Key Stage 3 (KS3) Biology Practice Test

Tissue fluid is a crucial component in the body, as it plays a key role in the exchange of substances between the blood and the cells. It originates from the process of filtration in the capillaries. As blood flows through the capillaries, the pressure causes some fluid to leak out of the blood vessels and into the surrounding tissues, creating tissue fluid.

This fluid serves to bathe the cells, providing them with oxygen and nutrients while also helping to remove waste products. The composition of tissue fluid closely resembles that of blood plasma, but it lacks significant proteins since larger molecules typically remain in the blood to maintain oncotic pressure.

Understanding the source of tissue fluid is essential as it highlights the dynamic exchange between the circulatory system and the individual cells, facilitating essential bodily functions such as nutrient delivery and waste removal.