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Questions and Answers
Which layer of the skin is avascular?
Which layer of the skin is avascular?
Melanocytes produce keratin, which helps waterproof the skin.
Melanocytes produce keratin, which helps waterproof the skin.
False
What is the primary function of the integumentary system?
What is the primary function of the integumentary system?
To regulate body temperature and protect the body from external insults
The layer of skin that anchors all structures to the fascia is the ______ layer.
The layer of skin that anchors all structures to the fascia is the ______ layer.
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Match the following skin cell types with their functions:
Match the following skin cell types with their functions:
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What is the primary function of hair?
What is the primary function of hair?
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The medulla is the most superficial layer of hair.
The medulla is the most superficial layer of hair.
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What are the two types of skin cancers mentioned?
What are the two types of skin cancers mentioned?
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Hair protects the scalp from _____ invasion.
Hair protects the scalp from _____ invasion.
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Match the following skin cancer types with their characteristics:
Match the following skin cancer types with their characteristics:
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Which layer of hair makes up the bulk of the hair?
Which layer of hair makes up the bulk of the hair?
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The arrector pili muscles are associated with hair follicles.
The arrector pili muscles are associated with hair follicles.
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The outer layer of the hair follicle is made of _______ tissue.
The outer layer of the hair follicle is made of _______ tissue.
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What is the primary function of tactile epithelial cells?
What is the primary function of tactile epithelial cells?
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The epidermis consists of only three strata.
The epidermis consists of only three strata.
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What type of cells are found in the stratum basale that are capable of dividing?
What type of cells are found in the stratum basale that are capable of dividing?
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The stratum _______ is responsible for sealing the epidermis and contains dying cells.
The stratum _______ is responsible for sealing the epidermis and contains dying cells.
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Match the following strata of skin to their characteristics:
Match the following strata of skin to their characteristics:
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How long does it take for new cells at the stratum basale to reach the stratum corneum?
How long does it take for new cells at the stratum basale to reach the stratum corneum?
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Keratinization refers to the process of cells accumulating keratin as they die.
Keratinization refers to the process of cells accumulating keratin as they die.
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What are the two regions of the dermis?
What are the two regions of the dermis?
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Fingerprints are formed by the shape of the _______ papillae.
Fingerprints are formed by the shape of the _______ papillae.
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What primarily causes differences in human skin color?
What primarily causes differences in human skin color?
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Melanocytes have an enzyme called tyrosinase that assists in melanin synthesis.
Melanocytes have an enzyme called tyrosinase that assists in melanin synthesis.
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What happens to skin when a tan fades?
What happens to skin when a tan fades?
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Tattoos are deposited in the _______ of the skin.
Tattoos are deposited in the _______ of the skin.
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Which layer of the epidermis is characterized by dying cells undergoing apoptosis?
Which layer of the epidermis is characterized by dying cells undergoing apoptosis?
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Study Notes
The Integumentary System
- Includes skin, hair, nails, oil and sweat glands, and sensory receptors
- Skin is the largest organ, accounting for 7% of body weight
- Skin thickness varies from 0.5mm on eyelids to 4mm on heels
- Epidermis, the outer layer of skin, is avascular
- Dermis, the middle layer of skin, is vascularized and made of connective tissue
- Subcutaneous layer, or hypodermis, anchors skin structures to fascia and contains pressure receptors
Key Functions of the Integumentary System
- Regulates body temperature
- Protects the body from external insults
- Senses signals
- Excretes and absorbs chemicals
- Stores blood and energy
- Synthesizes vitamin D
The Epidermis
- Composed of keratinized stratified squamous epithelium
- Contains various cell types, including:
- Keratinocytes: Layered cells that produce keratin and waterproof sealant
- Melanocytes: Contain melanin granules, which are brown-black pigments that absorb UV light and protect DNA
- Intraepidermal macrophages (Langerhans cells): UV-sensitive phagocytes that engulf and destroy invaders via phagocytosis
- Tactile epithelial cells: Sense touch and are in direct contact with tactile discs
Epidermal Strata
- The epidermis can be further divided into strata, which are layers of keratinocytes of different maturity
- Most of the body has four strata
- Palms and soles have five strata
- From deepest to most superficial, the strata are:
- Stratum basale: Contains stem cells that replenish other strata, rich in keratin intermediate filaments
- Stratum spinosum: Provides strength to skin, composed of 8-10 layers of flat keratinocytes
- Stratum granulosum: Seals the epidermis and contains dying cells, produces lamellar granules and keratohyalin
- Stratum corneum: Most superficial layer, composed of dead, flat cells that sloughed off
- Stratum lucidum: Only found in thick skin, made of dead, flat keratinocytes and provides additional mechanical support
Epidermal Growth
- Takes 4-6 weeks for new cells at the stratum basale to emerge at the stratum corneum
- Keratinization reinforces skin by accumulating keratin in cells that die by apoptosis
- Cells further from the stratum basale have decreased access to nutrients
The Dermis
- Made of connective tissue, providing great tensile strength
- Two regions:
- Papillary region: Made of areolar connective tissue with collagen and elastic fibers, contains dermal papillae, nervous tissue, and capillaries
- Reticular region: Composed of dense irregular connective tissue, consists of a mesh-like network of thick collagen fibers, interspersed with fibroblasts and other cells
Fingerprints
- Formed by epidermal ridges that dig in
- Unique to each individual, even between identical twins
- Shape of the dermal papillae determines fingerprint pattern
- Increase friction, aiding grip and surface area for touch sensation
Structural Basis for Human Skin Color
- Differences in human skin color are due to the amount of melanin secreted by melanocytes
- Accumulation of melanin can appear as freckles, age spots, or nevuses (moles)
- Tanning is caused by increased tyrosinase activity upon UV light exposure
- A tan fades because skin dies and gets replaced by cells that produce less melanin
Tattoos
- Ink is deposited into the dermis, making them permanent
- Laser treatment destroys pigmented cells, leading to phagocytosis of cell debris
Accessory Structures of the Skin: Hair, Glands, and Nails
- Hair protects and insulates the body, and helps sensing stimuli
- Hair can be found on the scalp, eyebrows, eyelashes, nasal cavity, axillae, and external genitalia
Hair Anatomy
- Hair consists of:
- Root: Embedded in the dermis or subcutaneous layer
- Shaft: Superficial portion of the hair
- Both the root and shaft consist of three layers:
- Medulla: Deepest layer, contains pigmented cells
- Cortex: Middle layer, makes up the bulk of hair
- Cuticle: Most superficial layer, made of flat keratinized epithelial cells
- The hair follicle surrounds the hair root:
- External layer is made of epithelial tissue
- Internal layer comprises the hair matrix, which divides continuously for hair growth
Hair and Associated Structures
- Hair interacts with arrector pili, a smooth muscle, that contracts under cold or fear
- Hair follicle is associated with receptors that sense movement
Skin Cancer
- Basal cell carcinomas: Involve cells in the stratum basale, most common type, generally benign
- Squamous cell carcinomas: Involve cells in the stratum spinosum, represent 20% of skin cancers
- Malignant melanomas: Cancers of melanocytes
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Description
Explore the fascinating details of the integumentary system, which includes the skin, hair, nails, and glands. This quiz will cover the key functions, structure, and layers of the skin, along with their roles in protecting the body. Test your knowledge about this vital organ system and its importance to overall health.
