Introduction

Interstitial fluid is the fluid that surrounds and bathes the body’s cells. It serves as the medium through which oxygen, nutrients, hormones, and other essential substances are delivered from the bloodstream to the tissues, while carbon dioxide and metabolic waste products are removed from the cells.

Interstitial fluid is an essential component of the extracellular fluid (ECF) and acts as the critical bridge between the blood circulatory system and the lymphatic system.

Under normal physiological conditions, interstitial fluid is continuously formed from blood plasma and is constantly exchanged with the blood and lymphatic systems to maintain tissue homeostasis.

What is Interstitial Fluid?

Interstitial fluid is blood plasma that has filtered out of blood capillaries into the spaces between cells, known as the interstitial spaces.

It surrounds nearly every cell in the body, providing a stable environment for cellular function.

Before entering the lymphatic system, the fluid is called interstitial fluid. Once it enters a lymphatic capillary, it is called lymph.

Where is Interstitial Fluid Located?

Interstitial fluid is found in the microscopic spaces between cells throughout almost every tissue of the body.

It surrounds:

Muscle cells

Skin cells

Connective tissue

Blood vessels

Organs

Nerves

These spaces are known as the interstitial spaces or interstitial compartments.