Chapter 6 Integumentary system part B mod (1)

Chapter 6: Integumentary System Part B

6.2a: Nails

• Function of Nails

  • Protect distal tips of digits.

  • Assist in grasping objects.

• Structures of the Nails:

  1. Nail Plate:

     • Comprises the nail body, nail root, and nail matrix.

  2. Nail Body:

     • Pinkish color due to underlying capillaries.

  3. Distal Free Edge:

     • Whitish area with no underlying capillaries.

  4. Nail Root:

     • Embedded part of the nail in the skin.

  5. Nail Bed:

     • Layer of living epidermis underneath the nail body.

  6. Nail Matrix:

     • Actively growing part located at the proximal end of the nail body.

  7. Lunula:

     • Whitish, semilunar area at the proximal end of the nail.

  8. Nail Folds:

     • Skin folds overlapping the nail.

  9. Eponychium (Cuticle):

     • Narrow band of epidermis from the nail wall to the nail body.

  10. Hyponychium:

  • Thickened stratum corneum beneath the free nail edge.

6.2b: Hair

• Overview:

  • Hair is found almost everywhere on the body and consists of keratinized cells forming slender filaments that grow from hair follicles.

• Types of Hair:

  1. Lanugo:

     • Fine, unpigmented downy hair; appears in the last trimester of pregnancy.

  2. Vellus:

     • Fine hair that covers most of the body; the primary human hair.

  3. Terminal Hair:

     • Coarse, pigmented, and longer hair found on the scalp, eyebrows, and eyelashes; also forms men's beards and replaces vellus hair in the axillary and pubic regions during puberty.

• Hair Components:

  1. Hair Matrix:

     • Structure at the base of the hair bulb where epithelial cells divide, producing new hair cells.

  2. Medulla:

     • Contains flexible, soft keratin; remnants of the hair matrix.

  3. Cortex:

     • Composed of hard, flattened cells.

  4. Cuticle:

     • A single layer of cells surrounding the cortex.

• Hair Follicle:

  • An oblique tube surrounding the hair root, extending into the dermis and possibly the subcutaneous layer.

  • Arrector Pili:

    • Smooth muscle that contracts to elevate hair, causing "goosebumps."

• Functions of Hair:

  • Protection from sunburn and injury (especially on the head).

  • Traps particles and debris in the respiratory system and ears.

  • Heat retention on the scalp.

  • Sensory reception through root hair plexuses.

  • Visual identification and social signaling.

• Hair Color and Growth Cycle:

  • Melanin synthesis in the hair matrix determines color.

  • As age increases, melanin production decreases, resulting in graying or whitening of hair.

  • Hair Growth Phases:

    1. Anagen: Active growth phase.

    2. Catagen: Regression phase with halted cell division.

    3. Telogen: Resting phase, where hair is shed.

• Hair Loss Conditions:

  • Alopecia Areata: Autoimmune disorder causing spots of baldness.

  • Diffuse Hair Loss: Shedding due to hormones, drugs, or deficiency.

  • Male Pattern Baldness: Genetic and hormonal loss in specific scalp areas.

6.2c: Exocrine Glands of the Skin

• Types of Exocrine Glands:

  1. Sudoriferous Glands:

     • Implicated in sweat production.

     • Two types:

       • Merocrine (Eccrine):

         • Most numerous, opening directly onto skin surface.

         • Composed mainly of water and electrolytes; essential for thermoregulation.

       • Apocrine:

         • Found in axillary and anogenital areas, producing thicker secretions that may result in body odor.

  2. Sebaceous Glands:

     • Holocrine glands producing oily sebum, lubricating skin and hair, also antibacterial.

• Other Glands:

  1. Ceruminous Glands:

     • Modified apocrine glands found in the external ear canal, producing cerumen (earwax).

  2. Mammary Glands:

     • Modified apocrine glands responsible for milk production in lactating females.

6.3: Repair and Regeneration of the Integumentary System

• Repair Mechanisms:

  • Regeneration: Marketed by the replacement of damaged cells with the same cell type, restoring function.

  • Fibrosis: Involves the formation of scar tissue, resulting in loss of original function.

• Stages of Wound Healing:

  • Involves multiple phases to repair tissue effectively.

Clinical View: Burns

• Types of Burns:

  1. First Degree Burns: Affect only the epidermis; present with redness and pain.

  2. Second Degree Burns: Involve epidermis and part of dermis; characterized by blisters and pain.

  3. Third Degree Burns: Affect all skin layers; require hospitalization and are generally not painful due to nerve damage; skin grafting is typically necessary.

• Burn Severity Evaluation:

  • The Rule of Nines method estimates burn area and fluid loss.

Skin Cancer

• Types of Skin Cancer:

  1. Basal Cell Carcinoma:

     • Least malignant, highly treatable through surgical excision.

  2. Squamous Cell Carcinoma:

     • Scaly, reddened lesions; can metastasize but has good prognosis with treatment.

  3. Melanoma:

     • Most dangerous, requiring early detection (ABCD rule) and aggressive treatment.

Hair Aging and Management

• Aging results in reduced stem cells, collagen, and elasticity, leading to wrinkles and thinner hair. Risk factors include UV exposure and smoking. Botox is a cosmetic treatment to reduce wrinkles by blocking muscle contractions.