Integumentary System: Repair and Regeneration

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?

A blood clot. Signup and view all the answers

What is the primary purpose of leukocytes in the wound during the early stages of wound healing?

To combat infection and prevent the spread of pathogens. Signup and view all the answers

What is the significance of antibodies in the wound during the early stages of wound healing?

They help combat infection by binding to pathogens. Signup and view all the answers

What is the name of the process by which the skin responds to stressors, trauma, and damage?

Regeneration and fibrosis. Signup and view all the answers

What is the significance of the stratum basale in the context of wound healing?

It contains stem cells that can divide to replace damaged cells. Signup and view all the answers

What type of leukocytes clean the wound of cellular debris during the wound healing process?

Macrophages and neutrophils Signup and view all the answers

What type of tissue forms initially in a healing wound, characterized as vascular connective tissue?

Granulation tissue Signup and view all the answers

What process occurs due to epithelial cell division at the edge of the wound during the wound healing process?

Epithelial regeneration of the epidermis Signup and view all the answers

What autoimmune disease causes rapid overgrowth and overproduction of new skin cells, leading to patches of whitish, scaly skin?

Psoriasis Signup and view all the answers

What factor determines the speed of skin repair and regeneration during wound healing?

The extent of the injury Signup and view all the answers

What integumentary system components are not repaired following severe damage to the integument?

Hair follicles, exocrine glands, nerves, and the arrector pili muscle cells Signup and view all the answers

What is the role of fibroblasts in the wound healing process?

Producing new collagen fibers in the dermis Signup and view all the answers

What type of cell mistakenly attacks keratinocytes in psoriasis, leading to rapid overgrowth and overproduction of new skin cells?

T-lymphocyte Signup and view all the answers

What is a common complication of skin repair and regeneration, especially in areas with fluid loss and infection?

Infection Signup and view all the answers

When does granulation tissue appear during wound healing of the skin?

Deep in the wound Signup and view all the answers

What is the primary cause of ingrown nails, and what are some potential complications if left untreated?

Overly tight shoes and improper trimming of the nails. Infection. Signup and view all the answers

What is nail pitting, and what is it often a symptom of?

Tiny depressions or shallow holes in the nail body. Psoriasis, alopecia areata, dermatitis, or a connective tissue disorder. Signup and view all the answers

What is nail clubbing, and what is it often associated with?

The tip of the finger enlarges, and the edges of the nail grow and curve around the tip. Hypoxia, smoking, cardiovascular disease, and diabetes. Signup and view all the answers

What is onychomycosis, and what are its typical symptoms?

A fungal infection that occurs in nails constantly exposed to warmth and moisture. Yellowish discoloration, thickened nail, and brittle, cracked edges. Signup and view all the answers

What is yellow nail syndrome, and what is it often a sign of?

Slowed or stopped nail growth, resulting in yellowish or greenish discoloration. Respiratory disease, such as chronic bronchitis. Signup and view all the answers

What is spoon nail, and what is it often a sign of?

A nail malformation where the outer surface of the nail is concave. Iron deficiency. Signup and view all the answers

What are Beau's lines, and what do they indicate?

Horizontal lines on the nail. Temporary interference with nail growth at the time the portion of the nail was formed. Signup and view all the answers

Why is the nail body darker in color, while the free edge of the nail is lighter?

The nail body has underlying capillaries, while the free edge does not. Signup and view all the answers

What is the lunula, and where is it located?

A whitish, semilunar area of the proximal end of the nail body. It has a lighter-colored appearance due to a thickened stratum basale. Signup and view all the answers

What is the eponychium, and where is it located?

A narrow band of epidermis extending from the margin of the nail wall onto the nail body. The cuticle. Signup and view all the answers

What is the primary function of the hair on the head?

Protection from sunburn and injury. Signup and view all the answers

What type of hair replaces lanugo hair at birth?

Vellus hair Signup and view all the answers

What is the role of the arrector pili?

To contract and pull on the hair follicle, producing goose bumps. Signup and view all the answers

What is the hair bulb composed of?

Epithelial cells Signup and view all the answers

What is the function of the hair matrix?

To produce keratin through a specialized type of keratinization. Signup and view all the answers

What is the outermost layer of the hair?

Cuticle Signup and view all the answers

What is the composition of the medulla?

Loosely arranged cells and air spaces, containing flexible, soft keratin. Signup and view all the answers

What are the two principal concentric layers of the hair follicle wall?

Outer connective tissue root sheath and inner epithelial tissue root sheath Signup and view all the answers

What is the significance of the dermal papillae?

They contain tiny blood vessels and nerves. Signup and view all the answers

At what stage of development does lanugo hair first appear?

In the last trimester of fetal development Signup and view all the answers

What is the primary function of hair within the nostrils?

To entrap particles and prevent their entry deeper into the respiratory system. Signup and view all the answers

What is the role of hair follicles in sensory reception?

Hair follicles have associated tactile receptors that detect light touch. Signup and view all the answers

What determines hair color?

Melanin synthesized in the matrix adjacent to the hair papillae. Signup and view all the answers

What is the longest phase of the hair growth cycle?

The anagen phase. Signup and view all the answers

What is the condition where the body mistakes selected hair follicles as foreign and attacks them?

Alopecia areata. Signup and view all the answers

What is the condition where hair is lost from the crown region of the scalp?

Male pattern baldness. Signup and view all the answers

What is the term for excessive hairiness in areas that normally do not have terminal hair?

Hirsutism. Signup and view all the answers

Why does hair become lighter in color as people age?

Due to the decrease in melanin production. Signup and view all the answers

What is the normal rate of hair loss per day?

Between 10 and 100 hairs per day. Signup and view all the answers

What is the function of eyelashes?

To protect the eyes. Signup and view all the answers

What is the primary cause of hirsutism?

An excess of male sex hormones, either through a medical condition or by certain medications. Signup and view all the answers

What are the two main types of exocrine glands found in the skin?

Sweat (sudoriferous) glands and sebaceous glands. Signup and view all the answers

What is the function of myoepithelial cells in sweat glands?

To contract and squeeze the gland to release its secretions. Signup and view all the answers

What is the main function of merocrine sweat glands?

Thermoregulation through evaporation of fluid from the skin. Signup and view all the answers

Where are apocrine sweat glands typically located?

In the axillae, around the nipples, in the pubic region, and in the anal region. Signup and view all the answers

What is the composition of sweat produced by merocrine sweat glands?

Approximately 99% water and 1% other chemicals, including electrolytes, metabolites, and waste products. Signup and view all the answers

What is the role of sweat gland secretions in protecting the skin?

They provide antibacterial and antifungal activity, dilute harmful chemicals, and prevent the growth of microorganisms. Signup and view all the answers

What would you expect to happen to sweat gland production and secretion when we are frightened or nervous?

An increase in sweat gland production and secretion. Signup and view all the answers

What is the significance of sebaceous glands in the skin?

They produce oily secretions that keep the skin and hair healthy. Signup and view all the answers

How do sweat glands respond to nervous system stimulation?

Myoepithelial cells contract, causing the sweat gland to discharge its accumulated secretions. Signup and view all the answers

How do cerumen and tiny hairs in the meatus work together to protect the eardrum?

Cerumen and tiny hairs in the meatus trap foreign particles or small insects, preventing them from reaching the eardrum. Signup and view all the answers

What is the main difference between mammary glands in males and females?

Mammary glands become functional only in pregnant and lactating females, producing breast milk to nourish offspring. Signup and view all the answers

How do apocrine sweat glands differ from merocrine sweat glands in terms of their secretions?

Apocrine sweat glands produce a protein-rich secretion, whereas merocrine sweat glands produce a watery secretion. Signup and view all the answers

What is the primary function of sebaceous glands, and where do they secrete their material?

Sebaceous glands secrete sebum, an oily substance, into hair follicles. Signup and view all the answers

What complex interaction controls the development of mammary glands and their secretions?

A complex interaction between gonadal and pituitary hormones controls the development of mammary glands and their secretions. Signup and view all the answers

What is the mechanism by which apocrine and merocrine sweat glands produce their secretion?

exocytosis Signup and view all the answers

What is the main difference between the secretions produced by apocrine and merocrine sweat glands?

viscous and cloudy with proteins and lipids, compared to watery and clear Signup and view all the answers

What is the function of sebum produced by sebaceous glands?

lubricant to keep skin and hair from becoming dry and brittle, and has some bactericidal properties Signup and view all the answers

What is the term used to describe plugged ducts of sebaceous glands?

acne Signup and view all the answers

What is the name of the glands located only in the external acoustic meatus that produce a waterproof earwax?

ceruminous glands Signup and view all the answers

What is the primary function of the mammary glands?

not mentioned in the text Signup and view all the answers

What is the usual time period when sebaceous glands become active and produce secretions?

puberty Signup and view all the answers

What is the main difference between an open comedo and a closed comedo?

appearance, with open comedo appearing blackish and closed comedo appearing whitish Signup and view all the answers

What is the term used to describe a large, fluid-filled nodule that can become severely inflamed and painful?

cyst Signup and view all the answers

What is the significance of hormones in stimulating sebaceous gland secretion?

hormones, especially male sex hormones, stimulate sebaceous gland secretion Signup and view all the answers

What are the three integumentary structures derived from the epidermis?

The three integumentary structures derived from the epidermis are nails, hair, and exocrine glands of the skin. Signup and view all the answers

What is the primary function of nails?

The primary function of nails is to protect the distal tips of the digits during jumping, kicking, or catching. Signup and view all the answers

What are the three parts that form the nail plate?

The three parts that form the nail plate are the distal light-colored free edge, the darker-colored nail body, and the nail root. Signup and view all the answers

What is the significance of changes in the shape, structure, or appearance of the nails?

Changes in the shape, structure, or appearance of the nails are clinically significant and can be indicative of a person's overall health. Signup and view all the answers

What causes brittle nails?

Overexposure to water or certain household chemicals can cause brittle nails. Signup and view all the answers

What is the composition of nails?

Nails are composed primarily of dead keratinocytes. Signup and view all the answers

During embryologic development, how do epidermal derivatives form?

During embryologic development, epidermal derivatives form as portions of the epidermis invaginate into the dermis. Signup and view all the answers

What is the nail bed?

The nail bed is a layer of epidermis that contains only the deeper, living cell layers of the epidermis. Signup and view all the answers

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

Merocrine sweat glands: the most numerous and widely distributed sweat glands, discharge their secretions directly onto the surface of the skin
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
Acne can occur at any age, but it is most prevalent during teenage years
There are different types of acne lesions, including comedos, papules, pustules, nodules, and cysts
Comedos can be open (blackheads) or closed (whiteheads) and are caused by plugged sebaceous glands
Papules are dome-shaped, fluid-filled lesions that can form red elevations on the skin
Pustules are similar to papules but are filled with a mixture of white blood cells, dead skin cells, and bacteria
Nodules are similar to pustules but extend deeper into the skin and can cause scarring
Cysts are large, fluid-filled nodules that can become severely inflamed and painful, leading to scarring
There are various medicinal treatments available for acne, including benzoyl peroxide, salicylic acid, antibiotics, and retinoids
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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Explore the process of wound healing and regeneration in the integumentary system, distinguishing between regeneration and fibrosis.