Tissue Repair MCQs

Ans. is 'b' i.e., End of second week During second week there is continued accumulation of collagen and proliferation of fibroblast. Maximum collagen is seen in second week.

Platelets are disc-shaped anucleate cell fragments that are shed from megakaryocytes in the bone marrow into the bloodstream. Their function depends on several glycoprotein receptors, a contractile cytoskeleton, and two types of cytoplasmic granules. α-Granules have the adhesion molecule P-selectin on their membranes and contain proteins involved in coagulation, such as fibrinogen, coagulation factor V, and vWF, as well as protein factors that may be involved in wound healing, such as fibronectin, platelet factor 4 (a heparin-binding chemokine), platelet-derived growth factor (PDGF), and transforming growth factor-β. Dense (or δ) granules contain adenosine diphosphate (ADP) and adenosine triphosphate, ionized calcium, serotonin, and epinephrine. Reference :Robbins, 10th edition, page number - 102

Interstitial matrix is produced by mesenchymal cells like fibroblasts and is mainly composed of fibrillar and non-fibrillar collagen. TGF-beta is chemotactic for leukocytes and fibroblasts. It induces proliferation of fibroblasts. Reference: Robbins & Cotran Pathologic Basis of Diseases 10 th edition, chapter 3, pg 85

Healing is modified by a number of influences(including both systemic and local host factors) frequently impairing the quality and adequacy of both inflammation and repair. Ascorbic acid deficiency causes reduced cross linking of tropocollagen to collagen So, the patient has increased bleeding tendencies and poor wound healing. Reference: Robbins & Cotran Pathologic Basis of Diseases 10 th edition, chapter 3, pg 108

Option a-true-Three phases of wound healing-Inflammation(early & late), Granulation tissue formation & re-epithelialization and Wound contraction, ECM deposition & remodelling Strength never reaches 100% Q Option d - The recovery of tensile strength results from the excess of collagen Synthesis over collagen degradation during the first 2 months of healing and at later times, from structural modifications of collagen fibers(cross-linking, increased fiber size) option D. Reference: Robbins & Cotran Pathologic Basis of Diseases 10 th edition, chapter 3, pg 108

Astrocyte Injury and Repair. Astrocytes are the principal cells responsible for repair and scar formation in the brain, a process termed gliosis. In response to injury, astrocytes undergo both hypertrophy and hyperplasia. The nucleus enlarges and becomes vesicular, and the nucleolus becomes prominent. The cytoplasm expands and takes on a bright pink hue, and the cell extends multiple stout, ramifying processes called gemistocytic astrocyte. Reference: Robbins Basic Pathology, 10 th edition, Page: 850

Fibrillar collagens(mostly type I collagen) form a major portion of the connective tissue in repair sites and are essential for the development of strength in healing wounds. Net collagen accumulation, however, depends not only on increased collagen synthesis but also on decreased degradation. The recovery of tensile strength results from the excess of collagen synthesis over collagen degradation during the first 2 months of healing and at later times, from structural modifications of collagen fibers(cross-linking, increased fiber size) after collagen synthesis ceases. Reference: Robbins & Cotran Pathologic Basis of Diseases 10 th edition, chapter 3, pg 107

FETAL WOUNDS DO NOT FORM SCAR REPAIR Reference: Robbins & Cotran Pathologic Basis of Diseases 10 th edition, chapter 3, pg 103