Integumentary System Overview Quiz

Integumentary System Overview

• The integumentary system is made up of skin and its appendages.
• Skin is the largest organ in the body, composed of various tissues.
• Dermatology is the medical specialty that diagnoses and treats skin disorders.

Functions of Skin

• Protection: Cushions, insulates, waterproofs, and protects against chemicals, heat, cold, and bacteria; screens UV rays.
• Synthesizes vitamin D: with UV rays.
• Regulates body temperature: Vasodilation (increases blood flow) and vasoconstriction (decreases blood flow) control body temperature through sweat evaporation.
• Prevents water loss: Skin prevents the loss of unnecessary water through its protective barrier.
• Sensory reception: Nerve endings and receptor cells detect temperature, pain, pressure, and touch.
• Excretion: Sweat removes water, salt, uric acid, and ammonia from the body.
• Blood reservoir: The dermis contains an extensive network of blood vessels, carrying 8-10% of the total blood flow in a resting adult.

Types of Skin

• Most of the body is comprised of thin skin.
• Thick skin is nonhairy and found on the palms of the hands and soles of feet.
• The difference in skin types is due to differences in the thickness of the epidermis.
• Skin layers include the epidermis and dermis.

Epidermis

• The epidermis is stratified squamous keratinized epithelium.
• Contains keratinocytes, special cells like melanocytes (make skin pigment melanin), Merkel cells (associated with sensory nerve endings), and Langerhans cells (macrophage-like dendritic cells).
• Layers of epidermis (from deep to superficial): stratum basale/germinativum, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

Dermis

• A strong, flexible connective tissue layer with fibroblasts, macrophages, mast cells, and WBCs.
• Contains collagen, elastic, and reticular fibers.
• Critical for temperature regulation (through blood vessels).
• Contains sweat glands (in thick and thin skin), sebaceous glands, hair follicles, and arrector pili muscles.
• Two layers—papillary and reticular layers.

Stratum Basale

• The deepest layer of epidermis, containing a single layer of columnar or cuboidal keratinocytes resting on the basement membrane.
• Cells divide, pushing older cells upward and eventually die.
• Melanocytes and Merkel cells are found here.

Stratum Spinosum

• Contains 8-10 layers of polyhedral cells (with many sides).
• Cells are often separated by narrow, translucent clefts, having spine-like cytoplasmic extensions connected by desmosomes.
• Produces cytokeratin, also contains Langerhans cells.

Stratum Granulosum

• The cells become flat (3 to 5 layers).
• Accumulates many large, basophilic keratohyaline granules as the cells mature and begin to die.

Stratum Lucidum

• Consists of several layers of clear, flat dead cells with faint nuclear outlines.
• Keratinocytes lack distinct boundaries, filled with intermediate protein eleidin.
• Present only in thick skin

Stratum Corneum

• The outermost layer, composed of keratinized cells (filled with keratin).
• Approximately 30 cells thick.
• Nuclei are not visible; cells are very flat.
• The space between cells is filled with lipids that cement the cells to form a continuous membrane.

Hair

• Absent in some areas (palms, soles, etc.)
• Shaft (superficial), root (below surface in the dermis), composed of three layers (medulla, cortex, and cuticle) with keratin and pigments.

Hair Follicle

• Tube that houses the hair root.
• Dilates at its base to form the hair bulb containing blood capillaries.
• Arrector pili muscle associated with the follicle.

Sebaceous Glands

• Found in the dermis of thin skin, opening into the upper portion of hair follicles.
• Produce sebum by holocrine secretion (entire secreting cell forms part of the secretion).
• Oily secretion lubricates and protects the hair and skin.

Sweat Glands

• Found throughout the skin surface (except nipples and external genitalia).
• Prevent overheating by producing sweat, which is mostly water.
• Two types: Eccrine and Apocrine.

Eccrine Glands

• Mostly numerous; true sweat; open through pores; 99 % water and some salts.

Apocrine Glands

• Axillary, anal, and genital areas; ducts open into hair follicles; organic molecules that decompose with time with an odor.

Modified Apocrine Glands

• Ceruminous (earwax)
• Mammary (milk)

Burns

• Injury to skin or other tissues primarily caused by heat, radiation, electricity, friction, or chemicals.
• Classified as first-degree (superficial), second-degree (partial-thickness), third-degree (full-thickness), and fourth-degree (full-thickness).

Rule of Nines

• Used to estimate the extent of burn injuries, dividing the body into percentages of total body surface area (TBSA).
• Important for initial management of burn patients and calculating fluid replacement needs according to the Parkland Formula.