Skin Anatomy and Hair & Nail Structure

Skin Anatomy

• The skin is composed of three main layers:
  • Epidermis: outermost layer, thin, and avascular
  • Dermis: middle layer, thicker, and vascular
  • Hypodermis: innermost layer, composed of adipose tissue
• Skin appendages:
  • Hair follicles
  • Sebaceous glands
  • Sweat glands
  • Nails

Hair And Nail Structure

• Hair:
  • Composed of keratin, a protein
  • Has a root, shaft, and follicle
  • Growth rate: 0.3-0.4 mm/day
• Nail:
  • Composed of keratin and dead cells
  • Has a nail plate, nail bed, and nail matrix
  • Growth rate: 0.1-0.2 mm/day

Sweat And Sebaceous Glands

• Sweat glands:
  • Produce sweat, a clear, watery fluid
  • Two types: eccrine and apocrine
  • Eccrine glands: found all over the body, produce sweat in response to heat and stress
  • Apocrine glands: found in armpits and groin, produce sweat in response to emotional stress
• Sebaceous glands:
  • Produce sebum, an oily substance
  • Found in the dermis, associated with hair follicles
  • Help to moisturize the skin and hair

Skin Disorders

• Common skin disorders:
  • Acne: caused by clogged pores and bacterial infection
  • Eczema: caused by inflammation and dry skin
  • Psoriasis: caused by rapid skin cell growth
  • Skin cancer: caused by UV radiation and genetic mutations

Wound Healing

• Stages of wound healing:
  1. Inflammation: blood clot forms, and immune cells respond to injury
  2. Debridement: dead tissue is removed
  3. Proliferation: new tissue is generated
  4. Remodeling: new tissue is strengthened
• Factors that affect wound healing:
  • Age
  • Nutrition
  • Infection
  • Diabetes

FUNCTIONS OF THE SKIN

• Protection:
  • Barrier against external factors (e.g. temperature, UV radiation)
  • Prevents water loss
• Regulation:
  • Thermoregulation: helps to regulate body temperature
  • Blood pressure regulation: helps to regulate blood pressure
• Sensation:
  • Detects sensations such as touch, pressure, and temperature
• Excretion:
  • Removes waste products through sweat
• Production:
  • Produces vitamin D upon UV radiation exposure

Skin Anatomy

• The skin is composed of three main layers: epidermis, dermis, and hypodermis
• Epidermis is the outermost layer, thin, and avascular
• Dermis is the middle layer, thicker, and vascular
• Hypodermis is the innermost layer, composed of adipose tissue

Skin Appendages

• Skin appendages include hair follicles, sebaceous glands, sweat glands, and nails

Hair Structure

• Hair is composed of keratin, a protein
• Hair has a root, shaft, and follicle
• Hair growth rate is 0.3-0.4 mm/day

Nail Structure

• Nails are composed of keratin and dead cells
• Nail has a nail plate, nail bed, and nail matrix
• Nail growth rate is 0.1-0.2 mm/day

Sweat Glands

• Sweat glands produce sweat, a clear, watery fluid
• There are two types of sweat glands: eccrine and apocrine
• Eccrine glands are found all over the body, produce sweat in response to heat and stress
• Apocrine glands are found in armpits and groin, produce sweat in response to emotional stress

Sebaceous Glands

• Sebaceous glands produce sebum, an oily substance
• Found in the dermis, associated with hair follicles
• Help to moisturize the skin and hair

Skin Disorders

• Acne is caused by clogged pores and bacterial infection
• Eczema is caused by inflammation and dry skin
• Psoriasis is caused by rapid skin cell growth
• Skin cancer is caused by UV radiation and genetic mutations

Wound Healing

• Stages of wound healing: inflammation, debridement, proliferation, and remodeling
• Factors that affect wound healing: age, nutrition, infection, and diabetes

Functions of the Skin

• Protection: barrier against external factors, prevents water loss
• Regulation: thermoregulation, blood pressure regulation
• Sensation: detects sensations such as touch, pressure, and temperature
• Excretion: removes waste products through sweat
• Production: produces vitamin D upon UV radiation exposure