Chapter 5 - Terms

List the overall functions of the integumentary system.

Protection/barrier (mechanical, chemicals, radiation, temperature, pathogens); thermoregulation; waste excretion; vitamin D production; sensory input

What does the integumentary barrier protect against?

Mechanical damage, chemicals, radiation, temperature extremes, pathogens

How does the integument help with thermoregulation?

Blood reservoir (5%); vasodilation/vasoconstriction; sweat glands

What is skin (the cutaneous membrane) and how thick is it?

Cutaneous membrane; 0.5 mm on eyelids to 4 mm on heels; mostly 1–2 mm elsewhere

What is the integument?

Skin + subcutaneous layer (hypodermis)

Epidermis: tissue type and blood supply

Keratinized stratified squamous epithelium; avascular

Stratum corneum

Surface layer of the epidermis; callus and dandruff

Stratum lucidum

Found in thick skin only

Stratum granulosum

Cells contain keratohyalin and lamellar granules

Stratum spinosum

Cells contain prekeratin filaments

Stratum basale

Deepest epidermal layer; mitotic stem cells and melanocytes

Dermis: blood supply and contents

Vascularized; accessory organs (glands, hair follicles, arrector pili muscles, nail roots)

Papillary region of the dermis

Top 1/5 of the dermis; areolar connective tissue

Reticular region of the dermis

Bottom 4/5 of the dermis; dense irregular connective tissue

Is the hypodermis (subcutaneous layer) a true layer of the skin?

Not a true layer of the skin

Tissues of the hypodermis

Adipose CT and areolar CT (contains Pacinian corpuscles)

Functions of the hypodermis

Support; binds dermis to underlying tissues; adipose storage; cushioning; insulation

Function of hairs (pili)

Protection; reduce heat loss; sense light touch

Function of the arrector pili muscle

Smooth muscle that causes goosebumps; aids thermoregulation

Function of the hair root plexus

Neuron dendrites wrap each hair follicle to detect hair movement

Overall functions of skin glands

Excretion; thermoregulation; secretion of sebum, sweat, and cerumen

Functions of nails

Grasp and manipulate objects; protect distal ends of digits; scratching; support and counter pressure to the palmar surface of the finger

Types of sensations detected by skin sensory receptors

Touch, pressure, temperature, tickle, itch, pain

Name the three types of skin glands

Sebaceous (oil); sudoriferous (sweat); ceruminous

Sebaceous glands: location and product

Typically connected to hair follicles; secrete sebum

Function of sebum

Prevents dehydration of hair and skin; inhibits growth of certain bacteria

Type of secretion used by sebaceous glands

Holocrine

Which gland type is associated with acne?

Sebaceous glands

Two types of sudoriferous (sweat) glands

Eccrine (merocrine) and apocrine

Ceruminous glands: product and secretion type

Cerumen; holocrine

Name the five sensory receptors of the integument

Hair root plexuses; Merkel's discs; free nerve endings; Meissner's corpuscles; Pacinian (lamellated) corpuscles

Hair root plexus: function and location

Senses hair movement; hair follicle (dendrites wrap each hair)

Merkel's discs: function and location

Sustained touch/pressure; stratum basale

Free nerve endings: function and location

Warmth, coolness, pain, tickling, itching; papillary/epidermal region

Meissner's corpuscles: function and location

Light touch and tickle; dermal papillae

Meissner's corpuscles are also called

Corpuscles of touch

Pacinian corpuscles: function and location

Deep pressure; deep reticular dermis or hypodermis

Pacinian corpuscles are also called

Lamellated corpuscles

Four cell types of the epidermis

Keratinocytes; melanocytes; macrophages (Langerhans cells); tactile epithelial cells (Merkel's discs)

Keratinocytes: percentage and function

90%; main structural cell of the epidermis

Melanocytes: percentage, function, location

1%; produce melanin for skin color and UV protection; stratum basale

Macrophages (Langerhans cells): percentage and function

8%; immune defense in the epidermis

Tactile epithelial cells (Merkel's discs): percentage and function

1%; sustained touch/pressure sensory receptors

Thin skin: epidermis thickness

75–150 μm

Thick skin: epidermis thickness

400–600 μm

Thin skin: stratum corneum and stratum lucidum

Thin corneum; no lucidum

Thick skin: stratum corneum and stratum lucidum

Thick corneum; has lucidum

Structures found in thin skin

Hair, sebaceous glands, and sweat glands

Structures found in thick skin

Many sweat glands; lacks hair and sebaceous glands

Where is thin skin found?

Everywhere there is a cutaneous membrane where thick skin is not present

Where is thick skin found?

Palms (palmar), soles (plantar), digits (volar surface)

Function of thick skin

Protection against friction and wear

Name the three pigments contributing to skin color

Melanin; carotene; hemoglobin

Melanin: color range and what it forms

Pale yellow to red to tan to black; accumulation causes freckles and moles

Carotene: color and location

Yellow to orange; concentrates in stratum corneum; most visible in palms and soles

Hemoglobin: color and what determines its effect

Red; dermal vascularization, vasoconstriction, and vasodilation

Hair shaft

Visible region above the skin surface

Hair root

Region below the skin surface, penetrating into the dermis/hypodermis

Hair bulb

Enlarged base at the bottom of the root

Hair follicle

Epithelial root sheath surrounded by a dermal root sheath

Hair accessory structures

Arrector pili muscle; hair root plexus; sebaceous glands

Eponychium (cuticle)

The stratum corneum of the epidermis

Nail matrix

Epithelium proximal to the nail root with dividing cells that produce new nail cells