Integumentary System Quiz

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Questions and Answers

Which layer of the skin is composed of stratified squamous epithelium?

Subcutaneous layer

Hypodermis

Epidermis (correct)

Dermis

What is the primary function of keratin in the skin?

Sensation

Physical protection (correct)

Water retention

Vitamin D synthesis

Which statement about thick skin is correct?

It is predominantly found on the eyelids.

It contains hair follicles and sebaceous glands.

It is thinner than thin skin.

It has a thick stratum corneum. (correct)

What substance is produced by epidermal cells in response to UV radiation?

Cholecalciferol Signup and view all the answers

Which function of the skin involves changing blood flow to regulate body temperature?

Thermoregulation Signup and view all the answers

Which of the following components is NOT part of the integumentary system?

Cartilage Signup and view all the answers

What type of connective tissue primarily composes the dermis?

Dense irregular connective tissue Signup and view all the answers

Which characteristic distinguishes thick skin from thin skin?

Absence of hair follicles Signup and view all the answers

What is the primary barrier function of the skin against UV radiation?

Keratin production Signup and view all the answers

Which function of the skin includes the presence of various nerve endings?

Sensation Signup and view all the answers

What is the primary function of keratinocytes in the epidermis?

Producing keratin Signup and view all the answers

Which layer of the epidermis contains melanocytes that synthesize melanin?

Stratum basale Signup and view all the answers

What characteristic distinguishes the stratum lucidum from other epidermal layers?

Is only present in thick skin Signup and view all the answers

What happens to keratinocytes as they migrate towards the skin surface?

They flatten and accumulate keratin Signup and view all the answers

Which type of cell in the epidermis is primarily responsible for touch sensation?

Tactile cells Signup and view all the answers

What occurs during vasoconstriction in response to cold temperatures?

Blood vessels constrict to retain core body heat Signup and view all the answers

What is the primary component of the dermis that helps prevent overstretching?

Collagen fibers Signup and view all the answers

Which layer of the dermis provides mobility for leukocytes?

Papillary layer Signup and view all the answers

What causes the formation of calluses on the skin?

Accumulation of dead keratinocytes due to repeated friction Signup and view all the answers

What is the main function of the epidermal water barrier?

Preventing water loss Signup and view all the answers

What is the role of dendritic cells in the epidermis?

Engage in immune defense Signup and view all the answers

What structural feature enhances the connection between the dermis and epidermis?

Dermal papillae Signup and view all the answers

How long does it typically take for a keratinocyte to make its way to the skin surface?

30 to 40 days Signup and view all the answers

What type of tissue is mainly responsible for the production of blood cells in red bone marrow?

Hematopoietic tissue Signup and view all the answers

What primarily causes dermatitis?

Infection and mechanical irritation Signup and view all the answers

Which bone type is primarily affected when bone resorption exceeds bone formation?

Spongy bone Signup and view all the answers

Which type of melanin is responsible for brown and black skin tones?

Eumelanin Signup and view all the answers

What substance does yellow bone marrow primarily consist of?

Adipose tissue Signup and view all the answers

What is a characteristic finding of vitiligo?

Patchy loss of skin color Signup and view all the answers

What process is responsible for the hardening of bone through the deposition of calcium salts?

Calcification Signup and view all the answers

What function do friction ridges serve on the skin?

Enhance grip and sensitivity Signup and view all the answers

At what age does human bone growth typically stop?

25 years Signup and view all the answers

What primarily composes hair and nails?

Dead keratinized cells Signup and view all the answers

In which bones is red bone marrow predominantly found in adults?

Skull and vertebrae Signup and view all the answers

Which of the following statements is TRUE about bone remodeling?

Homeostasis requires a balance between osteoblast and osteoclast activity. Signup and view all the answers

What is the role of the hypodermis?

Connect skin to underlying tissues and store fat Signup and view all the answers

Which factor can lead to an increase in bone production?

Increased gravity Signup and view all the answers

Which gland produces a milky sweat containing fatty acids?

Apocrine sweat glands Signup and view all the answers

What is the main cause of decubitus ulcers?

Compression of superficial blood vessels Signup and view all the answers

What happens to hair when it is exposed to cold temperatures?

The arrector pili muscle contracts Signup and view all the answers

Which skin condition is characterized by yellowing due to bilirubin in the blood?

Jaundice Signup and view all the answers

Which type of hair is fine and unpigmented, present on a fetus?

Lanugo Signup and view all the answers

What is a common characteristic of nails that can indicate medical issues?

Color changes and swelling Signup and view all the answers

Which hair component is responsible for pigmentation?

Cortex Signup and view all the answers

What type of perspiration is characterized by moisture that is not noticed and does not produce visible wetness?

Insensible perspiration Signup and view all the answers

Which glands are responsible for producing sebum to keep the skin and hair moist?

Sebaceous glands Signup and view all the answers

What is the primary function of cerumen produced by ceruminous glands?

To waterproof the ear canal Signup and view all the answers

Which growth factor is essential for promoting the division of germinative cells and stimulates epidermal repair?

Epidermal growth factor Signup and view all the answers

What is the ABCDE rule used for?

To detect signs of skin cancer Signup and view all the answers

Which type of burn involves only the epidermis and typically heals within days?

First-degree burn Signup and view all the answers

What is the significance of the mammary ridges or milk lines in most mammals?

They suggest milk-producing potential Signup and view all the answers

What kind of burn is characterized by blistering and can take weeks to several months to heal?

Second-degree burn Signup and view all the answers

Which of the following best describes a third-degree burn?

Involves all layers of the skin and possibly deeper tissues Signup and view all the answers

Which type of skin lesion typically appears as a raised, reddened, scaly area that can develop a concave ulcer?

Squamous cell carcinoma Signup and view all the answers

Which type of skin cancer is considered the least dangerous due to its low chance of metastasis?

Basal cell carcinoma Signup and view all the answers

What is the main function of the skeletal system in terms of movement?

To facilitate limb movement and breathing Signup and view all the answers

Which term describes the process by which bone tissue becomes hardened?

Both B and C Signup and view all the answers

Which medical procedure is often necessary for treating third-degree burns?

Skin grafting Signup and view all the answers

Study Notes

Introduction

The integumentary system is the largest and most vulnerable organ.
Its primary function is to protect the body from external threats like radiation, trauma, infection, and chemicals.
The skin requires tactics to repair itself due to its exposure to these threats.
Dermatology is the scientific study and medical treatment of the integumentary system (skin).

The Skin and Subcutaneous Tissue

The integumentary system consists of the cutaneous membrane (skin) and accessory structures (hair, glands, nails).
The skin (integument) is comprised of two layers:
- Epidermis: The outer layer composed of stratified squamous epithelium.
- Dermis: The deeper layer composed of dense connective tissue.
- Hypodermis (superficial fascia/subcutaneous layer): Not part of the skin, but usually studied with it.
The skin's thickness ranges from 0.5 to 6 mm, varying mainly due to dermis thickness.
- 0.5 mm: Eyebrows, allowing for quick movement.
- 6 mm: Back, shoulder blades, scapula.
Skin classification is based on epidermis:
- Thick skin: Covers palms, soles, fingers, and toes, containing only sweat glands and no hair follicles or sebaceous glands.
- Thin skin: Covers the rest of the body, containing hair follicles, sebaceous glands, and sweat glands.

Functions of the Skin

Protection: Resistance to trauma and infection.
- Keratin: Provides physical protection, linking cells together.
- Dermcidin, defensin, and acid mantle: Protect against bacteria.
Vitamin D synthesis: UV radiation converts cholecalciferol (vitamin D3) into calcitriol by the liver and kidneys.
Sensation: Many nerve endings detect various stimuli, including touch and temperature.
Thermoregulation: Alters blood flow to regulate body temperature.
- Cutaneous vasodilation: Dilates blood vessels, releasing heat.
- Cutaneous vasoconstriction: Constricts blood vessels, retaining heat.
Nonverbal communication: Facial expressions like eyebrow raises, frowns, and smiles.

Epidermis

Keratinized stratified squamous epithelium: Dead cells at the surface packed with keratin protein.
Avascular: Lacks blood vessels, relying on diffusion of nutrients from the dermis.
Sparse nerve endings for touch and pain.

Cells of the Epidermis

Keratinocytes: The majority of epidermal cells, synthesize keratin for skin strength.
Stem cells: Found in the stratum basale, undifferentiated cells that give rise to keratinocytes.
Melanocytes: Synthesize melanin, which absorbs ultraviolet radiation to protect DNA.
Tactile cells: Touch receptor cells associated with dermal nerve fibers, located in the stratum basale.
Dendritic cells: Phagocytic immune cells guarding against toxins and microbes, found in the stratum spinosum and stratum granulosum.

Layers of the Epidermis

Stratum basale (stratum germinativum): Single layer of stem cells and keratinocytes resting on the basement membrane, also containing melanocytes and tactile cells.
Stratum spinosum: Several layers of living keratinocytes joined by desmosomes and tight junctions, containing dendritic cells.
Stratum granulosum: Three to five layers of flat, living keratinocytes that begin to dehydrate and die, containing keratohyalin granules.
Stratum lucidum: Thin, pale layer found only in thick skin, containing keratinocytes packed with clear protein eleidin, cells are dead and lack nucleus/organelles.
Stratum corneum: Up to 30 layers of dead, scaly, keratinized cells, resisting abrasion, penetration, and water loss.

The Life History of a Keratinocyte

Keratinocytes are produced by mitosis in the stratum basale or stratum spinosum.
New keratinocytes push older ones towards the surface (stratum corneum).
Over time, keratinocytes flatten, producing more keratin and lipid-filled lamellar granules.
After 30 to 40 days, a keratinocyte reaches the skin surface and exfoliates as dander.
Epidermal water barrier: Located in the stratum granulosum, it is formed by lipids from keratinocytes and tight junctions.

The Dermis

Connective tissue layer, 0.2 to 4 mm thick.
Composed mainly of collagen and elastic fibers, providing strength and flexibility.
Well-supplied with blood vessels, sweat glands, sebaceous glands, and nerve endings.
Houses hair follicles and nail roots.
Muscles of facial expression attach to the dermis.
Wavy, bumpy boundary with the epidermis, increasing surface area and strength of connection.
- Dermal papillae: Upward finger-like extensions of the dermis.
- Epidermal ridges: Downward waves of epidermis.

Papillary Layer

Superior layer of areolar tissue.
Promotes mobility of leukocytes and other defense cells.
Rich in small blood vessels.

Reticular Layer

Deeper, thicker layer of dense irregular connective tissue.
Enables stretching in all directions.
Stretch marks (striae): Tears in collagen fibers due to stretching.
Blisters: Formation of serous fluid between dermis and epidermis due to damaged dermal blood vessels.

Fibers in the Dermis

Collagen fibers: Strong, resist overstretching, and allow flexibility.
Elastic fibers: Permit stretching and recoiling to original length, providing flexibility.
Skin turgor: Caused by water content in the skin, allowing it to snap back to shape.
- Dehydrated skin loses turgor, exhibiting wrinkles (pinched skin stays pinched).

Skin Layers & Color

Dermatitis: Inflammation of the papillary layer, causing pain, itching, and rapid spread across the skin. Can be caused by infection, radiation, or irritation from mechanical or chemical sources.
Decubitus Ulcers (Bedsore): Occur due to impaired dermal circulation, often from compression of superficial blood vessels. Commonly found on skin covering joints or bony prominences, leading to cell death and tissue erosion.
Melanin: Pigment responsible for skin and hair color, produced in melanocytes and stored in melanosomes. Melanosomes are transferred to keratinocytes, clustering around the nucleus to absorb UV radiation, which can damage DNA.
- Eumelanin: Brown and black varieties, contributing to tan, brown, and black skin tones.
- Pheomelanin: Yellowish to reddish tones in certain Asian and Native American populations, and pinkish tones in white skin.
Other Factors Influencing Skin Color:
- UV Radiation: Stimulates melanin synthesis, leading to increased melanocytes during tanning.
- Dermal Vessels & Collagen: Degree of visibility of these structures influences skin tone.
- Diet: Carotene pigment from yellow and orange vegetables can accumulate in the epidermis and dermis, contributing to skin color. Carotene is used to produce vitamin A, crucial for epithelial maintenance and visual pigment. Vitamin A deficiency can cause night blindness (nyctalopia).

Diagnostic Skin Colors

Cyanosis: Bluish skin coloration resulting from oxygen deficiency in blood.
Erythema: Redness due to increased blood flow to the skin.
Pallor: Paleness caused by decreased blood flow to the skin.
Albinism: White skin resulting from a genetic lack of melanin, affecting skin, hair, and even eyes.
Vitiligo: Patches of skin color loss due to melanocyte destruction, possibly caused by an autoimmune reaction.
Jaundice: Yellowing of the skin due to bilirubin accumulation in the blood, a byproduct of hemoglobin breakdown. Can be caused by liver dysfunction, impairing bilirubin filtration.
Hematoma: Bruising, resulting from blood clotting under the skin.

Skin Markings

Friction Ridges: Formed by dermal papillae, creating unique fingerprint patterns on fingertips. Enhance fingertip sensitivity and improve grip.
Flexion Lines (Flexion Creases): Lines on flexor surfaces of joints (digits, palms, wrists, elbows). Mark sites where skin folds during joint flexion.
Freckle: Flat, melanized patch of skin.
Mole (Nevus): Elevated, melanized patch, often with hair. Should be monitored for color, diameter, or contour changes, potentially signifying cancer.
Hemangiomas (Birthmarks): Discolored skin patches caused by benign overgrowth of dermal capillaries. Some disappear in childhood, while others persist.
- Capillary Hemangioma: Strawberry birthmark.
- Cavernous Hemangioma:
- Port-wine Stain:

The Hypodermis

Hypodermis (Subcutaneous Tissue): Connective tissue layer beneath the skin, containing more areolar and adipose tissue than the dermis. Serves as body padding, binding skin to underlying tissues.
Subcutaneous Fat: Adipose tissue component of the hypodermis, acting as an energy reservoir and providing thermal insulation.
- Thicker: Females
- Thinner: Infants and elderly
- Common Drug Injection Site: Due to abundant blood vessels.

Hair & Nails: Accessory Organs

Hair & Nails: Composed primarily of dead, keratinized cells.
- Soft Keratin: Found in the stratum corneum of skin.
- Hard Keratin: Makes up hair and nails, tougher and more compact due to disulfide bridges between keratin molecules.

Hair: Structure and Functions

Hair (Pilus): Slender filament of keratinized cells growing from a hair follicle. Covers most of the body, except palms, soles, lips, nipples, and parts of genitals.
- Limbs & Trunk: 55-70 hairs per square cm.
- Face: About 10 times as many hairs per square cm.
- Scalp: Approximately 100,000 hairs, with hair loss occurring with age.
Hairiness Variation: Primarily due to differences in hair texture and pigment.
Types of Hair:
- Downy Hair (Lanugo): Fine, unpigmented hair present on the fetus in the last three months of development.
- Vellus Hair: Fine, pale hair that replaces lanugo at birth. Makes up two-thirds of female hair, one-tenth of male hair, and all hair of children except eyebrows, eyelashes, and scalp hair.
- Terminal Hair: Longer, coarser, pigmented hair. Includes eyebrows, eyelashes, scalp hair, axillary and pubic hair after puberty, male facial hair, and some trunk and limb hair.
Hair Structure:
- Shaft: Portion above the skin surface.
- Root: Portion below the skin surface.
- Bulb: Dilated hair root end in the dermis or hypodermis.
  - Dermal Papilla: Bud of vascular connective tissue, providing nutrition to the hair.
  - Hair Matrix: Mitotically active cells above the papilla, responsible for hair growth.
- Hair Layers:
  - Medulla: Loosely arranged cells and air spaces at the core.
  - Cortex: Main bulk of hair; layers of elongated cells.
  - Cuticle: Outermost layer of overlapping, thin, scaly cells.
Hair Follicle Layers:
- (External & Internal) Epithelial Root Sheath: Extension of the epidermis adjacent to the hair root, widening at the deep end into the bulge, a source of stem cells for follicle growth.
- Connective Tissue Root Sheath: Denser layer derived from the dermis, surrounding the epithelial root sheaf.
Hair Follicle Associations:
- Sensory Nerve Fibers: Entwine each follicle, responding to hair movements.
- (Piloc) Arrector Muscle: Smooth muscle attaching follicle to dermis, contracting to cause piloerection (hair standing on end).

Hair Texture & Color

Hair Color: Determined by pigment granules in cortex cells.
- Brown & Black Hair: Rich in eumelanin.
- Red Hair: High concentration of pheomelanin.
- Blond Hair: Moderate pheomelanin and very little eumelanin.
- Gray & White Hair: Little or no melanin, with air present in the medulla.
Hair Texture: Related to hair cross-sectional shape.
- Straight Hair: Round.
- Wavy Hair: Oval.
- Curly Hair: Relatively flat.

Nails

Fingernails & Toenails: Clear, hard derivatives of stratum corneum composed of dead cells, packed with hard keratin.
- Hard Keratin: Stronger than hair, due to more disulfide bridges.
Nail Functions:
- Grooming: Picking apart food, other manipulations.
- Sensitivity: Provides counterforce to enhance fingertip sensitivity to tiny objects.
Nail Structure:
- Nail Plate: Hard part of the nail, including free edge, nail body, and nail root.
- Nail Fold: Surrounding skin rising on the sides, separated from the nail plate by the nail groove.
- Nail Bed: Skin underneath the nail plate.
- Nail Matrix: Growth zone at the proximal end of the nail, obscuring underlying vessels and appearing as the white lunule.
- Cuticle (Eponychium): Zone of dead skin overhanging the proximal end of the nail.
Nail Appearance in Diagnosis:
- Swollen, Clubbed Fingertips: Oxygen deficiency.
- Dietary Deficiencies:

Cutaneous Glands

Sweat Glands: Exocrine glands, producing sweat.
- Apocrine Sweat Glands: Found in groin, anal region, axilla, areola, and beard area in males. Ducts lead to nearby hair follicles, producing milky sweat containing fatty acids. Become active at puberty, responding to stress and sexual stimulation.
  - Bromhidrosis: Disagreeable body odor, often from inadequate hygiene, as bacteria utilize fatty acids for energy.
- Eccrine (Merocrine) Sweat Glands: Most numerous skin glands, dense on palms, soles, and forehead. Produce watery perspiration for body cooling.
  - Myoepithelial Cells: Present in both apocrine and eccrine glands, contracting in response to sympathetic nervous system stimulation to squeeze perspiration up the duct.
Sweat Production & Composition:
- 99% Water:
- pH Range: 4 to 6, forming an acid mantle that inhibits bacterial growth.
- Filtration: Begins as a protein-free filtrate of blood plasma, produced by the deep secretory portion of the gland, and oozes out of capillaries.
- Reabsorption: Some sodium chloride is reabsorbed by the duct, but some remains along with other small solutes (potassium, urea, lactic acid, ammonia).
- Drug Excretion: Some drugs are excreted in sweat.

Perspiration

Insensible perspiration
- Not noticeable
- Does not produce visible wetness of skin
- Lose approximately 500 mL/day
- Cutaneous transpiration: water loss from skin not due to sweating
  - Water diffuses between the keratinocytes and evaporates from the skin surface
  - Skin is not completely waterproof, loses water & can gain water
Diaphoresis: sensible perspiration; sweating with wetness of the skin
- In response to heat, exercise, circulatory shock
- 1 L or more of sweat per hour may be lost during exercise

Sebaceous Glands

Produce oily secretion called sebum
Gland structure: flask-shaped, short ducts open into hair follicles
Holocrine mode of secretion: fill, burst, & die; then coats hair follicle
Keeps skin and hair from becoming dry, brittle, and cracked

Ceruminous Glands

Modified apocrine glands found only in external ear canal
- Coiled, simple tubular glands
- Produce cerumen (earwax)
  - Yellow, waxy secretion combined with sebum and death epithelial cells; waterproofs the canal
  - Keeps eardrum pliable
  - Kills bacteria
  - Makes guard hairs of ear sticky to help block foreign particles from entering auditory canal

Mammary Glands

Milk-producing glands that develop in female during pregnancy & lactation
- Modified apocrine sweat glands, produce casein
- Rich secretion released through mammary ducts opening at nipple
- Mammary ridges or milk lines: two rows of mammary glands in most mammals
  - Primates kept only two glands, but a few people have additional nipples along the milk line (polythelia)

Skin Disorders

Skin Cancer

Most skin cancer is caused by exposure to UV rays of the sun
Most often on the head, neck, and hands
Most common in fair-skinned (little melanin) people and the elderly
One of the most common, easily treated cancers
Highest survival rates if detected and treated early

Types of Skin Cancer

Basal cell carcinoma: most common type; least dangerous because it seldom metastasizes; forms from cells in stratum basale; small, shiny bump with central depression and beaded edges
Squamous cell carcinoma: arises from keratinocytes of stratum spinosum; lesions usually on scalp, ears, lower lip, or back of the hand; raised, reddened, scaly appearance later forming a concave ulcer; chance of recovery good with early detection and removal; tends to metastasize to lymph nodes and may become lethal
Melanoma: arises from melanocytes; less than 5% of skin cancers; can be successfully removed if caught early, but usually fatal if metastasizes; greater risk factor is familial history; highest incidence in males, redheads, people who had severe sunburn as a child; ABCDE rule for detecting melanoma:
- A: asymmetry (in shape)
- B: border irregularity
- C: color (mix of brown, black, tan, red/blue)
- D: diameter (greater than 6 mm)
- E: evolving (size, shape, color)

Burns

Burns can result in death due to fluid loss, infection, and toxic effects of eschar – the burned, dead tissue
Classified according to depth of tissue involvement:
- First-degree burn: only involves the epidermis; redness, slight edema, and pain; heals within days
- Second-degree burn (partial-thickness burn): involves part of dermis; may appear red, tan, or white; blistered and painful; two weeks to several months to heal and may leave scars
- Third-degree burn (full thickness burn): involves all of dermis and often some deeper tissues; often requires skin grafts; need fluid replacement, infection control, supplemental nutrition; may damage pain receptors so it may hurt less than second-degree or first

Skin Grafts

Third-degree burns often require skin grafts
- Autograft: tissue from another location on the same person’s body
- Allograft: tissue from unrelated person, usually deceased donors
- Artificial and lab-based approaches under development
Epidermal growth factor: peptide growth factor that
- Promote division of germinative cells
- Accelerates keratin production
- Stimulates epidermal repair
- Stimulates glandular secretions

Bone Development

Human bones grow until approximately the age of 25
Ossification or osteogenesis: the formation of bone
Calcification: the process of depositing calcium salts during bone ossification and in other tissues (ex. teeth)

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Test your knowledge on the integumentary system with this quiz. You will answer questions about skin layers, functions, and characteristics, focusing on the epidermis and dermis. Perfect for students studying biology or anatomy.