---
title: "Junctions, Adhesion and the Extracellular Matrix"
description: "Cells hold onto each other and onto the matrix around them through junctions that are anchored to the cytoskeleton. The matrix is not filler: its stiffness and composition feed back into how the cell "
canonical: https://lightmysky.com/learn/science/junctions-adhesion-and-the-extracellular-matrix-mt_Sjcd3kQUmw
source: https://lightmysky.com/learn/science/junctions-adhesion-and-the-extracellular-matrix-mt_Sjcd3kQUmw.md
retrieved: 2026-09-12
---

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# Junctions, Adhesion and the Extracellular Matrix

Cells hold onto each other and onto the matrix around them through junctions that are anchored to the cytoskeleton. The matrix is not filler: its stiffness and composition feed back into how the cell behaves.

Subject: Science · Area: Organisms & Life Processes · Ages 20 to 22
Page: https://lightmysky.com/learn/science/junctions-adhesion-and-the-extracellular-matrix-mt_Sjcd3kQUmw

## Ready when they can

- Matches a junction type to the job it does: sealing, anchoring or letting small molecules pass.
- Explains why an anchoring junction is useless unless it connects to filaments inside the cell.
- Gives one example of matrix stiffness changing what a cell does.

## Lesson: Seal it, weld it, or wire it

Animal cells fasten to each other with three junction styles, one per job. Tight junctions stitch membranes into leak proof belts that seal. Anchoring junctions weld cells to each other and to the matrix, and gap junctions open gated tunnels that let small molecules pass.

An anchoring junction holds nothing unless it ties to something solid inside. Its linkers grip filaments of the cytoskeleton, so pulling forces spread across the sheet instead of ripping the junction out of the membrane. Cells grip the matrix the same way through integrins, which hold the mesh outside and the filaments inside, carrying force and signals both ways.

**Example.** The matrix around the cells is a mesh of collagen for strength, elastin for stretch, and sticky glycoproteins that link cells to it. Cells read its stiffness through their adhesions and change fate: stem cells on stiff ground lean toward bone, while the same cells on soft ground lean toward nerve or fat.

**Tip.** When you meet a junction, first name its job as sealing, anchoring, or passing, then check what it connects to on each side.

**Recap.** Match each junction to its job, and remember that anchors only hold when tied to filaments.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Tissue Types and How a Body Is Organised](https://lightmysky.com/learn/science/tissue-types-and-how-a-body-is-organised-mt_dQ-glI4kdz)
- [Motor Proteins and Directed Movement Along Tracks](https://lightmysky.com/learn/science/motor-proteins-and-directed-movement-along-tracks-mt_TUTmILr7y0)

## Opens up

- [Gastrulation and Laying Down the Body Axes](https://lightmysky.com/learn/science/gastrulation-and-laying-down-the-body-axes-mt_PABfw_4RPs)