Questions and Answers
What is the primary reason why repetitive mechanical stresses applied to the integument stimulate cell division in the stem cells of the stratum basale?
To thicken the epidermis and improve its ability to withstand stress.
What is the key difference between regeneration and fibrosis in terms of tissue function?
Regeneration restores tissue function, while fibrosis does not.
What type of cells are responsible for producing collagen fibers in scar tissue during fibrosis?
Fibroblasts of connective tissue.
What is the temporary barrier that forms in the wound during the early stages of wound healing?
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What is the primary purpose of leukocytes in the wound during the early stages of wound healing?
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What is the significance of antibodies in the wound during the early stages of wound healing?
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What is the name of the process by which the skin responds to stressors, trauma, and damage?
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What is the significance of the stratum basale in the context of wound healing?
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What type of leukocytes clean the wound of cellular debris during the wound healing process?
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What type of tissue forms initially in a healing wound, characterized as vascular connective tissue?
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What process occurs due to epithelial cell division at the edge of the wound during the wound healing process?
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What autoimmune disease causes rapid overgrowth and overproduction of new skin cells, leading to patches of whitish, scaly skin?
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What factor determines the speed of skin repair and regeneration during wound healing?
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What integumentary system components are not repaired following severe damage to the integument?
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What is the role of fibroblasts in the wound healing process?
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What type of cell mistakenly attacks keratinocytes in psoriasis, leading to rapid overgrowth and overproduction of new skin cells?
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What is a common complication of skin repair and regeneration, especially in areas with fluid loss and infection?
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When does granulation tissue appear during wound healing of the skin?
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What is the primary cause of ingrown nails, and what are some potential complications if left untreated?
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What is nail pitting, and what is it often a symptom of?
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What is nail clubbing, and what is it often associated with?
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What is onychomycosis, and what are its typical symptoms?
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What is yellow nail syndrome, and what is it often a sign of?
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What is spoon nail, and what is it often a sign of?
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What are Beau's lines, and what do they indicate?
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Why is the nail body darker in color, while the free edge of the nail is lighter?
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What is the lunula, and where is it located?
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What is the eponychium, and where is it located?
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What is the primary function of the hair on the head?
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What type of hair replaces lanugo hair at birth?
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What is the role of the arrector pili?
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What is the hair bulb composed of?
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What is the function of the hair matrix?
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What is the outermost layer of the hair?
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What is the composition of the medulla?
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What are the two principal concentric layers of the hair follicle wall?
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What is the significance of the dermal papillae?
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At what stage of development does lanugo hair first appear?
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What is the primary function of hair within the nostrils?
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What is the role of hair follicles in sensory reception?
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What determines hair color?
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What is the longest phase of the hair growth cycle?
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What is the condition where the body mistakes selected hair follicles as foreign and attacks them?
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What is the condition where hair is lost from the crown region of the scalp?
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What is the term for excessive hairiness in areas that normally do not have terminal hair?
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Why does hair become lighter in color as people age?
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What is the normal rate of hair loss per day?
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What is the function of eyelashes?
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What is the primary cause of hirsutism?
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What are the two main types of exocrine glands found in the skin?
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What is the function of myoepithelial cells in sweat glands?
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What is the main function of merocrine sweat glands?
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Where are apocrine sweat glands typically located?
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What is the composition of sweat produced by merocrine sweat glands?
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What is the role of sweat gland secretions in protecting the skin?
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What would you expect to happen to sweat gland production and secretion when we are frightened or nervous?
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What is the significance of sebaceous glands in the skin?
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How do sweat glands respond to nervous system stimulation?
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How do cerumen and tiny hairs in the meatus work together to protect the eardrum?
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What is the main difference between mammary glands in males and females?
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How do apocrine sweat glands differ from merocrine sweat glands in terms of their secretions?
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What is the primary function of sebaceous glands, and where do they secrete their material?
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What complex interaction controls the development of mammary glands and their secretions?
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What is the mechanism by which apocrine and merocrine sweat glands produce their secretion?
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What is the main difference between the secretions produced by apocrine and merocrine sweat glands?
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What is the function of sebum produced by sebaceous glands?
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What is the term used to describe plugged ducts of sebaceous glands?
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What is the name of the glands located only in the external acoustic meatus that produce a waterproof earwax?
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What is the primary function of the mammary glands?
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What is the usual time period when sebaceous glands become active and produce secretions?
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What is the main difference between an open comedo and a closed comedo?
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What is the term used to describe a large, fluid-filled nodule that can become severely inflamed and painful?
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What is the significance of hormones in stimulating sebaceous gland secretion?
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What are the three integumentary structures derived from the epidermis?
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What is the primary function of nails?
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What are the three parts that form the nail plate?
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What is the significance of changes in the shape, structure, or appearance of the nails?
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What causes brittle nails?
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What is the composition of nails?
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During embryologic development, how do epidermal derivatives form?
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What is the nail bed?
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Study Notes
Repair and Regeneration of the Integumentary System
Distinguishing Between Regeneration and Fibrosis
- Regeneration: replacement of damaged or dead cells with the same cell type by cell division, restoring tissue function
- Fibrosis: replacement of damaged tissue with scar (fibrous) tissue, composed primarily of collagen fibers produced by fibroblasts, which binds damaged parts together but does not restore functional activities
Process of Wound Healing
- Cut blood vessels result in release of blood into the wound, bringing clotting proteins, leukocytes, and antibodies
- Blood clot forms, temporarily patching the edges of the wound together and acting as a barrier to prevent the entry of pathogens
- Macrophages and neutrophils clean the wound of cellular debris
- Cut blood vessels regenerate and grow in the wound
- Granulation tissue forms, a vascular connective tissue that initially forms in a healing wound
- Macrophages remove the clotted blood
- Fibroblasts produce new collagen fibers in the region
- Epithelial regeneration of the epidermis occurs due to epithelial cell division at the edge of the wound
- New epithelial cells migrate over the wound, moving internally to the now superficial remains of the clot (the scab)
- Connective tissue is replaced by fibrosis
Psoriasis
- A chronic autoimmune disease of the skin with periods of flare-ups and remissions
- T-lymphocytes mistakenly attack keratinocytes, causing rapid overgrowth and overproduction of new skin cells
- Normal sloughing-off cycle of keratinocytes is thrown out of balance, forming patches of whitish, scaly skin (plaques) on the epidermal surface
- Symptoms include itching, pain, and skin cracking and bleeding
- Treatments include topical corticosteroids, ultraviolet light therapy, and certain oral medications
Factors Affecting Skin Repair and Regeneration
- Extent of the injury: wider and deeper surface affected, longer it takes for skin to be repaired
- Severity of damage: increases susceptibility to complications due to fluid loss and infection
- Some integumentary system components may not be repaired following severe damage, including hair follicles, exocrine glands, nerves, and arrector pili muscle cells.
Integumentary Structures Derived from Epidermis
- Nails, hair, and exocrine glands of the skin are derived from the epithelium that forms the epidermis
- These structures are also known as epidermal derivatives or epidermal appendages of the integument
- They formed during embryologic development as portions of the epidermis invaginated into the dermis
Nails
- Nails are scalelike modifications of the stratum corneum layer of the epidermis that form on the dorsal edges of the fingers and toes
- Protect the distal tips of the digits during jumping, kicking, or catching
- Fingernails also assist in grasping objects
- Each nail has a distal light-colored free edge, a darker colored nail body, and a nail root, which is the proximal part embedded in the skin
- The nail body covers a layer of epidermis called the nail bed, which contains only the deeper, living cell layers of the epidermis
Nail Disorders
- Changes in the shape, structure, or appearance of the nails are clinically significant
- Nail disorders can be indicative of overall health
- Examples of nail disorders:
- Brittle nails: prone to vertical splitting and separation of the nail plate layers at the free edge
- Ingrown nails: painful condition where the edge of a nail digs into the skin around it
- Nail pitting: tiny depressions or shallow holes that appear in the nail body
- Nail clubbing: the tip of the finger enlarges and the edges of the nail grow and curve around the tip
- Onychomycosis: fungal infection that occurs in nails constantly exposed to warmth and moisture
- Yellow nail syndrome: slowed or stopped nail growth, often a sign of respiratory disease
- Spoon nails: concave shape of the nails, often a sign of iron deficiency
- Beau's lines: horizontal lines across the nail, indicating temporary interference with nail growth
- Vertical ridging of the nails: common and usually not indicative of a serious medical problem
Hair
- Found almost everywhere on the body except the palms of the hands and palmar surface of the fingers, the sides and soles of the feet and toes, the lips, and portions of the external genitalia
- General structure of hair and its relationship to the integument are shown in figure 6.10
- Hair is a derivative of the epithelium
- Composed of keratinized cells growing from hair follicles that extend into the dermis, and often deeper into the underlying subcutaneous layer
Hair Type and Distribution
- Three kinds of hair produced during our lives: lanugo, vellus, and terminal hair
- Lanugo: fine, unpigmented, downy hair that first appears on the fetus in the last trimester of development
- Vellus: fine, unpigmented or lightly pigmented hair that is the primary human hair and is found on the upper and lower limbs
- Terminal hair: coarser, pigmented, and longer than vellus, grows on the scalp, eyebrows, and eyelashes
Hair Structure and Follicles
- Three zones of a hair: the hair bulb, root, and shaft
- Hair bulb: consists of epithelial cells and is a swelling at the base where the hair originates in the dermis
- Hair root: zone of the hair extending from the bulb to the skin surface
- Hair shaft: third portion of the hair that extends beyond the skin surface
- Hair bulb contains living epithelial cells, whereas the root and shaft consist of dead epithelial cells
- Hair production involves a specialized type of keratinization that occurs within the hair matrix, a structure immediately adjacent to the hair papilla in the hair bulb
Hair Growth and Replacement
- Three stages of the hair growth cycle: anagen, catagen, and telogen
- Anagen phase: active phase of growth where living cells of the hair bulb are rapidly growing, dividing, and transforming into hair
- Catagen phase: brief regression period where cell division ceases and the follicle undergoes involution
- Telogen phase: resting phase and is usually the phase when the hair is shed
- Hair growth rate and the duration of the hair growth cycle vary; however, the scalp normally loses between 10 and 100 hairs per day
Exocrine Glands of the Skin
- Two types of exocrine glands: sweat glands and sebaceous glands
- Sweat glands: release their secretions directly onto the surface of the skin or into a hair follicle
- Sebaceous glands: produce an oily, waxy secretion called sebum that is usually discharged into a hair follicle and onto the hair itself
Sweat Glands
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Merocrine sweat glands: the most numerous and widely distributed sweat glands, discharge their secretions directly onto the surface of the skin
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Apocrine sweat glands: release their secretion into hair follicles in the axillae, around the nipples, in the pubic region, and in the anal region### Acne
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Acne can occur at any age, but it is most prevalent during teenage years
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There are different types of acne lesions, including comedos, papules, pustules, nodules, and cysts
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Comedos can be open (blackheads) or closed (whiteheads) and are caused by plugged sebaceous glands
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Papules are dome-shaped, fluid-filled lesions that can form red elevations on the skin
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Pustules are similar to papules but are filled with a mixture of white blood cells, dead skin cells, and bacteria
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Nodules are similar to pustules but extend deeper into the skin and can cause scarring
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Cysts are large, fluid-filled nodules that can become severely inflamed and painful, leading to scarring
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There are various medicinal treatments available for acne, including benzoyl peroxide, salicylic acid, antibiotics, and retinoids
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Untreated severe acne can lead to scarring, as can picking at acne lesions
Ceruminous Glands
- Ceruminous glands are modified apocrine sweat glands located in the external acoustic meatus (ear canal)
- These glands produce cerumen, a waterproof earwax that helps trap foreign particles and lubricate the ear canal
- Cerumen also helps prevent small insects from reaching the eardrum
Mammary Glands
- Mammary glands are modified apocrine sweat glands located in the breasts
- These glands become functional only in pregnant and lactating females, producing breast milk that nourishes offspring
- The development of mammary glands and their secretions are controlled by a complex interaction between gonadal and pituitary hormones
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Description
Explore the process of wound healing and regeneration in the integumentary system, distinguishing between regeneration and fibrosis.