In regard to the kidney, Why is everything dumped into the tubule? Why not dump only wastes and toxins like insects?
The function of the kidneys is to filter the blood and remove waste products, excess fluid, and toxins from the body. The process of filtering the blood occurs within tiny structures in the kidneys called nephrons.
The nephrons consist of a glomerulus, which is a network of tiny blood vessels, and a tubule, a long, coiled structure. When blood flows through the glomerulus, water, salts, and small molecules such as wastes and toxins are filtered from the blood into the tubule.
Now, your question is why everything is dumped into the tubule, and why not just dump only wastes and toxins like insects. The reason for this is that the kidneys have an important role in maintaining the balance of our body's fluids, electrolytes, and pH levels.
By excreting both waste products and useful substances, the kidneys help regulate the concentration of important substances in our body, like sodium, potassium, and calcium. Additionally, the kidneys also reabsorb certain substances, such as glucose and amino acids, back into the bloodstream if the body needs them.
So, if the kidneys only dumped wastes and toxins like insects, we would also lose essential substances that our body needs to function properly. By filtering everything into the tubules, the kidneys are able to carefully regulate what is excreted and what is reabsorbed, maintaining a balance of necessary substances and eliminating waste products at the same time.