What are six main tasks that the kidney perform?

The kidneys perform several essential tasks, including filtering waste products and excess substances from the blood to form urine, regulating electrolyte balance by controlling the levels of sodium, potassium, and calcium, and maintaining acid-base balance to help stabilize the body's pH. They also regulate blood pressure through the renin-angiotensin-aldosterone system, produce erythropoietin to stimulate red blood cell production in response to low oxygen levels, and contribute to vitamin D metabolism, which is crucial for calcium absorption and bone health.