Integument Flashcards
1
Q
Stratum Spinosum
A
- second epidermal layer, several cell layers thick
- contains polyhedral keratinocytes with spiny processes
- layer thicken with pressure to produce corns & calluses
2
Q
Stratum Granulosum
A
- third epidermal layer, thickest layer of non-keratinized cells
- layer where keratin begins to be produced, cells start to flatten out in shape (irregularly shaped, variable in size)
- basophilic, cysteine & histidine rich proteins
- are precursors to filagrin, which assemble keratin into bundles
3
Q
Stratum Corneum
A
- fourth epidermal layer, annucleate (no nucleus and organelles)
- filled almost entirely with mature keratin
- plasma membrane coated with lipids, forming water barrier of epidermis
- continuously shed, (thick skin = 15-40 layers, thin skin = 10-20 layers)
4
Q
Stratum Lucidium
A
- subdivision of stratum corneum
- only seen well in thick skin
- typically poorly stained, translucent band of cells (lucid = clear)
- derived from Corneum, no organelles or nuclei
5
Q
What is the predominant cell type of the epidermis?
A
Keratinocytes
- they produce keratin, make up 85% of cells
- they participate in the epidermal water barrier
- will produce cornified cells, full of keratin, undergo keratinization and desquamation
6
Q
Melanocytes
A
- neural crest derived, scattered along stratum basale
- produce melanin and transfer it to keratinocytes
7
Q
What is an epidermal-melanin unit?
A
one melanocyte maintains an association with a specific number of keratinocytes (1:36)
8
Q
Langerhans Cells
A
- antigen-presenting cells (APCs) that provide defense against pathogens
- identifiable in stratum spinosum, have pale cytoplasm with long processes
- they develop from monocyte precursors
- antigens are phagocytized and displayed on the cell surface, cell migrates to a nearby lymph node to activate T-lymphocyte
9
Q
Merkel Cells
A
- epidermal cells that function in cutaneous sensation
- provide acute sensory perception in the fingertips (are associated with nerve endings)
- reside in stratum basale
10
Q
Layers of the Dermis
A
- Papillary layer: loose CT immediately beneth epidermis, includes dermal papilla and ridges, contains vasculature and nerve endings
- Reticular layer: deep to papillary, thicker and less cellular, thick irregular bundles of Type I collagen and coarse elastic fibers, form Langer’s Lines (regular lines of tension, where surgical incisions should follow to allow for optimal healing)
11
Q
Hypodermis
A
- subcutaneous fascia
- adipose tissue, varies in thickness/body region
- energy storage site, insulation
- Arrector pili muscles -> hair follicles
12
Q
Meissner’s Corpuscle
A
- touch receptors responsive to low-frequency stimuli (like reading brail)
- tapered cylinders oriented perpendicular to the skin surface
- present in dermal papilae just beneath the epidermis
13
Q
Pacinian Corpuscle
A
- looks like an onion, large ovoid structures found in the deeper dermis and hypodermis (numberour layers & thickness)
- found in fingertips, joints, periosteum and internal organs
- detect pressure or vibration
- myelinated nerve ending surrounded by a capsule sturucture
14
Q
Free Nerve Endings
A
- terminate in the stratum granulosm
- “free” in that they lack connective tissue
- detect fine touch (not vibration), heat, cold and pain
- free dermal endings surround most hair follicles (sensitive to hair movement and mechanoreceptors)
15
Q
Sebaceous Glands
A
- several glands per follicle
- adundant on face & scalp
- produce a lipid mixture, sebrum via holocrine secretion
- waxy mix of tryglycerides and cholesterol (lubricates, softens and waterproofs skin)
- sebum discharged into infundibulum (hair follicle), forming pilosebaceous canal
