of the epidermis is just deep to the stratum spinosum?
The stratum basale
Why is the stratum granulosum named what it is?
It is a site of plentiful keratohyalin granules
Release of what substance in what layer of the epidermis results in cornification?
Filaggrin;
stratum granulosum
What is strange and very poorly understood about the apoptosis that occurs in the stratum granulosum?
It has typical apoptotic changes with no cellular fragmentation
Describe the intracellular makeup of the stratum corneum.
Mostly filled with keratin;
no nucleus or cytoplasmic organelles
Where is thick skin found in the body?
The volar surfaces (soles of the hands and feet)
The subcutaneous tissue loosely binds what structures together?
Why?
The skin and adjacent organs;
to allow movement
What are two reasons a person might have naturally darker skin?
The person produces more melanin and/or degrades melanin at a slower rate
(melanocyte:keratinocyte ratios are constant from person to person and from skin color to skin color)
How does the ratio of keratinocytes to melanocytes change from person to person?
It doesn’t
(relatively constant among individuals)
What cell junctions are relevant in melanocytes when compared with basal cells?
Hemidesmosomes
(NOT desmosomes)
What cell of the skin is of neural crest origin?
Melanocytes
Starting with tyrosine, how is melanin made?
Tyrosine – (tyrosinase) –> DOPA —-> melanin
What enzyme converts tyrosine to DOPA? This then becomes what?
Tyrosinase;
melanin
The tyrosine-to-DOPA reaction occurs in what organelle?
The promelanosome
What are melanosomes?
Precursors to melanin granules
How do keratinocytes get melanin from melanocytes?
They envelop melanocyte projections
(cytocrine secretion by melanocytes)
What is the purpose of melanin?
To protect nucleic acid from UV rays
How do melanocytes appear on histology?
As very translucent cells with dark centers
What are the APCs of the skin?
Langerhans cells
The dermis comes from what embryonic derivative?
The dermatomyotome
(a portion of the somite, which is derived from para-axial mesoderm)
What is the dermis like in regards to innervation, vascularization, and lymphatic supply?
Highly supplied in all 3
Where can postganglionic sympathetic fibers be easily found clustering in the skin?
Surrounding hair follicles
(Note: I would assume, some can be found around arteries and sweat glands as well)
Describe the papillary layer of the dermis.
Loose connective tissue:
collagen types I and III, some elastic fibers
Hemidesmosomes anchor what cytoskeletal component to the basal lamina?
Intermediate filaments
What two fiber types are most prevalent in the reticular layer of the dermis?
Type I collagen;
elastic fibers
What are the purpose of the collagen fibers in the reticular layer of the dermis?
What are the purpose of the elastic fibers in the reticular layer of the dermis?
What are the purpose of the reticular fibers in the reticular layer of the dermis?
Strength;
flexibility and recoil;
there are very few (reticular layer = misnomer)
Where are apocrine sweat glands found in the body?
The axillary and perineal regions
(also, the eyelids)
Is the stratum lucidum often very thick when compared to the stratum corneum?
No;
it is a thin, grayish-white layer superficial to the stratum granulosum
What type of secretion do both eccrine and apocrine sweat glands use?
Merocrine secretion
(confusingly, apocrine sweat glands do NOT use apocrine secretion)
What type of sweat glands use merocrine secretion?
What type of sweat glands use apocrine secretion?
What type of sweat glands use holocrine secretion?
Eccrine, apocrine;
none;
none
(Note: apocrine sweat glands due not use apocrine secretion)