Integumentary System Quiz

Integumentary System Overview

• The integumentary system consists of skin and its derivatives (nails, hair, sweat glands, sebaceous glands).
• The integument is the skin that covers the body.
• Also known as the cutaneous membrane.
• Acts as a barrier to the outside world.
• Visually indicates physiology and health.
• Dermatological study and treatment.

Key Terms

• Derm/o = skin
• Sub = under, below
• Epi = above
• Lip/o = fat
• Cutane/o = skin
• Py/o = pus
• Melan/o = black

Properties of the Integument

• Body's largest organ.
• Protects internal body structures.
• Accounts for 7-8% of body weight.
• Area ranges between 1.5-2.0 square meters.
• Thickness ranges between 1.5 mm and 4.0 mm.
• A postage-stamp-sized sample of skin contains:
  • ~ 280 cm of blood vessels
  • ~ 220 cm of nerves
  • ~ 60 oil glands
  • ~ 900 sensory receptors (10,000 on finger tips).
  • ~ 2 million cells.

Composition of the Integument

• Composed of all tissue types.
• Surface covered by an epithelium.
• Underlying connective tissue:
  • Provides strength and resilience.
  • Contains smooth muscle associated with hair follicles.
• Nervous tissue:
  • Provides information on touch, pressure, temperature, and pain.

Layers of the Integument

• Epidermis:
  • Stratified squamous epithelium.
• Dermis:
  • Deeper layer.
  • Primarily dense irregular connective tissue.
• Subcutaneous Layer:
  • Deep to the dermis.
  • Layer of alveolar and connective tissue.
  • Also called hypodermis.
  • Not part of the integumentary system but closely involved with its structure and function.

Composition of the Integument: Epidermis

• The epithelium of the integument is termed epidermis.
• Keratinized, stratified squamous epithelium.
• Consists of specific layers (strata):
  • Stratum corneum
  • Stratum lucidum
  • Stratum granulosum
  • Stratum spinosum
  • Stratum basale

Stratum basale

• Also known as stratum germinativum or basal layer.
• Contains three cell types:
  • Keratinocytes (basal):
    • Most abundant in epidermis, found in all layers.
    • Dividing to regenerate new cells.
  • Melanocytes:
    • Scattered among keratinocytes.
    • Produce and store melanin in response to UV light.
  • Tactile cells (few, AKA Merkel cells):
    • Sensitive to touch.
    • Release chemicals to stimulate sensory nerve endings when compressed.

Stratum spinosum

• Also known as the spiny layer.
• Contains keratinocytes.
• Epidermal dendritic cells (Langerhans cells):
  • Often present in stratum spinosum and stratum granulosum.
  • Immune cells that help initiate the immune response.
  • Responsive to pathogens and epidermal cancer cells.

Stratum granulosum

• Also known as the granular layer.
• First layer of keratinization.
  • Keratinocytes fill with keratin.
  • Nucleus and organelles disintegrate.
  • Fully keratinized cell, structurally sound but process incomplete until more superficial layers.

Stratum lucidum

• Only in thick skin.
• Translucent layer (also known as the clear layer).
• Filled with a translucent protein, eleidin.
• Intermediate product in keratin maturation.
• Cells are dead.

Stratum corneum

• Also known as the hornlike layer.
• Anucleate.
• Surface unsuitable for growth, secretions of exocrine glands also helping prevent growth.
• Cells are dead.

Migration of Keratinocytes

• Originate from stem cells in stratum basale.
• Migrate through strata to stratum corneum over approximately two weeks.
• Undergo structural changes.
• Remaining in stratum corneum for another two weeks before being shed.

Thick Skin vs. Thin Skin

• Thick skin:
  • Located on the palms of hands, soles of feet, and surfaces of fingers and toes.
  • Contains all five layers of epidermal strata.
  • Has sweat glands, lacks hair follicles and sebaceous glands
  • 0.4-0.6 mm thick.
• Thin skin:
  • Covers most of the body.
  • Lacks a stratum lucidum.
  • Has sweat glands, hair follicles, and sebaceous glands.
  • 0.075-0.150 mm thick.

Composition of the Integument: Dermis

• Dermis:
  • Deep to the epidermis.
  • 0.5-3 mm thick.
  • Composed of connecive tissue.

Components of the Dermis

• Primarily collagen with elastic and reticular fibers.
• Motile dendritic cells for immune function.
• Blood vessels, sweat glands, sebaceous glands, hair follicles, nail roots, sensory nerve endings, arrector pili.
• Divided between papillary layer and deeper reticular layer.

Papillary Layer of the Dermis

• Superficial region of the dermis.
• Directly adjacent to the epidermis.
• Composed of areolar connective tissue.
• Derives name from projections termed dermal papillae.
• Contain capillaries, sensory nerve endings.
• Projections of epidermis interdigitate with papillae, termed epidermal ridges.
• Interlock to increase contact area between layers.

Reticular Layer of the Dermis

• Deeper, major portion of the dermis.
• Extends from papillary layer to subcutaneous layer.
• Primarily dense irregular connective tissue.
• Contains large bundles of collage fibers, interwoven into a meshwork surrounding structures in dermis.

Lines of Cleavage, Stretch Marks and Wrinkles

• Collagen and elastic fibers are oriented in parallel bundles aligned as the result of applied stress during routine movement.
• Orientation indicated by lines of cleavage (tension lines).
• Important consideration for surgery. Surgical incisions parallel to these lines are more likely to heal quickly; perpendicular incisions more likely to open due to cut elastic fibers.
• Stretch marks occur when skin is stretched beyond its capabilities; some collagen fibers torn.
• Flexibility and thickness diminished by UV light and aging.
• Aging can cause sagging or wrinkled skin.

Innervation and Blood Supply of Dermis

• Extensive nerve fibers in dermis: -Sensory nerve fibers detect pressure, vibration, and cold. -Motor nerve fibers control blood flow and gland secretions.
• Dermal blood vessels supply nutrients to epidermis and dermis, important in thermoregulation.

Vasoconstriction and Vasodilation

• Vasoconstriction:
  • Blood vessel diameters narrow.
  • Blood shunted from periphery to deeper structures.
  • Occurs when trying to conserve heat.
  • Pale skin when exposed to cold.
• Vasodilation:
  • Blood vessel diameters increase.
  • More blood close to body surface.
  • Occurs when body needs to lose heat.
  • Flushed skin during exercise.

Clinical View: Tattoos

• Permanent images produced on integument.
• Dye injected into dermis.
• Becomes permanent part of the dermis layer.
• Usually impossible to completely remove a tattoo.

Composition of the Integument: Subcutaneous Layer

• Not considered part of the integument.
• Composed of areolar and adipose connective tissue.
• Termed subcutaneous fat in areas of lots of adipose.
• Connective tissue fibers interwoven with those of the reticular dermis.
• Pads and protects the body.

Functions of the Integument

• Protection:
  • Acts as a physical barrier.
  • Protects the body from physical injury and trauma, chemicals, toxins, microbes, temperature extremes.
  • Protects deeper tissues from solar radiation.
• Prevention of water loss:
  • Helps prevent unnecessary water loss.
  • Water unable to exit the skin unless secreted by sweat glands.
  • Dehydration, a danger with severe burns.
• Water resistant but not waterproof.
• Metabolic regulation:
  • Skin able to convert some compounds to slightly different forms.
  • UV rays stimulate melanocytes to produce melanin.
• Secretion and absorption:
  • Waste products (urea, salts, water) secreted onto surface during sweating (amounts adjusted for electrolyte homeostasis).
  • Sebum from sebaceous glands lubricates skin surface and hair. -Can absorb certain chemicals and drugs (some other materials are blocked—selectively permeable).
  • Oil-soluble drugs can be absorbed via transdermal administration to get continued, slow absorption of drug over a long period.
• Immune function:
  • Dendritic cells (in stratum spinosum) initiate immune response against pathogens and attack cancer cells. Also present in dermis.
• Temperature regulation:
  • Influenced by capillaries and sweat glands.
  • Blood vessel dilation and sweating when body too warm.
  • Blood vessel constriction when body too cold.
• Sensory reception:
  • Detects heat, cold, touch, pressure, and vibration (mostly in dermis).
  • Some shared functions with epidermis (e.g., secretion, absorption, and immune function).

Repair and Regeneration

• Response to repetitive mechanical stress:

  • Mitosis stimulated in stratum basale.
  • Epidermis thickens (e.g., thickened soles after walking barefoot).

• Response to damaged tissue:

  • Cells with the same type replace damaged cells to restore organ function.
  • Gap filled with scar tissue (fibrosis).
  • Composed of collagen, produced by fibroblasts.
  • Functional activities of tissues not restored if organ too damaged or the cells lack the ability to divide.

• Stages of wound healing:

  1. Cut blood vessels bleed into wound
  2. Blood clot forms, leukocytes clean wound. (Clot is temporary barrier).
  3. Blood vessels regrow, granulation tissue forms (vascular connective tissue is initially formed in wound)
  4. Epithelium regenerates, connective tissue fibrosis occurs.

• Wound Healing: Not rapid. Longer for wider, deeper wounds, less likely to return to original condition (hair follicles, exc. glands, nerves, and arrector pili muscle not repaired).

Test your knowledge on the integumentary system with this quiz covering topics such as skin pigments, layers of the skin, and factors affecting skin color. Ideal for students studying biology or health sciences, this quiz will challenge your understanding of skin anatomy and its functions.