The urinary system maintains blood homeostasis by filtering out excess fluid and other substances from the bloodstream and secreting waste. Learning Objectives Key Points
Key Terms
The Renal SystemThe renal system, which is also called the urinary system, is a group of organs in the body that filters out excess fluid and other substances from the bloodstream. The purpose of the renal system is to eliminate wastes from the body, regulate blood volume and pressure, control levels of electrolytes and metabolites, and regulate blood pH. The renal system organs include the kidneys, ureters, bladder, and urethra. Metabolic wastes and excess ions are filtered out of the blood, along with water, and leave the body in the form of urine. Components of the renal system: Here are the major organs of the renal system. Renal System FunctionsThe renal system has many functions. Many of these functions are interrelated with the physiological mechanisms in the cardiovascular and respiratory systems.
Many of these functions are related to one another as well. For example, water follows ions via an osmotic gradient, so mechanisms that alter sodium levels or sodium retention in the renal system will alter water retention levels as well. Organs of the Renal SystemKidneys and NephronsKidneys are the most complex and critical part of the urinary system. The primary function of the kidneys is to maintain a stable internal environment (homeostasis) for optimal cell and tissue metabolism. The kidneys have an extensive blood supply from the renal arteries that leave the kidneys via the renal vein. Nephrons are the main functional component inside the parenchyma of the kidneys, which filter blood to remove urea, a waste product formed by the oxidation of proteins, as well as ions like potassium and sodium. The nephrons are made up of a capsule capillaries (the glomerulus) and a small renal tube. The renal tube of the nephron consists of a network of tubules and loops that are selectively permeable to water and ions. Many hormones involved in homeostasis will alter the permeability of these tubules to change the amount of water that is retained by the body. UreterUrine passes from the renal tube through tubes called ureters and into the bladder. BladderThe bladder is flexible and is used as storage until the urine is allowed to pass through the urethra and out of the body. UrethraThe female and male renal system are very similar, differing only in the length of the urethra. Human OsmoregulationThe kidneys play a very large role in human osmoregulation by regulating the amount of water reabsorbed from the glomerular filtrate in kidney tubules, which is controlled by hormones such as antidiuretic hormone (ADH), renin, aldosterone, and angiotensin I and II. A basic example is that a decrease in water concentration of blood is detected by osmoreceptors in the hypothalamus, which stimulates ADH release from the pituitary gland to increase the permeability of the wall of the collecting ducts and tubules in the nephrons. Therefore, a large proportion of water is reabsorbed from fluid to prevent a fair proportion of water from being excreted. The extent of blood volume and blood pressure regulation facilitated by the kidneys is a complex process. Besides ADH secretion, the renin-angiotensin feedback system is critically important to maintain blood volume and blood pressure homeostasis. LICENSES AND ATTRIBUTIONS CC LICENSED CONTENT, SHARED PREVIOUSLY
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How does the digestive and urinary system maintain homeostasis?The excretory system works with the endocrine system to help maintain homeostasis. Chemical messengers called hormones signal the kidneys to filter more or less water or salt, depending on the levels of water and salt in the body. For example, when you sweat a lot the water content of your blood can drop.
How does the urinary and digestive system work together?The urinary system works as a filter, removing toxins and wastes from your body through urine. It uses a series of tubes and ducts to pass this waste. These tubes are connected to your blood vessels and digestive system. Your urinary system helps the rest of your body work properly.
How does the digestive system work with other systems to maintain homeostasis?The digestive system maintains homeostasis by ensuring that the stomach environment has the right pH balance. The body uses both positive and negative mechanisms to maintain homeostasis. When the body detects an imbalance, the various systems work together to counterbalance and restore correct equilibrium.
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