Lecture 6 Slide Deck

Hemangiomas: Benign tumors of dermal blood capillaries, presenting as birthmarks.
- Strawberry birthmarks: Typically fade in childhood.
- Port wine birthmarks: Persist throughout life.
Freckles: Flat areas of increased melanin produced by melanized keratinocytes.
Moles (nevi): Elevated growths of melanized keratinocytes.
Friction Ridges: Unique patterns on fingers and toes, formed during fetal development.
- Unique patterns even among identical twins.
- Purpose: Sweat pores contribute to identifiable fingerprints.

Accessory Organ: Composed mainly of dead keratinized cells, with harder keratin than skin.
- Found universally across the body, with notable exceptions like palms and soles.
- Density: Similar across individuals, variation in pigmentation and texture.
- Vellus Hairs: Fine, pale, prevalent in children and biological females (65%).
- Terminal Hairs: Coarser, thicker, usually more prevalent in biological males (90%).

Protection and Insulation: Head hair protects against UV light and insulates the scalp.
Facial Recognition: Hair offers cues for individual identification.
Functionality:
- Eyebrows: Keep sweat out of eyes and aid in expressions.
- Eyelashes: Protect against debris and insects.
- Guard hairs: Protect nasal and ear canals.
- Pubic and axillary hair: Indicate sexual maturity and function in relation to sweat glands.

Parts of Hair:
- Bulb: Base of hair, originates in dermis or hypodermis; contains blood vessels and nerves (hair papilla).
- Root: Portion in the follicle.
- Shaft: Part extending above the epidermis.
Hair Layers:
- Medulla: Deepest layer, loosely packed cells with air spaces.
- Cortex: Thickest part composed of keratinocytes.
- Cuticle: Outer layer with shingle-like cells to anchor hair in follicle.

Hair follicles are tubes from which hair grows, derived from epidermal layers.
- Epithelial Root Sheath: Originates from epidermis, surrounds the hair root.
- Connective Tissue Root Sheath: Comes from dermis and surrounds the epithelial sheath.
- Arrector Pili Muscle: Smooth muscle associated with hair, causes "goose-bumps" when contracted due to stimuli.

Pigment Granules: Determine color in cortical cells.
- Eumelanin: Brown/black hair.
- Pheomelanin: Red hair, present in blonde as well.
- Air in Medulla: Leads to gray/white hair.
Texture: Cross-sectional shape includes:
- Round: Straight hair.
- Oval: Wavy hair.
- Flat: Curly hair.

Alopecia: General thinning or baldness, worsened by aging, stress, and poor nutrition.
- Pattern baldness influenced by genetics and testosterone.
Hirsutism: Excessive hairiness in females, often due to hormonal imbalance or menopause.

Composition: Produced from stratum corneum; consists of hard keratin.
Anatomy: Nail plate has free edge, body, and root, with the nail bed underneath.

Diagnostic Importance: Nails indicate overall health.
- Onychomycosis: Nail fungus leading to yellow nails.
- Spoon Nails: Concave nails indicating iron deficiency.
- Ingrown Nails: Nails growing into skin, often from improper trimming.

Types: Derive from epidermis, located primarily in the dermis.
- Sebaceous Glands: Secrete oil (sebum).
- Sudoriferous Glands: Sweat glands (eccrine and apocrine).
- Ceruminous Glands: Produce earwax.
- Mammary Glands: Modified sweat glands for milk production.

Secretion: Produce sebum; maintain hair/skin moisture.
- Ducts can open into hair follicles or the skin surface.
- Functions: Softens skin and hair, inhibits bacteria, increases during puberty.

Types: Eccrine and apocrine.
- Eccrine Glands: Widely distributed for thermoregulation; produce sweat with salts.
- Apocrine Glands: Located near hair follicles, may contribute to body odor.

Location: Found in the ear canal.
- Secretion Done: Combines with dead skin and oil to create earwax (cerumen).
- Functions: Waterproofs the canal, lubricates, protects from pests, and has antibacterial properties.

Developed from excess sun exposure, with melanocytes not providing full UV protection.
Types of Skin Cancer:
- Basal Cell Carcinomas: Least dangerous, shiny bumps.
- Squamous Cell Carcinomas: Originating from keratinocytes, more dangerous.
- Malignant Melanomas: High risk for metastasis, detected through unique ABCD signs (Asymmetry, Border irregularity, Color, Diameter).

Categorized by severity: first-degree (epidermis), second-degree (epidermis and part of dermis), third-degree (full-thickness).
Third-Degree Burns: Can be fatal due to infection and fluid loss.

Tool for estimating burn extent by dividing body into 11 regions, each accounting for 9% of body surface area.

Used for treatment of full-thickness burns, types include:
- Autograft: Self-donated skin.
- Allograft: Skin from another person.
- Xenograft: Skin from another organism.

Dermatology: Study of skin disorders.
- Vitiligo: Autoimmune skin condition resulting in white patches.
- Blisters: Fluid-filled separations between epidermis and dermis.
- Striae: Stretch marks due to collagen tearing, common on specific body areas.
- Acne: Inflammation and blockage of sebaceous glands; can lead to whiteheads, blackheads, and pus formation.