The nephrons in the kidneys are responsible for filtering blood and removing waste products. However, not all substances are filtered through the nephrons. Here are some substances that are not filtered:
- Proteins: Large proteins, such as albumin, are generally not filtered through the nephrons. They are too large to pass through the filtration barrier in the glomerulus.
- Blood Cells: Red and white blood cells are not filtered. Their size prevents them from passing through the glomerular filtration barrier.
- Platelets: Similar to blood cells, platelets are also too large to be filtered through the nephrons.
- Large Molecules: Molecules that are too large to pass through the filtration barrier, such as certain lipids and polysaccharides, are not filtered.
- Bound Substances: Substances that are bound to proteins in the blood, such as some hormones and drugs, are not filtered because they are attached to larger molecules.
These substances remain in the blood and are not excreted in the urine unless there is a problem with the filtration barrier, such as in certain kidney diseases.