Blood Components in Tissue Fluid

Steps:

• Recall tissue fluid forms by filtration from blood capillaries, allowing small molecules and some cells to pass.
• Identify phagocytes (white blood cells) can migrate through capillary walls into tissues via diapedesis.
• Note small proteins and ions like sodium diffuse freely, while large proteins and red blood cells remain in blood.
• Match components: phagocytes present, some proteins present, sodium ions present—selecting option indicating all three.

Why A is correct:

• Tissue fluid, by definition, contains soluble plasma components (ions, small proteins) and migratory leukocytes (phagocytes) per Starling's forces on capillary exchange.

Why the others are wrong:

• B incorrectly implies all components absent or mismatched to the query's full presence.
• C wrongly excludes sodium ions, which freely diffuse into interstitial spaces.
• D erroneously limits to only sodium ions, ignoring phagocytes and proteins.

Final answer: A