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Questions and Answers
Which of the following statements about sebaceous glands is true?
Which of the following statements about sebaceous glands is true?
Which component is NOT found in eccrine sweat?
Which component is NOT found in eccrine sweat?
What type of burn affects only the epidermis?
What type of burn affects only the epidermis?
Which type of glands secrete earwax?
Which type of glands secrete earwax?
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In the context of burns, which type is characterized by no pain?
In the context of burns, which type is characterized by no pain?
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Which of the following correctly describes the rule of nines?
Which of the following correctly describes the rule of nines?
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What kind of secretion involves the entire secreting cell forming part of the secretion?
What kind of secretion involves the entire secreting cell forming part of the secretion?
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What is the primary role of sweat glands?
What is the primary role of sweat glands?
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Which of the following describes the characteristic appearance of a second degree burn?
Which of the following describes the characteristic appearance of a second degree burn?
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Which type of sweat gland is primarily responsible for body odor?
Which type of sweat gland is primarily responsible for body odor?
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Which layer of the epidermis is primarily responsible for the synthesis and release of melanin?
Which layer of the epidermis is primarily responsible for the synthesis and release of melanin?
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What is the primary function of Langerhans cells located within the stratum spinosum?
What is the primary function of Langerhans cells located within the stratum spinosum?
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Which structure in the dermis is primarily responsible for temperature regulation?
Which structure in the dermis is primarily responsible for temperature regulation?
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In thick skin, which layer of the epidermis is directly responsible for providing a barrier against loss of water?
In thick skin, which layer of the epidermis is directly responsible for providing a barrier against loss of water?
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Which layer of the dermis is characterized by loose areolar connective tissue and forms fingerprints?
Which layer of the dermis is characterized by loose areolar connective tissue and forms fingerprints?
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What is the predominant tissue type found in the reticular layer of the dermis?
What is the predominant tissue type found in the reticular layer of the dermis?
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Which cell type is specifically associated with sensory reception in the epidermis?
Which cell type is specifically associated with sensory reception in the epidermis?
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What is the main function of keratinocytes as they move from the stratum basale to the stratum corneum?
What is the main function of keratinocytes as they move from the stratum basale to the stratum corneum?
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Which statement correctly describes the hypodermis?
Which statement correctly describes the hypodermis?
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What is the role of the arrector pili muscle in relation to hair follicles?
What is the role of the arrector pili muscle in relation to hair follicles?
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Study Notes
Integumentary System
- The integumentary system is composed of skin and its appendages.
- Skin is the largest organ in the body.
- Dermatology is the medical specialty concerning diagnosing and treating skin disorders.
Functions of Skin
- Protection: Cushions, insulates, waterproofs, protects from chemicals, heat, cold, and bacteria, screens UV rays.
- Synthesizes vitamin D: with UV rays
- Regulates body temperature: Vasodilation (increases blood flow) and vasoconstriction (decreases blood flow) regulate body temperature. Sweating is a key mechanism.
- Prevents unnecessary water loss
- Sensory reception: Nerve endings detect stimuli (temperature, pain, pressure, touch).
- Excretion: Sweat removes water, salts, uric acid, and ammonia.
- Blood reservoir: Dermis contains blood vessels carrying 8-10% of total blood flow in a resting adult.
Types of Skin
- Most of the body is made up of thin skin.
- Thick skin is non-hairy, found on the palm and sole of the foot.
- Thickness of the skin is due to the thickness of the epidermis.
- Layers of skin: Epidermis, Dermis, subcutaneous layer
Epidermis
- Composed of stratified squamous keratinized epithelium.
- Contains keratinocytes, melanocytes (produce melanin), Merkel cells, and Langerhans cells.
- Layers (deep to superficial): Stratum basale (germinativum), stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum.
- Keratinocytes are the predominant cell type.
- Melanocytes produce melanin for skin pigmentation and UV protection.
- Merkel cells are associated with sensory nerve endings.
- Langerhans cells are immune cells.
Stratum Basale (Germinativum)
- Deepest layer of the epidermis.
- Single layer of columnar or cuboidal keratinocytes.
- Melanocytes and Merkel cells reside here.
- Keratinocytes divide and push other cells upwards.
Stratum Spinosum
- 8-10 layers of polyhedral cells (with many sides).
- Cells are connected by desmosomes.
- Contains Langerhans cells.
Stratum Granulosum
- Cells become flat (3-5 layers).
- Keratohyaline granules accumulate.
- Nuclei and other cellular components disintegrate.
- Cells begin to die.
Stratum Lucidum
- Only present in thick skin.
- Several layers of clear, flat dead cells.
- Faint nuclear outlines may be visible.
- Keratinocytes are filled with the protein eleidin.
Stratum Corneum
- Most superficial layer.
- Many layers of flattened, dead, keratinized cells.
- Cells are filled with keratin.
- Nuclei are not visible.
- Cells are constantly shed.
- Lipids cement the cells together into a membrane.
Dermis
- Strong, flexible connective tissue layer.
- Cells include fibroblasts, macrophages, mast cells, and WBCs.
- Fiber types: collagen, elastic, reticular.
- Rich supply of nerves and vessels.
- Critical role in temperature regulation.
- Two layers: papillary and reticular.
- Thick skin contains sweat glands.
- Thin skin contains sweat glands, sebaceous glands, hair follicles, and arrector pili muscles.
Papillary Layer
- Loose areolar connective tissue.
- Forms dermal papillae - fingerprints.
- Highly vascular
Reticular Layer
- Dense irregular connective tissue.
- Sebaceous (oil) glands
- Arrector pili muscles
- Hair follicles
- Sudoriferous (sweat) glands
- Meissner's corpuscles (fine touch, discriminative touch, vibration)
- Pacinian corpuscles (vibration and pressure)
Hypodermis
- "Hypodermis" (Gk) or "Subcutaneous" (Latin)
- Below the skin
- Also called "superficial fascia"
- Fatty tissue stores fat and anchors skin (areolar tissue and adipose cells)
Skin Appendages
- Derived from epidermis but extend into dermis;
- Hair and hair follicles
- Sebaceous (oil) glands
- Sweat (sudoiferous) glands
- Nails
Nails
- Made of hard, flexible plates of keratin.
- Proximal part is called nail root and covered by fold of skin.
- Keratinized nail plate is bound to nail bed.
- Nail plate grows from nail matrix.
- Cells of nail matrix divide, move distally become keratinized, and form the nail root.
Hair
- Absent in the region of palm, sole, lips, nipples, external genitalia (glans penis, clitoris, and labia minora).
- Composed of dead, keratinized cells.
- Parts: shaft (superficial portion) and root (below surface in dermis)
- Shaft and root are composed of three layers: medulla, cortex, and cuticle.
Hair Follicle
- Epidermal tube in which hair root is situated.
- Extends into dermis.
- Dilated at its base to form hair bulb.
- Dermal papilla containing blood capillaries is located in hair bulb.
- Arrector pili muscles extend from hair follicle to papillary layer of dermis; these muscles are supplied by sympathetic nerves, and cause hair to stand on end ("goosebumps") when contracted.
Sebaceous Glands
- Found in the dermis of thin skin
- Opens into upper portion of hair follicle.
- Produce sebum (oil).
- Sebum lubricates and waterproofs the skin and hair.
Sweat Glands
- Found in entire skin surface except nipples and external genitalia.
- Prevent overheating.
- Sweat produced in response to stress and heat.
- Acinus lined by columnar cells.
Types of Sweat Glands
- Eccrine (merocrine) - most numerous, true sweat, 99% water.
- Apocrine - axillary, genital areas, ducts open in hair follicles, odor develops as organic molecules decompose; sometimes considered a modified apocrine gland.
- Ceruminous - secrete earwax
- Mammary - secrete milk
Burns
- Injury to skin or other organic tissue from heat, radiation, radioactivity, electricity, friction, or chemicals.
- Types: thermal, radiation, chemical, electrical
Classification of Burns
- First-degree burns (superficial): Affect only the epidermis. Dry with blanchable redness.
- Second-degree burns (partial thickness): Affect epidermis and upper dermis. Painful blisters. Red, moist, shiny.
- Third-degree burns (full thickness): Destroys all layers of skin. Damages nerve endings. Characterized by dry, waxy white, leathery, or charred black color; non-blanchable.
- Fourth-degree burns (full thickness): Deepest and most severe. Destroys all skin layers and possibly bone, muscle, and tendons. No pain.
Rule of Nines
- Used to estimate the percentage of total body surface area (TBSA) burned.
- Divides the body into percentages.
- Used in the initial management of burn patients and fluid resuscitation.
- Usually used for 2nd, 3rd, and 4th-degree burns.
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Description
Explore the integumentary system, which includes the skin and its appendages, and discover the key functions of skin such as protection, temperature regulation, and sensory reception. Learn about the different types of skin and their roles in overall body health.
