Integumentary System Quiz

Integumentary System Overview

• The skin, also known as the integument, comprises about 16% of total body weight.
• Its surface area is approximately 1.5-2.0 square meters.
• It's constantly being worn away.
• It's composed of two main parts: the cutaneous membrane and accessory structures.

Functions of the Integument

• Protects underlying tissues and organs from impacts, abrasions, fluid loss, and chemical attacks.
• Excretes salts, water, and organic wastes via integumentary glands.
• Maintains body temperature.
• Produces melanin, protecting underlying tissues from UV radiation.
• Produces keratin, protecting against abrasion and acting as a water repellent.
• Synthesizes vitamin D3.
• Stores lipids in adipocytes.
• Detects sensations like touch, pressure, and pain.

Layers of Skin

• Epidermis: Composed of closely packed epithelial cells.
• Dermis: Made of dense irregular connective tissue, housing blood vessels, hair follicles, sweat glands, and other structures.
• Hypodermis: Below the dermis, mainly composed of loose connective and fatty tissues.

Epidermis Strata

• The epidermis consists of keratinocytes arranged in strata.
• Thin skin has 4 strata layers.
• Thick skin (palms and soles) has 5 strata layers.

Strata (Layers) of the Epidermis

• Stratum Corneum (Horny Layer): Outermost layer, 15-30 layers of dead keratinized cells held together by desmosomes. Slightly water resistant.
• Stratum Lucidum (Clear Layer): Only found in thick skin. Flattened, keratin-filled cells.
• Stratum Granulosum (Grainy Layer): 3-5 layers of keratinocytes that produce keratin, and change to become less permeable. Includes keratohyalin and lipid granules.
• Stratum Spinosum (Spiny Layer): 8-10 layers of keratinocytes bound together by desmosomes. Contains Langerhans cells (important for the immune system).
• Stratum Basale (Basement Layer): Innermost layer, attached to the basement membrane. Basal cells (stem cells) divide to replace superficial keratinocytes. Melanocytes (pigment-producing cells) and Merkel cells (touch receptors) are also found here.

Ridges of the Skin

• Epidermal ridges form fingerprints and help hold the dermis and epidermis together.
• Dermal papillae, projections from the dermis, interlock with the epidermal ridges.

Dermis

• The dermis supports and connects the epidermis and hypodermis to the rest of the body.
• Papillary Layer: Made of areolar tissue, containing blood vessels nourishing the epidermis and sensory receptors.
• Reticular Layer: Dense irregular connective tissue containing blood vessels, nerve fibers, and accessory organs (hair follicles, sweat glands).

Hypodermis

• Separates the skin from deeper structures.
• Functions in stabilizing skin position relative to underlying tissues, allowing for independent movement.
• Primarily composed of adipose tissue, which is important for energy storage.

Pigmentation

• Skin color is influenced by epidermal pigmentation (melanin and carotene) and dermal circulation.

Accessory Organs of Skin

• Hair Follicles: Produce hairs for protection.
• Hair Shafts and Arrector Pili Muscles: Generate goosebumps and assist in thermoregulation.
• Exocrine Glands: Assist in thermoregulation and excrete wastes, including sweat glands and sebaceous glands.
• Nails: Protect and support fingertips and toes, derivative of stratum corneum (made of hard keratin).

Acne

• Results from over-productive sebaceous glands.
• Plugged follicles lead to blackheads and skin inflammation.

Burns

• Classified by the depth of tissue damage: first-degree (epidermis only), second-degree (epidermis and part of dermis), and third-degree (entire thickness).
• Significant consequences include fluid/electrolyte imbalance, impaired thermoregulation, and increased risk of infection (sepsis).

Age-Related Skin Changes

• Reduced melanocyte activity, drier epidermis, and thinner epidermis are common changes.
• Impaired immune response, decreased perspiration and skin repair and decreased blood supply are also seen.

Skin Cancer

• Basal cell carcinoma: Most common type, originating from stratum basale. Virtually no metastasis, high survival rate.
• Squamous cell carcinoma: Second most common, affecting keratinocytes. May appear as lesions, and high risk of metastasis.
• Malignant melanoma: Most serious type, originating from melanocytes. High risk of metastasis, and reduced survival rate if detected later. ABCDE rule for diagnosis (Asymmetry, Border irregularity, Color variation, Diameter changes, Evolution).