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Questions and Answers
Which of the following is NOT a function of the integumentary system?
What type of tissue primarily composes the dermis layer of the skin?
Which layer of the epidermis contains stem cells that undergo cell division?
Which type of cell in the epidermis is primarily responsible for the production of melanin?
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What is the primary function of keratin produced by keratinocytes in the epidermis?
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Which skin layer is primarily responsible for the presence of keratohyalin granules?
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What function does the stratum spinosum primarily serve in the epidermis?
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Which of the following statements about the stratum corneum is most accurate?
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The redness of the skin is primarily attributed to which pigment?
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What is a characteristic feature of the stratum lucidum, and where is it found?
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Which layer of the epidermis is characterized by the presence of lipid-rich lamellar granules?
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What primarily contributes to the toughness of the skin in the stratum lucidum?
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Which component of the dermis primarily allows it to resist stretching?
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How does skin color primarily vary among individuals despite a similar number of melanocytes?
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What condition is characterized by an excessive shedding of keratinized cells from the scalp?
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Study Notes
Integumentary System Overview
- Comprises skin (cutaneous membrane) and accessory structures (hair, glands, nails, sensory receptors).
- Largest system in the human body.
Functions
- Protects the body from external harm.
- Regulates body temperature (thermoregulation).
- Synthesizes Vitamin D.
- Provides sensory information.
- Maintains homeostasis.
Skin Structure
- Two major layers:
- Epidermis: Outer layer, composed of epithelial tissue, avascular.
- Dermis: Inner layer, made of connective tissue.
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Hypodermis (subcutaneous tissue):
- Stabilizes skin, consists of elastic and adipose tissues, contains few capillaries.
- Site for subcutaneous injections.
Epidermis Layer Details
- Contains four types of cells:
- Keratinocytes: Produce keratin to protect and prevent dehydration.
- Melanocytes: Produce melanin, influencing skin color.
- Langerhans cells: Involved in immune responses.
- Merkel cells: Responsible for touch sensation.
- Composed of 4-5 layers:
- Stratum Corneum: Outermost layer of dead keratinocytes.
- Stratum Lucidum: Present only in thick skin (e.g., palms, soles).
- Stratum Granulosum: Keratinocytes undergoing apoptosis and granule formation.
- Stratum Spinosum: Provides strength and flexibility; contains Langerhans and melanocytes.
- Stratum Basal: Includes stem cells and melanocytes.
Keratinization and Skin Growth
- Cells in the stratum basal push toward the surface, accumulate keratin, and undergo apoptosis.
- Excessive shedding of keratinized cells from the scalp is known as dandruff.
Dermis Structure
- Composed of blood vessels, nerves, glands, and hair follicles.
- Divided into:
- Papillary Layer: Superficial, rich in nerve endings.
- Reticular Layer: Thick, rich in collagen fibers, resists stretching.
Skin Color
- Determined by melanin, hemoglobin, and carotene.
- Melanocyte counts are similar in all individuals; variations in skin color arise from pigment amounts.
- UV exposure increases melanin production.
Accessory Structures
- Hair: Composed of dead, keratinized cells; provides protection and insulation.
-
Hair Structure:
- Shaft (above skin) and follicle (below skin), associated with arrector pili muscle.
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Glands:
- Sebaceous Glands: Produce sebum; protect from drying and inhibit bacteria.
- Eccrine Sweat Glands: Most numerous, open at the epidermis.
- Apocrine Sweat Glands: Located in hairy skin, activated at puberty.
- Ceruminous Glands: Modified sweat glands in the ear canal.
Nails
- Composed of hard, keratinized cells; includes free edge, nail body, and root.
Sensory Receptors
- Superficial: Merkel and Meissner receptors (respond to light touch).
- Deep: Pacinian corpuscle and Ruffini receptors (respond to pressure and vibration).
Thin vs. Thick Skin
- Thin Skin: Covers most body areas, lacks stratum lucidum, contains hair and sebaceous glands.
- Thick Skin: Found in palms and soles, has stratum lucidum, fewer hairs, more sweat glands.
Wound Healing
- Two types:
- Epidermal Healing: Affects only the epidermis.
- Deep Healing: Involves dermis and subcutaneous layers.
Development
- Epidermis arises from ectoderm; dermis originates from mesoderm.
Aging Effects
- Wrinkles, dehydration, reduced sweat production, gray hair, and thinner skin occur with age.
- Increased risk of pressure ulcers (bed sores).
Skin Cancer
- Caused by excessive UV exposure; three major types:
- Basal Cell Carcinoma
- Squamous Cell Carcinoma
- Malignant Melanoma
Burns Classification
- First-Degree: Affects only the epidermis (e.g., sunburn).
- Second-Degree: Destroys epidermis and part of dermis (blister).
- Third-Degree: Full-thickness burn affecting all skin layers.
- Rule of Nines: Used to estimate the total body surface area affected by burns.
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Description
Explore the major components and functions of the integumentary system, which includes the skin and its accessory structures. Learn how this vital system protects the body, regulates temperature, synthesizes vitamin D, and provides sensory information.
