SKIN Flashcards
What are the functions of skin?
- Protective: mechanical forces, pathogens, UV light, dehydration
- Sensory
- Thermoregulator
- Metabolic: Electrolytes, Vit. D
- Sexual signaling: pheromones and indicator of health
How do thick skin and thin skin differ?
- Thick skin
- Found on the palms of hand and soles of feet
- Lacks hairs, sebaceous gland, and accrine glands
- Contains sweat glands
- Melanin less abundant
- Ridges that hold epidermis to dermis are higher to resist shear.
- Has an extra layer- Stratum Lucidum
- Thin skin
- Layers are not clearly defined
List the layers of the epidermis from most deep to most superficial. What’s a defining characteristic of each?
- S. Basale – stem cells
- S. Spinosum – spiny-keratinization begins
- S. Granulosum – hydrophobic lipid envelope
- More pronounced in thick skin
- S. Lucidum – translucent appearance
- Only in thick skin
- S. Corneum – dead cells
What are the three layers of the skin? What is each layer made up of?
- Epidermis: stratified squamous epithelium
- Dermis: connective tissue
- Hypodermis: fatty, loose connective tissue
What kind of epitelium is found in the epidermis?
Keratinized Stratified squamous
The epidermis is composed mostly of _________cells that are generated in the __________ layer, and differentiate as they are pushed to the surface
keratinocyte; stratum basale
What cells are found in the S. Basale?
Stem cells
What cells are found in the S. spinosum?
Spiny-keratinization begins
What cells are found in the S. granulosum?
Hydrophobic lipid enveloped
What cells are found in the S. corneum?
Dead cells
How does a histo slide of thick skin differ from a histo slide of thin skin?
Layers of the epidermis are not clearly seen in thin skin.
Which epidermis layer is being described below?
- Highly mitotic
- Stem cells for all keratinocytes.
- Single layer of basophilic cuboidal cells attached to basement membrane.
- Contain intermediate filaments composed of keratin, bundled into tonofilaments.
- Site of synthesis of Vit D, in response to light.
S. Basale
Which epidermis layer is the site of Vit D synthesis?
S. Basale
S. Basale is also known as __________
S. Germinativum
The stratum basale is composed of a single layer of ___________ cuboidal cells attached to the basement membrane.
Basophilic
The keratin found in the stratum basale is bundled into ___________.
Tonofilaments
Keratinocytes are held together by ___________ and attached to the basement membrane by _____________.
Desmosomes; hemidesmosomes
Hemidesmosomes and desmosomes are attached to bundles of __________ fibers.
Collagen
What are the components of hemidesmosomes?
Tonofilaments
Plaque
Basal lamina
Anchoring filaments
Collagen Type I
Which molecules are involved in cell adhesion in skin?
Desmosomes
Keratin filaments
Hemidesmosomes
Anchoring filaments
Basal lamina
Type IV collagen
Anchoring fibrils (Type VII collagen)
Type I and III collagen
Anchoring plaques (Type IV collagen)
Which epidermis layer is being described below?
- Polyhedral cells attached by desmosomes.
- Shrinkage during fixation causes retraction in between desmosomes, to look like spines.
S. Spinosum
During the processing of polyhedral cells in s. spinosum layer, the cells contract and form spines, why is this?
They contract because they are held together by desmosomes
Which epidermis layer is being described below?
- Flatter keratinocytes fill with basophilic keratohyaline granules.
- The granules contain filaggrin, which links tonofibrils together to form dense bundles of keratin that fill the cell.
S. Granulosum
What type of granules are found in the stratum granulosom? What do these granules contain?
The keratinocytes in this layer are filled with basophilic kerahyalin granules that contain filaggrin.