Wound Healing and Skin Repair - Anatomy and Physiology
- Which vitamin is required to hydroxylate proline and lysine during collagen synthesis?
- Vitamin C (ascorbic acid). Deficiency produces weak collagen and poor wound healing.
- Which skin structures are absent from scar tissue?
- Hair follicles, sebaceous glands and sweat glands, because dense collagen replaces the original dermis.
- In a partial-thickness wound, where can new epidermis arise besides the wound edges?
- From epithelial cells lining surviving hair follicles and sweat glands in the dermis.
- Which cells pull wound edges together during wound contraction?
- Myofibroblasts, fibroblasts that contain contractile actin filaments.
- What is healing by secondary intention?
- Healing of an open wound that fills with granulation tissue and closes by contraction, leaving a larger scar.
- A clean surgical incision is closed with sutures. By which type of healing will it repair?
- Primary intention, because the wound edges are approximated.
- How do glucocorticoid drugs affect wound healing?
- They delay it, by suppressing inflammation and reducing fibroblast collagen synthesis.
- How does a keloid differ from a hypertrophic scar?
- A keloid grows beyond the borders of the original wound; a hypertrophic scar stays within them.
- About what fraction of normal skin's tensile strength does a mature scar reach?
- About 70 to 80 percent, even after months of remodeling.
- What is healing by primary intention?
- Healing of a clean wound whose edges are brought together, as with sutures, producing minimal granulation tissue and a thin scar.
- An abrasion removes only the epidermis. How does it heal, and does it scar?
- By re-epithelialization from basal keratinocytes at the wound edges; it typically heals without a scar.