Marieb Human Anatomy & Physiology Twelfth Edition Chapter 05: The Integumentary System

Flashcards covering key concepts from Chapter 5, The Integumentary System, including skin layers, cell types, functions, appendages, and clinical considerations such as skin cancer and burns.

What components make up the integumentary system?

The integumentary system consists of the skin, sudoriferous (sweat) glands, sebaceous (oil) glands, hairs, nails, and subcutaneous tissue.

What are the two distinct layers of the skin?

The two distinct layers of the skin are the epidermis and the dermis.

Describe the epidermis.

The epidermis is the outermost protective shield of the body, consisting of epithelial tissue and is avascular.

Describe the dermis.

The dermis underlies the epidermis, makes up the bulk of the skin, consists mostly of dense connective tissue, and is vascular.

What is the subcutaneous tissue, and what are its functions?

Also called the hypodermis or superficial fascia, it is not part of the skin but shares functions. It consists mostly of adipose tissue with some areolar connective tissue and functions to loosely anchor the skin to underlying structures, provide shock absorption, and insulation.

What are the four main cell types found in the epidermis?

The four main cell types of the epidermis are keratinocytes, melanocytes, dendritic cells, and tactile epithelial cells.

What is the primary function of keratinocytes?

Keratinocytes produce fibrous keratin, a protein that provides the skin's protective properties.

What is the role of melanocytes in the epidermis?

Melanocytes are spider-shaped cells in the deepest epidermis(Basal Layer) that produce melanin, which protects keratinocyte nuclei from UV damage.

What is the function of dendritic cells (Langerhans cells) in the epidermis?

Dendritic cells are star-shaped macrophages that patrol the deep epidermis, ingest foreign substances, and are key activators of the immune system.

What are tactile epithelial cells (Merkel cells) and where are they located?

Tactile epithelial cells are sensory receptors for touch, located at the epidermal-dermal junction.

List the five layers of the epidermis from deepest to most superficial, including the optional layer.

The five layers of the epidermis are: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only in thick skin), and stratum corneum.

Which epidermal layer is responsible for active cell division?

The stratum basale (basal layer), also known as stratum germinativum, consists of a single row of actively dividing stem cells.

In which epidermal layer do keratinization begin and cells accumulate keratohyaline and lamellar granules?

Keratinization begins in the stratum granulosum, where cells accumulate keratohyaline granules (to form keratin) and lamellar granules (water-resistant glycolipid).

Which epidermal layer is only found in thick skin?

The stratum lucidum is a thin, translucent band found only in thick skin, superficial to the stratum granulosum.

What are the main functions of the stratum corneum?

Though dead, the stratum corneum protects deeper cells from the environment, prevents water loss, protects from abrasion and penetration, and acts as a barrier against biological, chemical, and physical assaults.

What are the two layers of the dermis?

The two layers of the dermis are the papillary dermis and the reticular dermis.

What are 'dermal papillae' and what do they contain?

Dermal papillae are superficial regions of the dermis that send finger-like projections into the epidermis. They contain capillary loops, free nerve endings (pain receptors), and touch receptors (tactile corpuscles).

What forms friction ridges in thick skin and what are their functions?

Friction ridges are formed by dermal papillae on top of dermal ridges, giving rise to epidermal ridges. They enhance gripping ability and contribute to the sense of touch by enhancing vibrations.

What are 'cleavage (tension) lines' and why are they important to surgeons?

Cleavage lines are caused by many collagen fibers running parallel to the skin surface in the reticular layer. Incisions made parallel to these lines heal more readily.

What are 'striae'?

Striae, or 'stretch marks,' are silvery white scars caused by extreme stretching of the skin that results in dermal tears.

What happens when acute, short-term trauma such as a burn or repeated friction occurs to the skin?

Acute, short-term traumas to the skin can cause blisters, which are fluid-filled pockets that separate the epidermal and dermal layers.

What are the three pigments that contribute to skin color?

The three pigments that contribute to skin color are melanin, carotene, and hemoglobin.

How does melanin influence skin color and what is its primary function?

Melanin is the only pigment made in the skin by melanocytes; its amount and form determine skin color differences. Its primary function is to shield the DNA of keratinocytes from damaging UV sunlight.

What is carotene and where does it accumulate in the skin?

Carotene is a yellow to orange pigment, most obvious in the palms and soles, and it accumulates in the stratum corneum and subcutaneous tissue.

What causes the pinkish hue of fair skin?

The pinkish hue of fair skin is due to lower levels of melanin, allowing the color of hemoglobin in dermal capillaries to show through.

What medical condition is indicated by 'cyanosis'?

Cyanosis, or blueness, indicates low oxygenation of hemoglobin, often a sign of respiratory or cardiovascular issues.

What condition might 'jaundice' indicate?

Jaundice, or yellowness of the skin, can indicate liver disorders.

List three functions of hair.

Hair senses insects on the skin, guards against physical trauma, protects from heat loss, and shields skin from sunlight.

What are the two main regions of a hair?

The two main regions of a hair are the root (portion within the scalp) and the shaft (portion extending above the scalp).

What is the 'arrector pili' muscle and what does it do?

The arrector pili is a small band of smooth muscle attached to the hair follicle, responsible for causing 'goose bumps'.

What are the two types of hair found on the body?

The two types of hair are vellus hair (pale, fine body hair) and terminal hair (coarse, long hair found on the scalp, eyebrows, and adult pubic/axillary regions).

What is 'hirsutism'?

Hirsutism is a condition in which females develop coarse, terminal hair in a masculine distribution, often due to an excess of androgens.

What structure is responsible for nail growth?

The nail matrix, a thickened portion of the nail bed, is responsible for nail growth.

What is 'koilonychia' and what can it signify?

Koilonychia, or 'spoon nail,' is an outward concavity of the nail that may signal iron deficiency.

What are the two main types of sweat glands?

The two main types of sweat glands are eccrine (merocrine) sweat glands and apocrine sweat glands.

Describe eccrine sweat glands and their primary function.

Eccrine sweat glands are the most numerous type, abundant on palms, soles, and forehead. They function in thermoregulation by secreting hypotonic sweat (99% water, salts, wastes, dermcidin) onto the skin surface.

Where are apocrine sweat glands primarily located and when do they begin functioning?

Apocrine sweat glands are mostly located in the axillary and anogenital areas, beginning to function at puberty. Their function is unknown but may act as sexual scent glands.

Name two types of modified apocrine sweat glands and their secretions.

Ceruminous glands secrete cerumen (earwax), and mammary glands secrete milk.

What do sebaceous glands secrete and what are its properties?

Sebaceous glands secrete sebum, an oily secretion with bactericidal properties that softens hair and skin.

What is 'acne'?

Acne is an infectious inflammation of the sebaceous glands, resulting in pimples (pustules or cysts), often associated with Propionibacterium acne bacteria.

List the six main functions of the skin.

The main functions of the skin include protection, body temperature regulation, cutaneous sensations, metabolic functions, blood reservoir, and excretion.

Name the three types of protective barriers the skin provides.

The skin provides chemical barriers, physical barriers, and biological barriers.

How does the skin regulate body temperature in a hot environment?

In a hot environment, the skin dilates dermal vessels and increases sweat gland activity to produce noticeable sweat (sensible perspiration) to cool the body.

What are 'exteroreceptors' in the skin?

Exteroreceptors are cutaneous sensory receptors that respond to stimuli outside the body, such as touch, deep pressure, hair movement, and painful stimuli.

What metabolic function does the skin perform related to Vitamin D?

The skin can synthesize Vitamin D, which is needed for calcium absorption in the intestine.

What percentage of the body's total blood volume can the skin hold?

The skin can hold up to 5% of the body's total blood volume, acting as a blood reservoir.

What are the two most damaging skin disorders beyond common infections?

Beyond common infections, the most damaging skin disorders are skin cancer and burns.

What are the three major types of skin cancer?

The three major types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma.

Which type of skin cancer is the least malignant and most common?

Basal cell carcinoma is the least malignant and most common, accounting for 80% of skin cancer cases.

Why is melanoma considered the most dangerous type of skin cancer?

Melanoma is the most dangerous type because it is highly metastatic (spreads quickly) and resistant to chemotherapy.

What is the 'ABCD rule' used for in recognizing skin cancer?

The ABCD rule is a mnemonic for recognizing signs of melanoma: Asymmetry, Border irregularity, Color (multiple), and Diameter (>6 mm).

What is the immediate threat to life from severe burns?

The immediate threat from severe burns is dehydration and electrolyte imbalance, which can lead to renal shutdown and circulatory shock.

How is the 'rule of nines' used in evaluating burns?

The rule of nines divides the body into 11 sections, each representing 9% of body surface area (except genitals at 1%), to estimate the volume of fluid loss.

Distinguish between first-degree, second-degree, and third-degree burns.

First-degree burns only damage the epidermis (redness, edema, pain). Second-degree burns damage the epidermis and upper dermis (blisters). Third-degree burns involve the entire thickness of the skin (gray-white, cherry red, or blackened; nerve endings destroyed; requires grafting).

What is 'lanugo coat' in fetal development?

The lanugo coat is a delicate, colorless hair covering the fetus during the 5th and 6th months, which is shed in the 7th month.

What is 'vernix caseosa' and its function in a fetus?

Vernix caseosa is a white, cheesy substance produced by sebaceous glands that protects the skin of the fetus while in the watery amniotic fluid.

How do epidermal replacement, subcutaneous fat, and elasticity change with aging skin?

With aging, epidermal replacement slows (skin becomes thin, dry, itchy), and subcutaneous fat and elasticity decrease (leading to cold intolerance and wrinkles).

What is the function of desmosomes?

Skin anchoring

Keratinocytes die when they migrate away from their source of nutrients in the underlying dermis. Above which layer of the epidermis are keratinocytes too far from the dermal capillaries to survive?  

Stratum granulosum

Match the following skin layer with its description: Stratum spinosum.

Several cell layers thick, with intermediate filaments, keratinocytes and dendritic (Langerhans) cells

Match the following structure with its primary tissue type: Reticular dermis.

Dense irregular connective tissue

Match the following term with its associated skin condition: Jaundice.

Yellowish coloring of skin caused by an accumulation of the pigment bilirubin

Touch receptors called tactile (Meissner’s) corpuscles are found in which region?

Papillary dermis

Match the following structure with its primary tissue type: Papillary dermis.

Areolar connective tissue

What cells would be expected to be found in the dermis?.

Fibroblasts, macrophages, and mast cells are typically found in the dermis, supporting skin structure and immune response.

Match each of the following hair-associated structures with its description: Hair follicle receptor (root hair plexus)

A knot of sensory nerve endings wrapped around the base of a hair follicle

Match each of the following hair-associated structures with its description: Hair bulb

The expanded, deep region of a hair follicle

Match each of the following hair-associated structures with its description: Cortex

Middle layer of hair that consists of several layers of flattened cells

Match each of the following hair-associated structures with its description: Medulla

Innermost layer of hair that consists of large cells and air spaces

Match each of the following hair-associated structures with its description: Hair matrix

Actively dividing cellular area of the bulb that produces the hair

Match each of the following hair-associated structures with its description: Cuticle

Outer layer of hair that consists of a single layer of cells overlapping one another

Select the cutaneous sensory receptors responsible for detecting bumps or contacts involving deep pressure.

Lamellar (Pacinian) corpuscles