JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Pharmacy I Year PATHOPHYSIOLOGY Previous Question Paper (September/October-2021 - R17)

Nuclear damage is a hallmark of irreversible cell injury, often preceding cell death (necrosis or apoptosis). It manifests through three primary morphological changes: pyknosis, karyorrhexis, and karyolysis.

1. Pyknosis: The nucleus undergoes shrinkage and becomes a small, dense, deeply basophilic mass of condensed chromatin.
2. Karyorrhexis: The pyknotic nucleus undergoes fragmentation into smaller, irregular pieces, resulting in nuclear debris scattered within the cytoplasm.
3. Karyolysis: The chromatin fades due to the action of DNAases and RNAases, leading to the complete dissolution of the nucleus, leaving only a faint, ghost-like outline.

These processes are driven by the activation of endogenous enzymes, particularly endonucleases, which degrade nuclear DNA, leading to the loss of genetic integrity and functional failure of the cell.

Wound healing is a complex, dynamic biological process aimed at restoring tissue integrity after injury. It occurs through three overlapping phases: inflammation, proliferation, and remodeling.

1. Inflammatory Phase: Triggered immediately after injury, this phase involves hemostasis (platelet plug formation) and the recruitment of neutrophils and macrophages to the site. These cells clear debris, bacteria, and damaged tissue through phagocytosis and release growth factors to initiate repair.
2. Proliferative Phase: This phase focuses on filling the wound gap. Fibroblasts migrate to the site and synthesize collagen and extracellular matrix components, while angiogenesis (formation of new blood vessels) ensures oxygen and nutrient supply. Epithelial cells migrate to cover the wound surface, forming granulation tissue.
3. Remodeling Phase: This is the final and longest phase, where the initial disorganized collagen (Type III) is replaced by stronger, more organized collagen (Type I). The wound contracts, and the vascularity decreases, resulting in the formation of a mature scar with increased tensile strength.

Healing occurs via primary intention (clean, approximated edges, minimal scarring) or secondary intention (large wounds, significant tissue loss, extensive granulation, and scarring).