Integumentary System Overview Quiz

Integumentary System

• The integumentary system includes skin, hair, nails, subcutaneous tissue, and various glands.
• Skin is composed of the epidermis (outer layer), dermis (inner layer), and hypodermis (subcutaneous layer).

Skin Functions

• Protection from injury
• Protection against infection
• Regulates body temperature
• Regulates water loss
• Chemical synthesis
• Sensory perception

Types of Membranes

• Mucous Membranes line cavities and tubes that open to the outside.
• Serous Membranes line body cavities with no outside opening. They secrete serous fluid.
• Cutaneous Membrane (skin) is the outer covering of the body.
• Synovial Membranes line joint cavities and secrete synovial fluid.

Skin Layers and Attachment Layer

• Epidermis: covers the internal and external surfaces of the body.
• Dermis: inner layer containing accessory skin structures (hair follicles, sweat glands)
• Hypodermis/subcutaneous layer: attaches skin to underlying organs and tissues.

Thin Skin vs. Thick Skin

• Thin skin: 1-2 mm thick, covers most of the body (except palms and soles), contains hair follicles.
• Thick skin: up to 6 mm thick, found on palms and soles, no hair follicles.

Epidermal Cell Types

• Keratinocytes: 90% of epidermal cells, produce keratin (fibrous protein), protecting and waterproofing the skin.
• Langerhans Cells: help with immune responses, from bone marrow.
• Melanocytes: produce melanin, contribute to skin color, and absorb UV light.
• Merkel Cells: least numerous epidermal cells, in the deepest epidermis; along with tactile discs, function in sensation of touch.

Epidermal Layers

• Stratum Corneum: outermost layer of dead, keratinized cells.
• Stratum Lucidum: only found in thick skin (palms and soles), layer of clear, flat, dead keratinocytes.
• Stratum Granulosum: cells begin to keratinize and produce a lipid-rich secretion.
• Stratum Spinosum: contains 8-10 layers of keratinocytes.
• Stratum Basale: deepest layer, new cells are formed.

Growth of Epidermis

• Newly formed cells in the stratum basale undergo keratinization as they move to the surface.
• Cells accumulate more keratin, then undergo apoptosis (programmed cell death).
• Eventually, cells slough off and are replaced. This process takes about 4 weeks.
• The rate of cell division in the stratum basale increases during injury.

Dermis

• Second deepest layer of skin.
• Composed mainly of connective tissue (collagen and elastic fibers).
• Papillary layer: surface area increased by projections (dermal papillae), contains capillaries for blood supply, and tactile receptors.
• Reticular layer: contains hair follicles, nerves, sebaceous glands, and sudoriferous glands.

Hypodermis

• Attaches skin to underlying organs and tissues.
• Not part of the skin. Contains connective tissue and adipose tissue (subcutaneous fat) providing insulation.
• Infants and elderly have less subcutaneous fat compared to adults. This sensitivity to cold.

Skin Color

• Genetic factors: melanin production regulated by genes.
• Environmental factors: exposure to sunlight.
• Volume of blood: hemoglobin present in blood modifies skin color.

Skin Pigments

• Melanin: predominantly located in the epidermis. Two forms (eumelanin-brownish black, pheomelanin-reddish yellow).
• Dark-skinned people have more eumelanin than light-skinned people.
• Carotene: yellow-orange pigment, precursor to vitamin A, found in stratum corneum and fatty areas of dermis & hypodermis.
• Hemoglobin: oxygen-carrying pigment in blood cells.

Environmental Factors Affecting Melanin Production

• UV light: increases enzyme activity in melanocytes leading to increased melanin production.
• Increased melanin protects from UV radiation.
• Too much UV light causes skin cancer.

Skin Markings

• Friction ridges: markings on fingertips (fingerprints); crucial for object manipulation.
• Flexion lines: found in joints (elbows and wrists); tight skin attachment.
• Freckles: flat melanized patches.
• Moles: elevated melanized skin patches.

Aging Skin

• Stem cell activity declines.
• Increased difficulty in repair.
• Reduced immune response, vitamin D3 production declines, etc.
• Blood supply to dermis decreases.
• Hair follicles die or produce thinner hair.
• Skin becomes less elastic.

Skin Derivatives

• Thousands of epidermal cells from the stratum basale migrate into the dermis during embryonic development. This forms hair follicles and glands.

Hair and Nails

• Hair: protects scalp from injury/sunlight, protects the eyes, assists in sensing touch.
• Hair Anatomy: shaft (projects from skin), root (penetrates dermis), medulla, cortex, cuticle, hair follicle, bulb, papilla, matrix, arrector pili.
• Hair Features & Texture: variety of shapes, sizes, and colors; affect the way hair looks and feels.
• Hair Growth: Anagen (growth), Catagen (transitional), and Telogen (resting) phases.
• Nails: composed of tightly packed, keratinized epidermal cells; protection, object manipulation, securing nail to fingertip.

Skin Glands

• Sudoriferous Glands: eccrine & apocrine sweat glands.
• Sebaceous Glands: produce oil.
• Ceruminous Glands: modify sweat to produce ear wax.

Skin Receptors

• Sensitive to pressure, heat, cold, pain.
• Free nerve endings for touch, pressure, and pain.

Skin Imbalances

• Skin lesions: injuries/infections.
• Skin infections: viral (cold sores, herpes), bacterial (boils, carbuncles, impetigo), fungal (athlete's foot).
• Contact dermatitis: irritant (soaps, detergents), allergic (poison ivy, nickel).

Genetic Disorders

• Psoriasis: chronic, noninfectious skin disease, with skin dryness and scaling, pustules.
• Vitiligo: autoimmune disorder where melanocytes are destroyed, resulting in patches of skin loss of pigment.

Skin Cancer

• Very common.
• ABCD: Asymmetry, Border irregularity, Color variation, Diameter.
• Prevention: SPF 15, hats, shirts with sleeves, sunglasses, avoid tanning beds.
• Types: melanoma, basal cell carcinoma, squamous cell carcinoma.

Test your knowledge on the integumentary system, including the structure and functions of skin, hair, nails, and various membranes. This quiz covers key concepts such as the layers of skin, types of membranes, and the essential roles of the integumentary system in maintaining homeostasis.