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Questions and Answers
What is the function of the cuticle in hair structure?
What is the function of the cuticle in hair structure?
Which layer of the hair follicle surrounds the hair root?
Which layer of the hair follicle surrounds the hair root?
What is the role of the arrector pili muscle?
What is the role of the arrector pili muscle?
Which statement correctly describes the cortex of the hair?
Which statement correctly describes the cortex of the hair?
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What characterizes the glassy membrane in the hair follicle?
What characterizes the glassy membrane in the hair follicle?
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What type of keratin is found in the medulla of hair?
What type of keratin is found in the medulla of hair?
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Which structure wraps around the base of the hair follicle?
Which structure wraps around the base of the hair follicle?
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What type of muscle makes up the arrector pili muscle?
What type of muscle makes up the arrector pili muscle?
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Which of the following statements about the external root sheath is correct?
Which of the following statements about the external root sheath is correct?
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Where in the human body is hair NOT present?
Where in the human body is hair NOT present?
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What is the role of sebaceous glands associated with hair?
What is the role of sebaceous glands associated with hair?
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What characterizes terminal hairs?
What characterizes terminal hairs?
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What type of scar is characterized by being raised and occurs within the boundaries of the original injury?
What type of scar is characterized by being raised and occurs within the boundaries of the original injury?
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What structure is responsible for hair production?
What structure is responsible for hair production?
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In first degree burns, which layer of the skin is affected?
In first degree burns, which layer of the skin is affected?
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What is a potential danger associated with burns that occur on the face?
What is a potential danger associated with burns that occur on the face?
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Which of the following is NOT a characteristic effect of aging on the skin?
Which of the following is NOT a characteristic effect of aging on the skin?
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What is the purpose of the Rule of Nines in relation to burns?
What is the purpose of the Rule of Nines in relation to burns?
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What type of tissue primarily makes up the papillary layer of the dermis?
What type of tissue primarily makes up the papillary layer of the dermis?
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Which factor is NOT associated with decreased skin turgor?
Which factor is NOT associated with decreased skin turgor?
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What characterizes dermatitis?
What characterizes dermatitis?
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Which receptors in the dermis are responsible for light touch sensations?
Which receptors in the dermis are responsible for light touch sensations?
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Which statement is true regarding the lines of cleavage in the dermis?
Which statement is true regarding the lines of cleavage in the dermis?
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What is the primary function of the hypodermis?
What is the primary function of the hypodermis?
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Which layer of the dermis contains larger blood vessels and lymphatics?
Which layer of the dermis contains larger blood vessels and lymphatics?
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What type of connective tissue is primarily found in the reticular layer of the dermis?
What type of connective tissue is primarily found in the reticular layer of the dermis?
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What primarily causes a bruise (contusion)?
What primarily causes a bruise (contusion)?
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Which of the following statements about the dermal blood supply is true?
Which of the following statements about the dermal blood supply is true?
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What is the primary role of melanocytes in hair color?
What is the primary role of melanocytes in hair color?
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Which of the following correctly describes the properties of sebum?
Which of the following correctly describes the properties of sebum?
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What distinguishes apocrine sweat glands from merocrine sweat glands?
What distinguishes apocrine sweat glands from merocrine sweat glands?
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Which of these options is NOT a function of hair?
Which of these options is NOT a function of hair?
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What condition is characterized by inflammation around a hyperactive sebaceous gland?
What condition is characterized by inflammation around a hyperactive sebaceous gland?
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How do merocrine sweat glands primarily cool the body?
How do merocrine sweat glands primarily cool the body?
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Which glands are correctly described as compound alveolar glands producing milk?
Which glands are correctly described as compound alveolar glands producing milk?
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What role does the autonomic nervous system play in gland secretion?
What role does the autonomic nervous system play in gland secretion?
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What is the primary function of sensible perspiration?
What is the primary function of sensible perspiration?
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Which structure is produced in the nail root and is primarily dermal in origin?
Which structure is produced in the nail root and is primarily dermal in origin?
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Study Notes
Dermis
- Lies between the epidermis and hypodermis.
- Anchors accessory structures, including hair follicles and sweat glands.
- Consists of two layers: the papillary layer and the reticular layer.
Papillary Layer
- Superficial layer of the dermis.
- Composed of areolar tissue.
- Contains smaller capillaries, lymphatics, and nerve fibers.
- Contains dermal papillae that project between epidermal ridges.
Reticular Layer
- Deep layer of the dermis.
- Composed of dense irregular connective tissue.
- Contains larger blood vessels, lymphatics, and nerve fibers.
- Connected to the hypodermis.
Characteristics of the Dermis
- Strong due to collagen fibers.
- Elastic due to elastic fibers, which contribute to skin turgor.
Decreased Skin Turgor
- Reduced skin elasticity that leads to sagging and wrinkles.
- Caused by dehydration, hormonal changes, exposure to UV radiation, and aging.
Dermatitis
- Inflammation of the papillary layer.
- Caused by infection, radiation, mechanical irritation, or chemicals.
- Characterized by itching or other pain.
Lines of Cleavage (Langer's Lines)
- The collagen and elastic fibers in the dermis are arranged in parallel bundles.
- Resist force in a specific direction.
- Clinically important because parallel incisions remain shut and heal well while cuts made across the lines pull open and scar.
Dermal Blood Supply
- Arteries:
- Cutaneous plexus: network of arteries along the reticular layer.
- Papillary plexus: network of capillaries in the papillary layer.
- Veins:
- Venous plexus: receives blood from capillaries.
Contusion (Bruise)
- Blunt trauma to the skin that damages blood vessels.
- Blood leaks into the dermis, resulting in a "black and blue" discoloration.
Bed Sores (Decubitus Ulcers)
- Result from disturbances of dermal circulation.
- Affect the skin at pressure points.
- Prevention includes changing position frequently and using air mattresses.
Dermis & Nerve Supply
- Nerve fibers in the skin control blood flow, gland secretions, and sensations.
- Contains numerous receptors:
- Pacinian (lamellar) corpuscles: sense pressure and vibration.
- Meissner’s (tactile) corpuscles: sense light touch.
- Merkel discs: sense pressure, position, and deep touch.
- Ruffini (bulbous) corpuscles: sense skin stretch.
- Free nerve endings: sense pain and temperature.
Dermis at a Glance
- Provides mechanical strength, flexibility, and protection.
- Consists of two layers of connective tissue.
- Highly vascular.
- Contains a variety of sensory receptors.
Hypodermis
- Also known as subcutaneous tissue or superficial fascia.
- Not part of the skin; lies underneath the integument.
- Quite elastic and stabilizes the skin, allowing independent movement.
Structure of the Hypodermis
- Composed of areolar and adipose tissues.
- Connected to the reticular layer of the dermis by connective tissue fibers.
Clinical Importance of the Hypodermis
- Has few capillaries and no vital organs.
- Site of subcutaneous injections and liposuction.
Accessory Structures of the Integumentary System
- Hair.
- Glands (sebaceous, sweat, mammary, and ceruminous).
Hair
- Structure:
- Hair shaft: upper portion, sticks out of the integument.
- Hair root: lower portion, attached to the integument.
- Hair follicle: factory of hair, located in the dermis and wrapped with dense connective tissue.
- Accessory structures: sebaceous glands, arrector pili muscle, and connective tissue sheath.
Regions of the Hair
- Hair root: lower part, attached to the integument.
- Hair shaft: upper part, sticks out of the integument.
Layers in a Hair
- Medulla: central core, contains soft and flexible keratin.
- Cortex: middle layer, contains thick layers of hard keratin, giving hair its stiffness.
- Cuticle: outer layer, thin but tough, contains hard keratin.
Keratin
- Hair is keratinized during production:
- Medulla contains flexible soft keratin.
- Cortex and cuticle contain stiff hard keratin.
Hair Follicle
- Located deep in the dermis.
- Factory of hair.
- Wrapped in a dense connective tissue sheath.
- Base is surrounded by sensory nerves (root hair plexus).
Layers of the Hair Follicle
- Internal root sheath: surrounds the hair root and deeper part of the shaft.
- External root sheath: extends from the skin surface to the hair matrix.
- Glassy membrane: thickened, clear layer wrapped in the dense connective tissue sheath.
Hair Production by the Follicle
- Hair papilla: contains capillaries and nerves.
- Hair bulb: surrounds the papilla and produces:
- Hair layers.
- Hair matrix which produces hair cells.
Accessory Structures of Hair
- Arrector pili muscle: involuntary smooth muscle causing hair to stand up which produces "goose bumps."
- Sebaceous glands: secrete sebum (oil) to lubricate the hair and inhibit bacteria.
Location of Hair
- The human body is covered with hair except on the palms, soles, lips, and portions of the external genitalia (labia minora and penis).
Types of Hairs
- Vellus hairs: soft, fine hairs covering the body surface.
- Terminal hairs: heavy, pigmented hairs found on the head, eyebrows, and other areas after puberty (pubic, axillary).
Hair Color
- Melanin produced by melanocytes at the hair papilla determines hair color.
- Determined by genes.
Functions of Hair
- Provides protection and insulation.
- Guards openings against particles and insects.
- Sensitive to very light touch.
Integumentary Glands
- Sebaceous (oil) glands.
- Sweat glands.
- Mammary glands.
- Ceruminous glands.
Sebaceous Glands
- Simple branched alveolar glands.
- Holocrine glands, meaning they secrete sebum through the breakdown of their cells.
- Secrete sebum (oil).
Sebum
- Oily material containing lipids and other ingredients.
- Lubricates and protects the epidermis.
- Inhibits bacteria.
- Seborrheic dermatitis is an inflammation around hyperactive sebaceous gland.
Sweat Glands
- Simple coiled tubular glands.
- Produce sweat.
- Two types: merocrine (eccrine) and apocrine.
Merocrine Sweat Glands
- Widely distributed on the body surface, especially on palms and soles.
- Discharge directly onto the skin surface.
- Function:
- Excrete water, salts, and organic compounds.
- Cool down the skin.
- Flush microorganisms and harmful substances.
Apocrine Sweat Glands
- Found in the axilla, around the nipples, and the pubic region.
- Discharge onto hair follicles.
- Produce sticky and cloudy secretions, which are acted upon by bacteria to intensify their odor.
Mammary & Ceruminous Glands
- Mammary glands:
- Compound alveolar glands.
- Apocrine glands.
- Produce milk.
- Ceruminous glands:
- Simple coiled tubular glands.
- Modified apocrine sweat glands.
- Produce cerumen (earwax) that protects the eardrum.
Control of Glands
- Autonomic nervous system controls gland secretion:
- Global control: works simultaneously over the entire body.
- Regional control: sweating occurs locally (e.g., palms).
Skin & Thermoregulation
- Main function of sensible perspiration:
- Regulates body temperature.
- Works with the cardiovascular system.
- Skin plays a major role in controlling body temperature:
- Acts as a radiator.
- Removes heat from dermal circulation.
- Works by evaporation of sensible perspiration.
Nails
- Produced in the nail root, a deep epidermal fold near the bone.
Nails & Disease
- Clubbing: abnormal rounded nails seen in various diseases.
- Spoon nail (koilonychia): concave nails associated with iron deficiency.
- Psoriasis: chronic skin disease.
Skin Injuries & Repair
- Inflammatory phase:
- Bleeding occurs at the site of injury.
- Mast cells trigger an inflammatory response.
Abnormal Scars
- Hypertrophic scar: raised scar.
- Keloid: raised scar that extends beyond the original wound.
- Atrophic scar: sunken scar (e.g., healed acne).
- Stretch marks (striae gravidarum): thinned scar.
Burns & Scalds
- Result from denaturation of cell proteins.
- Dehydration, protein loss, and infection are a concern.
- Degrees:
- First degree: epidermis only.
- Second degree: epidermis and upper dermis, may include blisters.
- Third degree: full thickness, ± underlying tissues (fourth degree), skin grafting is necessary.
Rule of Nines
- Used to estimate burn damage by dividing the surface area into multiples of nine.
Effects of Aging
- Epidermal thinning.
- Decrease in:
- Number of Langerhans cells.
- Vitamin D3 production.
- Glandular activity.
- Blood supply.
- Function of hair follicles.
- Melanocyte activity.
- Elastic fibers.
- Slower repair rate.
Integument & Other Systems
- The integumentary system interacts with other systems in the body, including:
- Endocrine system: hormones influence skin growth and development.
- Nervous system: regulates temperature, controls blood flow, and transmits sensations.
- Immune system: protects against pathogens.
- Cardiovascular system: provides blood supply.
- Skeletal system: supports and protects the skin.
Summary
- The integumentary system comprises the skin, hair, glands (sweat, sebaceous, mammary, ceruminous), and nails.
- The skin consists of:
- Epidermis: thin outer layer made of epithelial tissue.
- Dermis: thicker inner layer composed of connective tissue.
Differences Between Thick & Thin Skin
- Thick skin: 5 epidermal layers, found on palms and soles, lacks hair follicles, and has more sweat glands.
- Thin skin: 4 epidermal layers, covers most of the body, has hair follicles, and fewer sweat glands.
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Description
Test your knowledge about the dermis, including its layers, characteristics, and conditions that affect skin turgor. This quiz covers key concepts such as the papillary and reticular layers, as well as dermatitis and skin aging. Perfect for students of anatomy or dermatology.