Basement membrane

Definition

The basement membrane is a thin, fibrous extracellular matrix that separates epithelial cells from the underlying connective tissue. It plays a critical role in providing structural support, regulating cell behavior, and influencing the filtration process in organs such as the kidneys.

5 Must Know Facts For Your Next Test

1. The basement membrane is composed mainly of collagen, laminins, and proteoglycans, which contribute to its strength and flexibility.
2. In the nephron, specifically at the glomerulus, the basement membrane acts as a crucial filtration barrier that prevents larger molecules like proteins from passing into urine.
3. The basement membrane not only provides structural support but also plays a role in cell signaling, affecting cell growth, migration, and differentiation.
4. Damage to the basement membrane can lead to various diseases, including kidney disorders and issues with wound healing.
5. The basement membrane is essential for maintaining the integrity of epithelial tissue; its presence is vital for the proper function of organs like the lungs, kidneys, and skin.

Review Questions

• How does the structure of the basement membrane contribute to its function in the nephron?
  • The basement membrane's composition of collagen and other proteins provides both strength and selective permeability in the nephron. In the glomerulus, it acts as a filtration barrier that allows water and small solutes to pass while preventing larger molecules such as proteins from entering urine. This selective filtration is crucial for maintaining fluid balance and ensuring that essential substances remain in the bloodstream.
• Discuss the role of the basement membrane in maintaining epithelial tissue health and function.
  • The basement membrane is vital for supporting epithelial tissue health by anchoring epithelial cells to underlying connective tissue. It provides a stable environment that facilitates proper cellular functions such as adhesion, migration, and growth. Additionally, by regulating nutrient exchange and signaling pathways between epithelial cells and underlying tissues, the basement membrane helps maintain tissue homeostasis and repair mechanisms when damage occurs.
• Evaluate how damage to the basement membrane can impact overall organ function and contribute to disease.
  • Damage to the basement membrane can severely impact organ function by disrupting the integrity of epithelial tissues and affecting their ability to perform essential roles. For example, in kidney diseases like nephrotic syndrome, compromised basement membranes lead to protein leakage into urine, which disrupts normal homeostasis. Similarly, in lung conditions such as pulmonary fibrosis, thickening or alteration of the basement membrane affects gas exchange efficiency. Such changes often result in broader implications for organ health and can exacerbate systemic diseases.

Related terms

Extracellular matrix: A complex network of proteins and carbohydrates that provide structural and biochemical support to surrounding cells.

Filtration barrier: A selective barrier that allows certain substances to pass while preventing others, particularly important in the kidneys where the basement membrane plays a key role.

Epithelial cells: Cells that line the surfaces of organs and structures throughout the body, forming protective barriers and involved in absorption, secretion, and sensation.