Lecture 4.1 - Regeneration and repair 2

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Questions and Answers

What type of collagen is responsible for providing the extracellular framework in hard and soft tissues?

Type I (fibrillar) collagen (correct)

Type III (fibrillar) collagen

Type IV (basement membrane) collagen

Type II (network-forming) collagen

What process occurs in the granulation tissue stage of fibrous repair, leading to wound contraction?

Phagocytosis of necrotic tissue debris

Synthesis of collagen by fibroblasts

Contraction of fibrils within myofibroblasts (correct)

Proliferation of endothelial cells

What is the primary function of collagen in the fibrous repair process?

To provide a scaffold for cell proliferation

To facilitate cell migration and differentiation

To provide the extracellular framework for tissue structure (correct)

To synthesise growth factors and cytokines

What is the repeating sequence found in the collagen triple helix?

Gly-x-y Signup and view all the answers

Why does fibrous repair occur in response to tissue injury?

All of the above Signup and view all the answers

What is the primary cell type responsible for synthesising collagen during fibrous repair?

Fibroblasts Signup and view all the answers

What is the term for the process of new capillary growth into the wounded area?

Angiogenesis Signup and view all the answers

What is the mature form of granulation tissue following fibrous repair?

Fibrous scar Signup and view all the answers

What is the primary function of vitamin C in collagen synthesis?

Hydroxylation of procollagen Signup and view all the answers

What is the characteristic feature of Ehlers-Danlos syndrome?

Hyperextensible skin and joint hypermobility Signup and view all the answers

What is the result of abnormal type IV collagen in Alport syndrome?

Dysfunction of the glomerular basement membrane Signup and view all the answers

What is the consequence of collagen defects in Scurvy?

Impaired wound healing and capillary fragility Signup and view all the answers

Which of the following is NOT a characteristic of Osteogenesis imperfecta?

Hyperextensible skin and joint hypermobility Signup and view all the answers

What is the final step in collagen synthesis?

Cross-linking of collagen molecules Signup and view all the answers

What is the role of fibroblasts in collagen synthesis?

To synthesize collagen Signup and view all the answers

What is the result of the cross-linking of collagen molecules?

Tensile strength of collagen Signup and view all the answers

What is the primary role of adult stem cells in regeneration?

To replace used cells constantly Signup and view all the answers

Which type of stem cells are found in cord blood and are rich in mesenchymal stem cells (MSC) and HSC?

Cord blood stem cells Signup and view all the answers

What is the characteristic of labile tissues?

They have a normal state of active cell division and rapid proliferation for regeneration Signup and view all the answers

What is the classification of stem cells based on their differentiation potential?

Based on their differentiation potential Signup and view all the answers

What is the characteristic of stem cells that are unipotent?

They can only produce one cell type but have the property of self-renewal Signup and view all the answers

What is the role of bone marrow-derived stem cells?

They produce multipotent haematopoietic stem cells and EPC Signup and view all the answers

What is the difference between regeneration and healing?

Regeneration is the constant replacement of cells, while healing is the regeneration and repair of tissues Signup and view all the answers

What is the characteristic of induced pluripotent stem cells?

They are derived from adult tissues and are pluripotent Signup and view all the answers

Study Notes

Collagen Synthesis

Collagen is synthesized by fibroblasts and myofibroblasts through the following process:
Preprocollagen is produced in the cell, modified to procollagen, and secreted from the cell.
Procollagen is then cleaved to produce fibrillar collagen with considerable cross-linking between molecules, providing tensile strength.

Scurvy: a disease caused by vitamin C deficiency, which is required for hydroxylation of procollagen, leading to poor wound healing and fragile capillaries.
Ehlers-Danlos syndrome: a group of inherited disorders characterized by collagen fibers with inadequate tensile strength, resulting in hyperextensible skin, fragile joints, and poor wound healing.
Osteogenesis imperfecta: a disease characterized by brittle bones, blue sclerae, hearing impairment, and dental abnormalities due to inadequate collagen.
Alport syndrome: an X-linked disease caused by abnormal type IV collagen, leading to dysfunction of the glomerular basement membrane, cochlea, and lens of the eye, resulting in hematuria, chronic renal failure, neural deafness, and eye disorders.

Fibrous Repair/Organization

Fibrous repair occurs when the collagen framework of a tissue is destroyed, there is chronic inflammation, or necrosis of specialized parenchymal cells that cannot be replaced.
The process involves phagocytosis of necrotic tissue debris, angiogenesis, proliferation of fibroblasts and myofibroblasts, and the formation of granulation tissue, which matures into a fibrous scar.
Collagen synthesis is essential for fibrous repair.

Collagen Structure and Function

Collagen is the most common protein in the animal world, with 27 different types.
Type I (fibrillar) collagen is the most common type in the body, present in hard and soft tissues.
Collagen consists of a triple helix of three polypeptide alpha chains with a gly-x-y repeating sequence.

Stem Cells

Classification of stem cells based on their differentiation potential: pluripotent, multipotent, and unipotent.
Types of stem cells: embryonic stem cells, adult stem cells, induced pluripotent stem cells, and cord blood stem cells.
Roles of adult stem cells in regeneration: replacement of used cells, healing, and regrowth.
Adult stem cells in different tissues have different roles in healing, such as bone marrow-derived stem cells that produce multipotent haematopoietic stem cells.

Regenerative Capacity of Cells and Tissues

Cells can be classified into three groups based on proliferative activity and link to their stem cells: labile, stable, and permanent.
Labile tissues continuously divide and have rapid proliferation for regeneration.
Stable tissues are quiescent and have variable speeds of regeneration.
Permanent tissues are non-dividing and have no effective regeneration.

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Description

This quiz covers the process of collagen synthesis by fibroblasts and myofibroblasts, including the production of preprocollagen, procollagen, and fibrillar collagen. It also touches on diseases caused by defects in collagen production.