Basement membrane

Definition

The basement membrane is a thin, fibrous extracellular matrix layer that underlies epithelial and endothelial cells, providing structural support and regulating cellular functions. It acts as a barrier and interface between tissues, influencing cell adhesion, migration, and differentiation, and plays a critical role in cell-matrix interactions and signaling.

5 Must Know Facts For Your Next Test

1. The basement membrane consists of two layers: the basal lamina, which is closer to the epithelium, and the reticular lamina, which connects it to underlying connective tissue.
2. It is composed mainly of proteins like collagen IV, laminin, and entactin, which together form a mesh-like structure that provides strength and flexibility.
3. The basement membrane plays a crucial role in tissue regeneration and repair by regulating cell behavior during wound healing.
4. It acts as a selective barrier, influencing the movement of molecules and cells between different tissue compartments.
5. Dysfunction or alteration of the basement membrane can lead to various diseases, including cancer metastasis and kidney disorders.

Review Questions

• How does the structure of the basement membrane contribute to its functions in tissue organization?
  • The basement membrane's structure, comprising layers of proteins like collagen IV and laminin, allows it to provide both support and filtration capabilities. This layered architecture helps maintain tissue organization by anchoring epithelial cells while also enabling communication between cells through signaling pathways. The unique composition of the basement membrane creates an environment that influences cellular behavior such as adhesion and migration.
• Discuss the role of laminin in cell adhesion and migration within the context of the basement membrane.
  • Laminin is a critical component of the basement membrane that facilitates cell adhesion and migration. It binds to cell surface receptors such as integrins, promoting stable connections between cells and the extracellular matrix. This interaction not only helps anchor cells but also initiates signaling cascades that regulate cell movement during processes like wound healing and tissue development.
• Evaluate how changes in basement membrane composition can lead to pathological conditions, citing specific examples.
  • Alterations in basement membrane composition can significantly impact tissue integrity and function, leading to various pathological conditions. For instance, in cancer, changes in components like collagen can promote tumor invasion and metastasis by allowing cancer cells to detach from primary tumors and migrate to other sites. Additionally, in diabetic nephropathy, thickening of the basement membrane in kidney glomeruli disrupts normal filtration processes, contributing to kidney dysfunction. These examples illustrate how essential the basement membrane is for maintaining healthy tissue homeostasis.

Related terms

Collagen: A primary structural protein in the extracellular matrix, providing strength and support to tissues, including the basement membrane.

Fibronectin: An adhesive glycoprotein that helps cells attach to the extracellular matrix and plays a role in cell migration and wound healing.

Laminin: A key component of the basement membrane that influences cell behavior and provides a scaffold for tissue structure.