Ch. 5 The Integumentary System Flashcards
What are the two main layers of the skin?
Epidermis and dermis
Which pigments contribute to skin color?
Melanin, carotene, and hemoglobin
What are the two layers of the dermis?
Papillary dermis and reticular dermis
What are nails primarily composed of?
Keratin
What is the primary function of sweat glands?
Help control body temperature
Which glands secrete sebum?
Sebaceous glands
Which type of cells make up hair?
Dead, keratinized cells
What are the functions of the skin?
Barrier, temperature regulation, sensation, excretion, and vitamin D synthesis
Integumentary System
The system consisting of the skin and its appendages (sweat and oil glands, hairs, and nails) that serves several protective functions.
What are the major layers of the epidermis?
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum
What factors determine skin color?
Melanin, carotene, and hemoglobin
Arrector Pili Muscle
A small muscle attached to hair follicles that causes hair to stand up (goosebumps) when contracted.
What are nails composed of?
Scale-like modifications of the epidermis
What is the function of sweat glands?
Help control body temperature
What is the function of sebaceous glands?
Secrete sebum
What are the three major types of skin cancer?
Basal cell carcinoma, squamous cell carcinoma, and melanoma
Why are serious burns life-threatening?
They can lead to severe fluid loss, infection, and shock.
Eccrine Glands
Sweat glands that are found all over the body and are important for regulating body temperature.
Apocrine Glands
Sweat glands found in specific areas such as the armpits and groin, which become active during puberty.
What are the two layers of the skin?
Epidermis and dermis
Which layer of the skin is composed mostly of dense connective tissue?
Dermis
What is another name for the subcutaneous tissue?
Hypodermis
What type of tissue primarily makes up the subcutaneous layer?
Adipose tissue
What is the primary function of the subcutaneous tissue?
Acts as a shock absorber and insulator
What is the outermost protective shield of the body called?
The epidermis
Which layer of the skin makes up the bulk of it and is composed mostly of dense connective tissue?
The dermis
How do nutrients reach the epidermis?
By diffusing through the tissue fluid from blood vessels in the dermis
What is another name for the subcutaneous tissue?
The hypodermis or the superficial fascia
What are the main components of the subcutaneous tissue?
Mostly adipose tissue with some areolar connective tissue
What are the functions of the subcutaneous tissue?
Storing fat, anchoring the skin to underlying structures, acting as a shock absorber, and reducing heat loss
Epidermis
The outermost protective shield of the body, composed of epithelial cells
Dermis
The tough, leathery layer of the skin composed mostly of dense connective tissue
Subcutaneous tissue
A layer of tissue lying just deep to the skin, consisting mostly of adipose tissue with some areolar connective tissue, and serving protective functions
What type of tissue composes the epidermis?
Keratinized stratified squamous epithelium
Which cell type in the epidermis produces keratin?
Keratinocytes
What is the primary function of melanocytes in the epidermis?
To synthesize the pigment melanin
Which layer of the epidermis is the deepest?
Stratum basale
Which cell type found in the epidermis is associated with immune system defenses?
Dendritic cells
What is the function of tactile epithelial cells in the epidermis?
To act as sensory receptors for touch
Which layer of the epidermis contains several layers of keratinocytes unified by desmosomes?
Stratum spinosum
Which layer of the epidermis is only found in thick skin?
Stratum lucidum
What is the primary function of the stratum corneum?
To protect the skin against abrasion and penetration
What is the primary function of keratinocytes?
To produce keratin, a fibrous protein that gives the epidermis its protective properties
What is the role of melanocytes in the epidermis?
To synthesize the pigment melanin, which protects the nucleus from UV radiation
Which cell type in the epidermis is associated with the immune system?
Dendritic cells (Langerhans cells)
What is the function of tactile epithelial cells?
They function as sensory receptors for touch
How many layers are present in thick skin?
Five layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum
Stratum corneum
The outermost layer of the epidermis, consisting of 20 to 30 layers of dead, keratin-filled cells
Stratum granulosum
A layer of the epidermis consisting of one to five layers of flattened cells where keratinization begins
Stratum spinosum
A layer of the epidermis several cells thick, containing keratinocytes unified by desmosomes and dendritic cells
Stratum basale
The deepest layer of the epidermis, consisting of a single row of stem cells that are actively mitotic
Melanocytes
Spider-shaped epithelial cells in the deepest layer of the epidermis that synthesize the pigment melanin
Dendritic cells
Star-shaped cells that arise from bone marrow and migrate to the epidermis, playing a key role in immune defense
Tactile epithelial cells
Cells present at the epidermal-dermal junction that function as sensory receptors for touch
What type of tissue composes the dermis?
Connective tissue
Which cells are typically found in the dermis?
Fibroblasts, macrophages, mast cells, and white blood cells
What is the primary function of the papillary dermis?
Allows phagocytes and other defensive cells to patrol for bacteria
What structures are found in the dermal papillae?
Capillary loops, free nerve endings, and tactile corpuscles
What is the primary function of friction ridges on the skin?
Enhance our ability to grip surfaces and contribute to our sense of touch
What type of connective tissue is the reticular dermis primarily composed of?
Dense irregular connective tissue
What is the significance of cleavage lines in the reticular dermis?
Surgical incisions parallel to cleavage lines heal better
What causes the formation of flexure lines on the skin?
Dermal folds that occur at or near joints
What are the two major layers of the dermis?
Papillary dermis and reticular dermis
What type of tissue composes the papillary dermis?
Areolar connective tissue
What is the main function of the reticular dermis?
Providing strength and resiliency to the skin
What type of connective tissue is found in the reticular dermis?
Dense irregular connective tissue
What are cleavage lines and why are they important in surgery?
Cleavage lines are separations between collagen fiber bundles in the reticular dermis. Surgical incisions parallel to these lines heal better.
What causes the formation of flexure lines?
The dermis is tightly secured to deeper structures, causing folds where the skin cannot slide easily.
Dermal Papillae
Peglike projections from the surface of the papillary dermis that indent the overlying epidermis.
Friction Ridges
Skin ridges formed by dermal ridges, enhancing grip and contributing to the sense of touch.
Striae
Silvery white scars caused by extreme stretching of the skin, commonly known as stretch marks.
What amino acid is melanin made from?
Tyrosine
Which enzyme is essential for melanin synthesis?
Tyrosinase
What pigment is responsible for the pinkish hue of fair skin?
Hemoglobin
Where does carotene tend to accumulate in the body?
Stratum corneum and subcutaneous fat
What skin condition is characterized by a yellow discoloration due to liver dysfunction?
Jaundice
What causes the skin to darken visibly when exposed to sunlight?
Melanin buildup
What is the main function of melanin in the skin?
Protecting DNA from UV radiation
What skin condition can indicate respiratory or cardiovascular problems?
Cyanosis
What pigment can be converted to vitamin A in the body?
Carotene
What are the three main pigments that determine skin color?
Melanin, carotene, and hemoglobin
Where is melanin pigment found in the skin?
In the deeper layers of the epidermis
Why do populations near the equator tend to have darker skin?
Greater protection from the sun is needed
What causes freckles and pigmented moles?
Local accumulations of melanin
What happens to melanin production when skin is exposed to sunlight?
Keratinocytes secrete chemicals that stimulate melanocytes, causing melanin buildup
What pigment gives fair skin its pinkish hue?
Hemoglobin
What is cyanosis and what can it indicate?
A bluish-gray tint of the skin indicating poorly oxygenated hemoglobin, possibly due to respiratory or cardiovascular problems
What skin color change can indicate liver dysfunction?
Yellowness or jaundice
What are ecchymoses and why are they significant in forensic medicine?
Bruises caused by damaged blood vessels leaking blood, significant due to their size, color, and shape
Melanin
A polymer made of tyrosine that ranges in color from reddish yellow to brownish black and determines skin color
Carotene
A yellow to orange pigment found in certain plant products that accumulates in the stratum corneum and subcutaneous fat
Hemoglobin
A crimson-colored oxygenated pigment in red blood cells that gives fair skin its pinkish hue
Cyanosis
A bluish-gray tint of the skin due to poorly oxygenated hemoglobin, indicating possible respiratory or cardiovascular issues
Jaundice
A yellow discoloration of the skin and eyes due to the accumulation of bilirubin, indicating liver dysfunction
What are the three main regions of a hair?
Root, shaft, and bulb
What type of keratin is found in hair?
Hard keratin
Which part of the hair contains soft keratin?
Medulla
What is the function of the arrector pili muscle?
Pulls the hair follicle upright and produces goose bumps
What pigment is responsible for red hair color?
Pheomelanin
What is the main function of hair in humans?
To sense insects on the skin before they bite or sting
What happens to hair when melanin production decreases?
Hair turns gray or white
What is the role of the hair papilla?
Supplies nutrients to the growing hair and signals it to grow
Which layer of the hair follicle is derived from the dermis?
Peripheral connective tissue sheath
What type of hair is found on the scalp?
Terminal hair
What are the main parts of a hair follicle?
Peripheral connective tissue sheath, glassy membrane, and epithelial root sheath
What is the function of the arrector pili muscle?
It pulls the hair follicle upright and produces goose bumps in response to cold or fear.
What are the three concentric layers of a hair?
Medulla, cortex, and cuticle
What determines the texture of hair (kinky, wavy, straight)?
The shape of the hair shaft: flat and ribbonlike for kinky, oval for wavy, and round for straight.
Medulla (Hair)
The central core of a hair, consisting of large cells and air spaces, and containing soft keratin.
Cortex (Hair)
A bulky layer surrounding the medulla, consisting of several layers of flattened cells.
Cuticle (Hair)
The outermost layer of a hair, formed from a single layer of cells overlapping one another like shingles on a roof.
What causes hair to turn gray or white?
Decreased melanin production and the replacement of melanin by air bubbles in the hair shaft.
What are the two types of hair found on the human body?
Vellus hair and terminal hair
Hair papilla
A dermal papilla that protrudes into the hair bulb, containing capillaries that supply nutrients to the growing hair.
What is the main function of hair on the human scalp?
To guard the head against physical trauma, heat loss, and sunlight.
What is the role of melanocytes in hair follicles?
They produce hair pigment and transfer it to the cortical cells.
What is the main visible component of the nail that ends in the free edge?
Nail plate
What is the thickened proximal portion of the nail bed responsible for nail growth?
Nail matrix
What is the white crescent-shaped area at the base of the nail called?
Lunule
What substance hardens both hair and nails?
Keratin
What is the name of the skin fold that projects onto the nail body as the cuticle?
Proximal nail fold
What condition might yellow-tinged nails indicate?
Respiratory or thyroid gland disorder
What is the term for an outward concavity of the nail that may signal an iron deficiency?
Koilonychia
What is the primary function of nails?
To form a clear protective covering on the dorsal surface of the distal part of a finger or toe.
What are the main visible components of the nail?
The nail plate, free edge, nail bed, cuticle, proximal nail fold, nail root, and nail matrix.
What substance hardens both hair and nails?
Keratin.
What is the lunule?
The white crescent-shaped area at the base of the nail, lying over the thick nail matrix.
What is the hyponychium?
The thickened region beneath the free edge of the nail where dirt and debris tend to accumulate.
What might yellow-tinged nails indicate?
A respiratory or thyroid gland disorder, or a fungal infection.
What is koilonychia and what might it indicate?
Koilonychia, or ‘spoon nail,’ is an outward concavity of the nail that may signal an iron deficiency.
What are Beau’s lines and what might they indicate?
Horizontal lines across the nails that can be a sign of severe illness affecting the whole body, such as uncontrolled diabetes, a heart attack, or cancer chemotherapy.
Nail Matrix
The thickened proximal portion of the nail bed responsible for nail growth.
Cuticle (Eponychium)
The proximal nail fold that projects onto the nail body.
Nail Bed
The bed of epidermis on which the nail rests, containing only the deeper layers of the epidermis.
Lunule
The white crescent-shaped area at the base of the nail, lying over the thick nail matrix.
What is the primary function of eccrine sweat glands?
Evaporative cooling
Where are eccrine sweat glands most abundant?
Palms, soles of the feet, and forehead
What substance do sebaceous glands secrete?
Sebum
Which glands are responsible for body odor?
Apocrine sweat glands
What is the primary component of eccrine sweat?
Water
What is the function of ceruminous glands?
Produce earwax
What is the pH range of normal sweat?
4 to 6
What triggers the activity of apocrine sweat glands?
Male sex hormones (androgens)
What is the role of sebum?
Lubricate skin and hair
What are the two types of sweat glands found in the human body?
Eccrine and apocrine glands
Where are apocrine sweat glands primarily located?
Axillary and anogenital areas
What is the main role of sebum?
To lubricate skin and hair, prevent water loss, and provide antibacterial properties
What triggers the contraction of myoepithelial cells in sweat glands?
Stimulation by the nervous system
What is the composition of eccrine sweat?
99% water, salts, metabolic wastes, and dermcidin
What is the pH range of normal sweat?
Between 4 and 6
What are ceruminous glands and what do they produce?
Modified apocrine glands that produce earwax (cerumen)
What is the function of mammary glands?
To secrete milk
Eccrine sweat glands
Sweat glands that are abundant on the palms, soles of the feet, and forehead, and primarily function in evaporative cooling
Apocrine sweat glands
Sweat glands located in the axillary and anogenital areas that secrete a viscous fluid into hair follicles
Sebaceous glands
Oil glands that secrete sebum to lubricate skin and hair, and provide antibacterial properties
Sebum
An oily substance secreted by sebaceous glands that lubricates skin and hair, and has antibacterial properties
Myoepithelial cells
Specialized cells that contract when stimulated by the nervous system to expel sweat from sweat glands
What are the three types of barriers that the skin constitutes?
Chemical, physical, and biological
What substance in sweat helps kill bacteria?
Dermcidin
What is the role of melanin in the skin?
Provides a chemical pigment shield to prevent UV damage
Which cells in the skin secrete natural antibiotics called defensins?
Skin cells
What is the primary function of the stratum corneum in the skin?
Acts as a physical barrier
What type of substances can penetrate the skin in limited amounts?
Lipid-soluble substances
What happens to dermal blood vessels when the body is exposed to cold temperatures?
They constrict
Which cutaneous receptor is responsible for sensing deep pressure?
Lamellar (Pacinian) corpuscles
What vitamin is synthesized by the skin when exposed to sunlight?
Vitamin D
What percentage of the body’s blood volume can the dermal vascular supply hold?
5%
What are the three types of barriers provided by the skin?
Chemical, physical, and biological barriers
How does the skin contribute to body temperature regulation when the external environment is cold?
By constricting dermal blood vessels
What is insensible perspiration?
The routine and unnoticeable sweating of about 500 ml per day under normal conditions
What triggers the immune response in the skin?
Dendritic cells capturing foreign invaders and presenting them to other immune cells
What role does melanin play in protecting the skin?
It provides a chemical pigment shield to prevent UV damage to skin cells
What is the function of keratin in the skin?
Keratinized cells harden and waterproof the skin, providing a physical barrier
Insensible perspiration
The routine and unnoticeable sweating of about 500 ml per day under normal conditions
Dendritic cells
Immune cells in the epidermis that capture foreign invaders and trigger an immune response
Cathelicidins
Protective peptides released by wounded skin to prevent infection by group A streptococcus bacteria
Sensible perspiration
Noticeable sweating that occurs when body temperature rises, potentially up to 12 liters per day
Exteroceptors
Cutaneous sensory receptors that respond to stimuli arising outside the body
What is the most common type of skin cancer?
Basal cell carcinoma
Which type of skin cancer is the most dangerous due to its high metastatic potential?
Melanoma
What is the primary risk factor for developing skin cancer?
Exposure to UV radiation
Which layer of the skin does basal cell carcinoma originate from?
Stratum basale
What is a common appearance of squamous cell carcinoma?
Scaly reddened papule
What does the ‘A’ stand for in the ABCD rule for recognizing melanoma?
Asymmetry
What is the immediate threat to life from severe burns?
Loss of body fluids
Which degree of burn involves the entire thickness of the skin?
Third-degree burn
What is the main treatment for third-degree burns?
Skin grafting
What is the ‘rule of nines’ used for?
Estimating the extent of burns
Which type of skin cancer is the most dangerous and why?
Melanoma, because it is highly metastatic and resistant to chemotherapy
What is the main risk factor for developing skin cancer?
Exposure to UV radiation in sunlight and tanning beds
What are the characteristics of basal cell carcinoma?
Shiny, dome-shaped nodules that later develop a central ulcer with a pearly, beaded edge
What are the ABCD rules for recognizing melanoma?
Asymmetry, Border irregularity, Color, Diameter
What immediate threat do severe burns pose to the body?
Catastrophic loss of body fluids leading to dehydration, electrolyte imbalance, renal failure, and circulatory shock
How are burns classified?
As first-degree, second-degree, or third-degree based on their severity (depth)
What is the rule of nines used for?
Estimating the percentage of body surface area affected by burns
Basal cell carcinoma
The least malignant and most common type of skin cancer, arising from stratum basale cells
Squamous cell carcinoma
A type of skin cancer arising from the keratinocytes of the stratum spinosum
Melanoma
A dangerous type of skin cancer originating from melanocytes, known for being highly metastatic and resistant to chemotherapy
First-degree burn
A burn that only damages the epidermis, causing localized redness, swelling, and pain
Second-degree burn
A burn that injures the epidermis and the upper region of the dermis, characterized by blisters, redness, and pain
Third-degree burn
A full-thickness burn involving the entire thickness of the skin, often requiring skin grafting
From which embryonic layer does the epidermis develop?
Ectoderm
By which month of development is the skin fairly well formed?
Fourth month
What is the name of the downy coat of delicate colorless hairs that covers the fetus during the fifth and sixth months?
Lanugo coat
What substance covers a newborn’s skin and protects it within the amnion?
Vernix caseosa
What are the small white spots on a newborn’s forehead and nose called?
Milia
Why do people who grow up in hot climates have more active sweat glands?
Because the number of functioning sweat glands increases in the first two years after birth and is determined by climate
What skin condition commonly appears during adolescence due to increased activity of sebaceous glands?
Acne
What happens to the skin as old age approaches?
The rate of epidermal cell replacement slows, the skin thins, and susceptibility to bruises and injuries increases
What leads to the intolerance to cold commonly seen in elderly people?
Diminished subcutaneous fat layer
What is one of the best ways to slow the process of skin aging?
Shielding your skin from the sun’s rays of both UVA and UVB light
By what month of development is the skin fairly well formed?
By the end of the fourth month
What substance covers a newborn’s skin at birth?
Vernix caseosa
What skin condition often appears during adolescence due to increased activity of sebaceous glands?
Acne
What happens to the skin as old age approaches?
The rate of epidermal cell replacement slows, the skin thins, and its susceptibility to bruises and other injuries increases
What are the effects of declining levels of sex hormones on elderly skin?
Similar fat distribution in elderly men and women, leading to wrinkling
What is one of the best ways to slow the process of skin aging?
Shield your skin from the sun’s rays of both UVA and UVB light
Lanugo coat
A downy coat of delicate colorless hairs that covers the fetus during the fifth and sixth months of development
Vernix caseosa
A white, cheesy-looking substance produced by the sebaceous glands that protects the fetus’s skin within the water-filled amnion
Milia
Small white spots on a newborn’s forehead and nose caused by accumulations in the sebaceous glands
Dermatitis
Various kinds of skin inflammation that become more common as the skin ages
Ectoderm
The embryonic layer from which the epidermis develops
Which body system provides support for the skin?
Skeletal system
What effect do active muscles have on the skin?
Increase blood flow to the skin and may activate sweat glands
Which system regulates the diameter of blood vessels in the skin?
Nervous system
What do androgens produced by the endocrine system activate?
Apocrine and sebaceous glands
How does the cardiovascular system support the skin?
Transports oxygen and nutrients to the skin and removes wastes
What role do dendritic cells and macrophages in the skin play?
Help activate the immune system
What does the respiratory system provide to skin cells?
Oxygen
What does the digestive system provide to the skin?
Needed nutrients
What role does the muscular system play in relation to the skin?
Active muscles generate large amounts of heat, which increases blood flow to the skin and may activate sweat glands.
How does the nervous system contribute to thermoregulation?
The nervous system regulates the diameter of blood vessels in the skin and activates sweat glands.
Cutaneous sensory receptors
Receptors located in the skin that detect touch, pressure, pain, and temperature.
What is the primary function of sebaceous glands?
Secrete sebum
What type of cells are most abundant in the epidermis?
Keratinocytes
Which layer of the epidermis is responsible for new cell production?
Stratum basale
What pigment is primarily responsible for protecting the skin from UV radiation?
Melanin
What is the main function of eccrine sweat glands?
Thermoregulation
What type of burn requires grafting for successful recovery?
Third-degree burn
What is the actively growing region of a nail called?
Nail matrix
Epidermis
The outer layer of the skin, composed of keratinized stratified squamous epithelium
What is the primary function of sebaceous glands?
To secrete sebum, which lubricates the skin and hair
Melanin
A pigment produced by melanocytes that protects the skin from UV radiation
What are the two types of sweat glands?
Eccrine and apocrine sweat glands
What causes the formation of fingerprints?
The friction ridges formed by dermal and epidermal ridges
What is the main threat in severe burns after the initial injury?
Overwhelming bacterial infection
Which layer of the dermis is responsible for forming tension lines?
The reticular dermis
Vernix Caseosa
A protective, waxy substance produced by fetal sebaceous glands
What are the main pigments that determine skin color?
Melanin and carotene
Liliana’s epidermal layer has been damaged. Which statement best explains the significance of this damage?
It’s significant because the cells of the epidermis protect against evaporative water loss, UV radiation, and infection.
Liliana’s cyanosis is clinically significant because:
It indicates that her blood is low in oxygen.
Why might the cut extending along Liliana’s temple heal with little scarring compared to the one on her cheek?
The orientation of the cut along natural skin lines reduces scarring.
What is the significance of damage to the epidermal layer?
The cells of the epidermis protect against evaporative water loss, UV radiation, and infection.
What might act to prevent further bacterial invasion if bacteria have penetrated the dermis?
Remaining skin defenses such as immune cells and antimicrobial peptides might act to prevent further bacterial invasion.
Why might the cut on Liliana’s cheek be more likely to scar than the one on her temple?
The cut on her cheek is more likely to scar because it is deeper and vertical, which affects the natural alignment of skin fibers and healing process.
What does Liliana’s cyanosis indicate?
It indicates that her blood is low in oxygen.
Cyanosis
A bluish discoloration of the skin resulting from poor circulation or inadequate oxygenation of the blood.
Epidermis
The outermost layer of skin that provides a barrier to infection, UV radiation, and water loss.
Why might skin secretions be important for wound healing?
Skin secretions contain antimicrobial properties and help maintain a moist environment, which can facilitate wound healing.
Burn
Tissue damage inflicted by intense heat, electricity, radiation, or certain chemicals, all of which denature cell proteins and kill cells in the affected areas.
Second-degree burns
A burn in which the epidermis and the upper region of the dermis are damaged.
Cutaneous sensory receptors
Receptors located throughout the skin that respond to stimuli arising outside the body; part of the nervous system.
Sebaceous glands
Epidermal glands that produce an oily secretion called sebum.
First-degree burns
A burn in which only the epidermis is damaged.
Rule of nines
Method of computing the extent of burns by dividing the body into a number of areas, each accounting for 9% (or a multiple thereof) of the total body area.
Hemoglobin
Oxygen-transporting protein of erythrocytes.
Cardiovascular System
Organ system that distributes the blood to deliver nutrients and remove wastes.
Hair follicles
Structure with outer and inner root sheaths extending from the epidermal surface into the dermis and from which new hair develops.
Third-degree burns
A burn that involves the entire thickness of the skin; also called a full-thickness burn. Usually requires skin grafting.
Keratin
Fibrous protein found in the epidermis, hair, and nails that makes those structures hard and water resistant; precursor is keratohyaline.
Apocrine sweat glands
The less numerous type of sweat gland; produces a secretion containing water, salts, proteins, and fatty acids.
Melanin
Dark pigment formed by cells called melanocytes; imparts color to skin and hair.
Vascular
Pertaining to blood vessels or richly supplied with blood vessels.
Ulcer
Lesion or erosion of the mucous or cutaneous membrane, such as a gastric ulcer of the stomach.
Mammary glands
Milk-producing glands of the breast.
Melanoma
Cancer of the melanocytes; can begin wherever there is pigment.
Arrector pili
Tiny, smooth muscles attached to hair follicles; contraction causes the hair to stand upright.
Subcutaneous tissue
Tissue just deep to the skin; consists of adipose plus some areolar connective tissue. Also called hypodermis or superficial fascia.
Tumor
An abnormal growth of cells; a swelling; may be cancerous.
Alopecia
Baldness.
Epidermis
Superficial layer of the skin; composed of keratinized stratified squamous epithelium.
Muscular System
The organ system consisting of the skeletal muscles of the body and their connective tissue attachments.
Carotene
Yellow to orange pigment that accumulates in the stratum corneum epidermal layer and in fatty tissue of the subcutaneous tissue.
Dermis
Layer of skin deep to the epidermis; composed mostly of dense irregular connective tissue.
Sweat glands
Epidermal gland that produces sweat. Also called sudoriferous gland.
Dendritic cells
Protective cells that engulf antigens, migrate to lymph nodes, and present the antigen to T cells, causing them to activate and mount an immune response; those in the skin are sometimes called Langerhans cells.
Eccrine sweat glands
Sweat glands abundant on the palms, soles of feet, and the forehead. Also called merocrine sweat glands.
Sebum
Oily secretion of sebaceous glands.
Fascia
Layers of fibrous tissue covering and separating muscle.
Proximal
Toward the attached end of a limb or the origin of a structure.
Anucleate cell
A cell without a nucleus.
What are the two primary layers of the skin?
Epidermis and dermis
Which layer of the skin is primarily composed of epithelial cells and serves as the outermost protective shield?
Epidermis
The dermis is known for being:
A tough, leathery layer composed mostly of dense connective tissue.
How do nutrients reach the epidermis?
By diffusing through tissue fluid from blood vessels in the dermis.
Which layer of the skin is vascularized, allowing for nutrient diffusion to the epidermis?
Dermis
What is the primary function of the subcutaneous tissue?
To act as a shock absorber and an insulator that reduces heat loss.
The subcutaneous tissue is also known as:
Hypodermis
How does the subcutaneous tissue contribute to the skin’s protective functions?
By anchoring the skin to underlying structures, allowing it to slide over them.
Why is the skin considered an architectural marvel?
Because it covers the entire body and serves as a protective barrier.
What would likely happen without our skin’s protective barrier?
We would quickly fall prey to harmful bacteria and perish from water and heat loss.
Which cell type is primarily responsible for producing keratin in the epidermis?
Keratinocytes
What is the main function of melanocytes in the epidermis?
To synthesize the pigment melanin, which protects against UV radiation
Dendritic cells in the epidermis are primarily involved in which of the following processes?
Activating the immune system by ingesting foreign substances
Which layer of the epidermis is directly responsible for the generation of new keratinocytes through mitosis?
Stratum basale
In which layer of the epidermis does keratinization begin, characterized by the accumulation of keratohyaline granules?
Stratum granulosum
The stratum lucidum is found exclusively in which type of skin?
Thick skin covering areas subject to abrasion
What is the primary function of the glycolipids secreted by cells in the stratum granulosum?
To slow water loss across the epidermis
The stratum corneum is characterized by which of the following features?
A broad zone of flattened, anucleate cells thick with keratin
What triggers the accelerated production of cells and keratin formation in the epidermis?
Persistent friction, such as from a poorly fitting shoe
Approximately how often is the epidermis completely renewed?
Every 25 to 45 days
The process by which tactile epithelial cells function as sensory receptors for touch involves their association with what type of nerve ending?
A disclike sensory nerve ending
What types of cells are typically found in the dermis?
Fibroblasts, macrophages, mast cells, and white blood cells
Which of the following best describes the matrix of the dermis?
A semifluid matrix embedded with fibers that binds the body together
The dermis is primarily made up of which type of tissue?
Connective tissue
What is the primary type of connective tissue found in the papillary dermis?
Areolar connective tissue
The papillary dermis is characterized by which of the following features?
Fine interlacing collagen and elastic fibers forming a loosely woven mat
What function do the dermal papillae serve?
They indent the overlying epidermis and contain capillary loops and nerve endings
What percentage of the dermis thickness is accounted for by the reticular dermis?
About 80%
The reticular dermis is mainly composed of which type of connective tissue?
Dense irregular connective tissue
What is the significance of cleavage lines in the reticular dermis for surgical procedures?
Incisions made parallel to these lines heal more readily
What role do collagen fibers in the dermis play?
They give skin strength and resiliency to prevent minor injuries
How do elastic fibers contribute to the skin’s properties?
They provide the stretch-recoil properties of skin
What causes the formation of flexure lines in the skin?
Dermal folds occurring at or near joints due to the skin being tightly secured to deeper structures
Which enzyme is crucial for the synthesis of melanin?
Tyrosinase
Why do populations closer to the equator generally have darker skin?
They produce and retain more and darker melanosomes
What is the significance of carotene in the skin?
It can be converted to vitamin A, essential for epidermal health
Where does carotene tend to accumulate in the body?
In the stratum corneum and subcutaneous fat
What contributes to the pinkish hue of fair skin?
The color of oxygenated hemoglobin showing through the skin
Why is the epidermis of light-skinned individuals nearly transparent?
Because it has only small amounts of melanin
How can changes in skin color serve as clinical signs of certain diseases?
By reflecting abnormalities in melanin, carotene, or hemoglobin levels
What might a substantial buildup of melanin in the skin indicate?
Prolonged exposure to sunlight
Freckles and pigmented nevi (moles) are primarily caused by:
Local accumulations of melanin
What are the chief regions of a hair?
Root and shaft
What is the primary function of the arrector pili muscle in humans?
To make the hair stand upright and produce goosebumps
What determines the color of the hair?
The concentration of melanin
Which type of hair is described as pale and fine?
Vellus hair
During which phase does a hair follicle shrink and the hair matrix becomes inactive?
Resting phase
What is the role of the hair papilla?
To supply nutrients to the growing hair
Which layer of the hair follicle is a direct continuation of the epidermis?
Epithelial root sheath
What happens when the hair cuticle wears away at the tip of the hair shaft?
Keratin fibrils in the cortex and medulla frizz, creating “split ends”
What is the most common type of baldness characterized by a response to androgens?
Male pattern baldness
What is a key factor in the development of male pattern baldness?
Shorter hair growth cycles in response to androgens
How do treatments for male pattern baldness primarily function?
By inhibiting the production of androgens or increasing blood flow to hair follicles
What is the primary function of nails on the fingers or toes?
To provide a clear protective covering on the dorsal surface of the distal part of a finger or toe
Nails are made of what type of keratin?
Hard keratin
Which part of the nail is responsible for its growth?
The nail matrix
What is the term for the white crescent visible at the base of the nail?
Lunule
The nail rests on a bed of epidermis called the:
Nail bed
The thickened region beneath the free edge of the nail where dirt and debris tend to accumulate is called the:
Hyponychium
What is the visible attached portion of the nail called?
Nail plate or body
The proximal nail fold projects onto the nail body as the:
Cuticle or eponychium
Nails normally appear pink because of:
The rich bed of capillaries in the underlying dermis
The proximal and lateral borders of the nail are overlapped by skin folds called:
Nail folds
Which of the following best describes the primary function of eccrine sweat glands?
To prevent the body from overheating by producing sweat
Sebaceous glands are primarily responsible for:
Secreting sebum, an oily substance that lubricates the skin and hair
What is the main difference between the secretions of eccrine and apocrine sweat glands?
Eccrine secretions are mostly water, while apocrine secretions include fatty substances and proteins
Eccrine sweat glands are characterized by:
The secretion of a hypotonic filtrate of the blood
Apocrine sweat glands begin to function:
Under the influence of male sex hormones at puberty
Which statement accurately contrasts eccrine and apocrine sweat glands?
Apocrine glands secrete a milky or yellowish color secretion, while eccrine glands do not
The primary function of sebaceous glands is to:
Secrete sebum, which lubricates and protects the skin and hair
Sebaceous glands are not found in which of the following areas?
The thick skin of the palms and soles
How do sebaceous glands release their product?
By bursting of engorged central cells, releasing sebum
Ceruminous glands are specialized sweat glands that:
Produce cerumen, or earwax, in the external ear canal
The primary role of mammary glands is to:
Produce milk
Which of the following is a function of the secretion produced by ceruminous glands?
Deterring insects and blocking foreign material in the ear
Which of the following is NOT a function of the skin?
Nutrient storage
How does the skin contribute to body temperature regulation?
By dilating dermal blood vessels to release heat
What role does the skin play in metabolic functions?
Converts cholesterol to a vitamin D precursor when exposed to sunlight
What type of barrier do skin secretions and melanin provide?
Chemical barrier
Which of the following best describes the physical barrier function of the skin?
Blocks most diffusion of water and water-soluble substances between cells
Dendritic cells and macrophages are part of which type of skin barrier?
Biological barrier
Which type of cutaneous receptor is primarily responsible for detecting deep pressure?
Lamellar (Pacinian) corpuscles
Free nerve endings in the skin are sensitive to:
Painful stimuli such as extreme heat or cold
Tactile epithelial cells are involved in:
Detecting caresses or the feel of clothing against the skin
The skin assists in the excretion of:
Nitrogen-containing wastes such as urea
How does the skin act as a blood reservoir?
By holding about 5% of the body’s entire blood volume
What is the most important risk factor for developing skin cancer?
Exposure to UV radiation
Which type of skin cancer is known for being the least malignant but most common?
Basal cell carcinoma
Melanoma is particularly dangerous because it is:
Highly metastatic and resistant to chemotherapy
The ABCD rule is used to:
Recognize signs of melanoma
Why are serious burns considered life-threatening?
They lead to dehydration and electrolyte imbalance
A burn that damages only the epidermis is classified as a:
First-degree burn
Third-degree burns are characterized by:
Destruction of the entire thickness of the skin
The “rule of nines” is used to:
Estimate the percentage of body surface burned
Which condition makes burns critical and requires immediate medical attention?
Over 25% of the body has second-degree burns
In the treatment of burns, what is the primary reason for administering intravenous (IV) fluids?
To replace lost body fluids and prevent renal failure
The leading cause of death in burn victims, after the initial crisis, is:
Sepsis
Skin grafting is advised for:
Third-degree burns
By the end of which month of development is the skin fairly well formed, including the development of fingerprints and dermal papillae?
Fourth month
What substance covers a newborn’s skin, providing protection within the amniotic sac?
Vernix caseosa
Small white spots on the forehead and nose of newborns, which normally disappear by the third week, are called:
Milia
During adolescence, an increase in the activity of which glands contributes to oilier skin and the appearance of acne?
Sebaceous glands
What is a common skin condition in old age due to the clumping of elastic fibers and reduction in collagen fibers?
Wrinkling
Which factor contributes to the increased risk and incidence of skin cancer in elderly individuals?
Decreasing numbers of melanocytes and dendritic cells
How can the aging process of the skin be slowed down, according to the text?
Shielding the skin from the sun’s rays
What change in hair is noted by the age of 50 according to the passage?
Marked decline in the number of active hair follicles
What is the primary cause of albinism?
A lack of tyrosinase, leading to an inability to synthesize melanin
Alopecia areata is characterized by which of the following?
The immune system attacking the hair follicles, leading to hair loss
What common factor contributes to the development of boils and carbuncles?
Bacterial infection in hair follicles and sebaceous glands
Cold sores are primarily caused by which of the following?
A herpes simplex virus infection
Contact dermatitis results from exposure to:
Chemicals that provoke an allergic response
Decubitus ulcers, also known as bedsores, are caused by:
Continuous pressure leading to interference with blood supply
Eczema is commonly treated by:
Methods used for other allergic disorders
Epidermolysis bullosa is characterized by:
Lack of cohesion between skin layers due to faulty synthesis of skin components
Impetigo, a contagious skin condition, is caused by:
A staphylococcus bacterial infection
The primary symptom of porphyria related to skin is:
Skin sensitivity to sunlight leading to lesions and scarring
Psoriasis is an autoimmune condition that can be triggered by:
Emotional upset and stress
Rosacea is aggravated by all of the following EXCEPT:
Hot beverages and alcohol
Vitiligo is characterized by:
Unpigmented skin regions surrounded by normally pigmented areas
Scleroderma affects the skin by:
Producing stiff, hardened skin due to abnormal collagen amounts
The branch of medicine that deals with disorders of the skin is called:
Dermatology
Which two primary layers constitute the skin?
Epidermis and dermis
What is the primary function of melanin in the skin?
To protect keratinocyte nuclei from UV radiation
Which layer of the epidermis is absent in thin skin?
Stratum lucidum
What type of tissue primarily composes the dermis?
Dense irregular connective tissue
Which pigment is responsible for the yellow-orange coloration of the skin?
Carotene
Emotional states can affect skin color. Which of the following is not a color change associated with emotional states or disease?
Albinism
What is the primary component of hair?
Keratinized cells
At what stage of life do coarser, darker terminal hairs replace fine vellus hairs in certain body regions?
Puberty
What part of the nail is responsible for its growth?
Nail matrix
Which type of sweat gland plays a key role in thermoregulation?
Eccrine
What is the primary secretion of sebaceous glands?
Sebum
Which of the following is not a function of the skin?
Vitamin C synthesis
What is the most common cause of skin cancer?
Exposure to ultraviolet radiation
Which degree of burn requires grafting for successful recovery?
Third degree
What significant change occurs in the skin at puberty?
Increase in sebaceous gland activity
