* Water: The primary component of the filtrate.
* Small solutes:
* Electrolytes: Sodium, potassium, chloride, bicarbonate, calcium, phosphate, magnesium.
* Nutrients: Glucose, amino acids.
* Waste products: Urea, creatinine, uric acid.
* Hormones: Some hormones are filtered out but are usually reabsorbed later.
* Small proteins: While large proteins are typically blocked by the filtration barrier, small proteins can pass through.
Substances NOT present in the capsular space:
* Blood cells: Red blood cells, white blood cells, platelets.
* Large proteins: Albumin, globulins.
* Lipids: Fats and cholesterol.
Important Notes:
* The composition of the capsular space is constantly changing as substances are reabsorbed and secreted along the nephron.
* The filtration barrier, composed of the capillary endothelium, basement membrane, and podocytes, prevents the passage of large molecules and cells into the capsular space.
* The substances in the capsular space are eventually processed through the renal tubules and either excreted in the urine or reabsorbed back into the bloodstream.
