Questions and Answers
What does the integumentary system consist of?
Skin and accessory tissues (examples: nails, hair, sweat glands, sebaceous glands).
What is the scientific study of the integument called?
Dermatology
What percentage of body weight does the skin account for?
7-8%
What are the layers of the integument?
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What type of epithelium is the epidermis made of?
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What types of cells are found in the stratum basale?
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What begins to develop in the stratum spinosum?
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What do epithelial dendritic cells do?
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What do keratinocytes produce?
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What pigment do melanocytes produce?
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What are tactile cells also known as?
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What is the stratum granulosum composed of?
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Where is the stratum lucidum found?
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What are the characteristics of the stratum corneum?
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Study Notes
Integumentary System Overview
- Comprises skin and accessory tissues such as nails, hair, sweat glands, and sebaceous glands.
- Skin, also known as the cutaneous membrane, includes all four tissue types.
- Represents the body's largest organ, accounting for 7-8% of body weight.
Functions and Importance of the Integument
- Acts as a barrier protecting internal structures from external threats.
- Serves as a visual indicator of physiological health.
- Thickness varies by location; thicker on palms and soles due to an increased stratum corneum.
Layers of the Integument
- Epidermis: Composed of stratified squamous epithelium.
- Dermis: Lies deep to epidermis, made primarily of dense irregular connective tissue.
- Subcutaneous Layer (Hypodermis): Beneath dermis, made of alveolar and connective tissue; not part of the integumentary system.
Epidermis Structure
- Formed by keratinized, stratified squamous epithelium; contains five layers from deep to superficial:
- Stratum Basale: The deepest layer, consisting of living keratinocytes; also contains melanocytes and tactile cells.
- Stratum Spinosum: Several layers of keratinocytes that look spiny; contains epidermal dendritic cells involved in immune response.
- Stratum Granulosum: 3-5 layers of keratinocytes; marks the first stage of keratinization.
- Stratum Lucidum: Present only in thick skin (palms and soles); filled with eleidin, a translucent protein.
- Stratum Corneum: 20-30 layers of dead, keratinized cells; forms a tough protective outer layer.
Specific Cell Types in the Epidermis
- Keratinocytes: Most abundant cells; responsible for synthesizing keratin to strengthen and protect the epidermis.
- Melanocytes: Produce and store melanin; protect against UV radiation by transferring pigment to keratinocytes.
- Tactile Cells (Merkel Cells): Sensitive to touch; release chemicals upon compression to stimulate sensory nerve endings.
Summary of Keratinization
- Involves the process where keratinocytes fill with keratin, leading to cell death; crucial for skin barrier function.
- The process completes as cells move to more superficial layers, eventually forming the protective stratum corneum.
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Description
Explore the fascinating world of the integumentary system, which includes the skin and its various accessory structures like nails and hair. Understand its essential functions in protecting the body and serving as a key indicator of overall health. Dive into the layers of the skin, their structures, and how they contribute to the body's largest organ.
