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Questions and Answers
Which layer of the epidermis is responsible for the synthesis of keratin and other proteins?
What type of cells are found in the Stratum basale?
What is the function of epidermal ridges in the skin?
Which layer of the skin provides the source of alive skin cells?
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What is the main function of thick skin compared to thin skin?
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Which layer of the epidermis exhibits intense mitotic activity?
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What do dermal papillae do in the skin structure?
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What is the main function of the epidermal ridges?
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In which layer of the epidermis does the synthesis of keratin predominantly occur?
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What is the main function of the dermal papillae in the skin structure?
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Which layer of the skin is responsible for the production of alive skin cells?
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What is the primary function of thick skin compared to thin skin?
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Which layer of the epidermis is characterized by intense mitotic activity?
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What role does the Stratum granulosum play in the skin structure?
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What distinguishes thick skin from thin skin in terms of layers?
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What is the main characteristic of cells in the Stratum spinosum?
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What is a distinguishing feature of the Stratum lucidum compared to other layers?
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Study Notes
Integumentary System
- The integumentary system is the largest single organ of the body.
- It consists of two main layers: the epidermis (epithelial layer of ectodermal origin) and the dermis (layer of mesodermal connective tissue).
Epidermis
- The epidermis is a stratified squamous keratinized epithelium composed of cells called keratinocytes.
- It lacks microvasculature, and its cells receive nutrients and oxygen by diffusion from the dermis.
- Epidermal cell types include:
- Keratinocytes
- Langerhan cells (antigen-presenting)
- Melanocytes (pigment-producing)
- Merkel cells (tactile epithelial cells)
Layers of the Epidermis
- Stratum basale (basal layer):
- Single layer of basophilic cuboidal or columnar cells
- Characterized by intense mitotic activity
- Contains progenitor cells for all epidermal layers
- Important feature: cytoskeletal keratins
- Source of alive skin cells
- Stratum spinosum (spinous layer):
- Thickest layer, especially in epidermal ridges
- Synthesis of keratin and other proteins takes place
- Characteristically exhibit spinous processes
- Prickle cells
- Synthesis of keratin would give the cell a spiny extension
Derivatives of the Skin
- Structures that are embedded on the skin but are otherwise considered as separate organs or tissues:
- Hair follicles and hair
- Sweat (sudoriferous) glands
- Sebaceous glands
- Nails
Functions of the Skin
- Protective:
- Provides a physical barrier against thermal and mechanical insults
- Protects against most potential pathogens and other materials
- Sensory:
- Allows us to feel tactile objects
- Thermoregulatory:
- Mechanisms for accelerating heat loss (sweat production)
- Metabolic:
- Cells of the skin synthesize vitamin D3, needed for calcium metabolism and proper bone formation
- Sexual Signaling:
- The effects of sex pheromones produced by apocrine sweat glands and other skin glands are important in attraction between sexes in all vertebrates
Subcutaneous Tissue (Hypodermis)
- Located beneath the dermis
- A loose connective tissue layer usually containing pads of adipocytes
- Adipocytes vary in number in different body regions and in size according to nutritional state
- Extensive vascular supply promotes rapid uptake of insulin or drugs injected into this tissue
Sensory Receptors
- Unencapsulated:
- Merkel cells
- Free nerve endings
- Root hair plexuses
- Encapsulated:
- Meissner corpuscles
- Lamellated (pacinian) corpuscles
- Krause end bulbs
- Ruffini corpuscles
Dermis
- The surface of the dermis is very irregular and has many projections (dermal papillae) that interdigitate with projections (epidermal pegs or ridges) of the epidermis.
- Especially in skin subject to frequent pressure, where they reinforce the dermal-epidermal junction.
- Epidermal ridges are extensions of the epidermis to the dermis.
- Dermal papillae connect the dermis to the epidermis.
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Description
Test your knowledge on the integumentary system with this quiz based on Junqueira’s Basic Histology 13th Edition. Explore topics such as the layers of the skin, epidermis, dermis, and derivatives of the skin.
