Excretory Processes,”1) Filtration. The excretory tubule collects a filtrate from the blood.Water and solutes are forced by blood pressure across the selectively permeable membranes of a cluster of capillaries and into the excretory tubule.2) Reabsorption. The transport epithelium reclaims valuable substances from the filtrate and returns them to the body fluids.3) Secretion. Other substances, such as toxins and excess ions
are extracted from body fluids and added to the contents of the excretory tubule.4) Excretion. The filtrate leaves the system and the body.”