Theme 6: Thermoregulation, Burns & Wound Healing

Cutaneous vasodilation

Widening of skin blood vessels that increases heat transfer from the body to the environment.

Cutaneous vasoconstriction

Narrowing of skin blood vessels that reduces heat loss.

Evaporative cooling

Heat is removed when sweat evaporates from the skin.

How do vasodilation and sweating cool the body together?

More warm blood reaches the skin while sweat evaporation removes heat.

First-degree burn

Superficial burn involving the epidermis.

Second-degree burn

Partial-thickness burn involving the epidermis and part of the dermis; often very painful.

Third-degree burn

Full-thickness burn destroying the epidermis and dermis; may extend into hypodermis.

Why can a full-thickness burn center be painless?

Destruction of sensory nerve endings can eliminate pain sensation in the center.

Why are partial-thickness burns often very painful?

Sensory nerve endings remain exposed or irritated in the damaged dermis.

Structures damaged in a deep full-thickness burn

Epidermis, dermis, sensory receptors, blood vessels, glands, follicles, and possibly hypodermis.

Hemostasis in wound healing

Initial clot formation helps stop bleeding after tissue injury.

Inflammatory phase

Immune cells remove debris and pathogens; inflammatory cells migrate into the wound.

Proliferative phase

Fibroblasts deposit collagen and new capillaries grow, forming granulation tissue.

Maturation/remodeling phase

Collagen is reorganized and strengthened; epithelial repair and scar remodeling continue.

Granulation tissue

New connective tissue rich in capillaries that fills a healing wound.

Macrophages in wound healing

Phagocytose debris and help coordinate repair.

Fibroblasts in wound healing

Produce collagen and other extracellular matrix components.

Deep wound-healing sequence

Hemostasis/clot formation → inflammation → proliferation/granulation tissue → maturation/remodeling.

Epidermal stem cells

Cells in the basal layer that divide to replace epidermal cells during repair.

Scar formation

Repair tissue remains after deeper injury; it may not fully restore the original tissue architecture.