Integuement Flashcards
What the hell is integuement?
Epidermis + dermis + hypodermis.
Name the layers of the skin, from basal layer to apical layer.
Hypodermis Dermis -reticular (deep) dermis -papillary layer Epidermis -stratum basale (germinativum) -stratum spinosum -stratum granulosum -stratum lucidum -stratum corneum
What are dermal papillae?
Finger-like projections that aid in the attachment of the epidermis to the dermis.
Which layer in the integuement can adipose tissue be found?
Hypodermis (subcutis)
What cell type (squamous, cuboidal, etc.) are found in the stratum basale (Germinativum) of the epidermis?
Single layer of cuboidal cells.
Which layer is the thickest living layer of the epidermis? What do the cells in this layer look like histologically?
Stratum spinosum. They look spiny because the during fixation the cell bodies retract but the desmosomes persist.
What is characteristic of the cells in the stratum granulosum layer of the epidermis?
2-3 layers of flattened squamous epithelial cells with coarse basophilic granules in the cytoplasm (keratin granules)
What are filaggrin and loracrin? In which cell layer are they found?
They are proteins found in stratum granulosum cells. Filaggrin assembles tonofilaments into tonofibrils, and loracrin forms a dense layer just deep to the plasma membrane which thickens and stiffens the outer surface of the cell.
What are the histologic characteristics of the stratum lucidum layer of the epidermis?
It is a very thin, translucent layer that is only seen in some preparations. Some people think it is an artifact. It isn’t easy to spot.
What are the cells in the stratum corneum packed with?
Tonofibrils.
What can be found in the papillary layer of the dermis?
Blood vessels, sensory receptors.
What does adnexa mean?
Appendages of an organ.
What is the mechanism of secretion by the eccrine sweat glands? How do they stain? Why?
Merocrine secretion. They stain dark because they pump Na+ in and out of the lumen and require numerous mitochondria to power this.
How do the sebaceous glands stain?
Not well. They look like empty bubbles due to the oily sebum.
Where are sebaceous glands located?
Usually are ~halfway up a hair follicle.
What shape are eccrine sweat glands?
Simple, coiled tubular.
What shape are sebaceous glands? What is the mechanism of secretion?
Acinar with a short duct into the hair follicle. Holocrine mechanism.
Where are apocrine sweat glands located and why are they larger than the eccrine sweat glands?
Limited distribution to the axilla, groin, eyelid and are most often associated with a hair follicle. They store their product so they are larger than the eccrine glands. They have a large lumen.
Where do hair follicles originate?
Deep in the dermis, sometimes in the hypodermis.
What are the four different regions of hair follicles?
Apical surface: Infundibulum Isthmus (between the sebaceous gland and the arrector pili muscle) Bulb Dermal papilla
What are the non-encapsulated sensory endings in the skin?
- Free nerve endings 2. Merkel cells
What is the most abundant sensory organ in the skin?
Free nerve endings.
In what layer of integuement do free nerve endings lose their Schwann cell covering?
Once they pass through the basal lamina.
What do free nerve endings sense?
Temperature, pain, pressure (note: these are the only nerve endings that can sense temp and pain)
What are Merkel cells? Where are they located?
Specialized neuroendocrine cells that are associated with free nerve endings that detect light touch and constant touch. Found in stratum basale.
Name the two types of encapsulated sensory endings.
Pacinian corpuscles and Meissner corpuscles
Where are Pacinian corpuscles found? What do they look like? What do they detect?
Found throughout the dermis and hypodermis (they are deep). They are round structures with many concnetric layers of modified Schwann cells. They detect vibrations.
Where are Miessner corpuscles found? What do they detect?
Found just under the epidermis, typically within the dermal papillae. They are very sensitive and discriminatory (used in reading Braille).
What type of CT is in the dermis?
Dense irregular
What are Langerhans cells? How do they stain?
They are antigen presenting cells in the epidermis. They don’t stain well with H & E but do stain with immunochemistry Ag stains.
What are melanocytes? Where are they located? What do they look like?
They are the cells in the stratum basale that provide pigmentation. They have dendritic extensions to help donate pigment in melanosomes to many surrounding keratinocytes.
Which AA is used to make melanosomes? What cells do this?
Melanocytes make melanosomes out of tyrosine.
What are lamellar granules? Which cells make them?
Membrane-bound (ER made) vesicles of lipid that are exocytosed from stratum granulosum cells to waterproof the skin.
What are keratohyalin granules? Are they membrane bound? Which cells make them?
Granules of fillagrin and loracrin produced by the granulosum cells. Not membrane bound.
What layer are hair follicles derived from?
Epidermis!
What cells are eccrine sweat glands and sebaceous glands derived from?
Keratinocytes
What is melanin synthesized from?
Tyrosine
Which cells in the skin are “neural-crest derived?”
Melanocytes
Name five epidermal derivatives of the skin.
Eccrine sweat glands, apocrine sweat glands, sebaceous glands, hair, nails.
What type of epithelium is found in the secretory portion of eccrine sweat glands? Ductal?
Secretory: simple columnar
Ductal: stratified cuboidal
