Article
The kidneys help the body remove waste products and maintain a stable internal environment. They regulate water and electrolyte balance, contribute to blood pressure regulation, and support other important physiological processes. For students preparing for the ATI TEAS exam, understanding kidney function can help connect anatomy, circulation, and homeostasis.
1. Identify the main urinary system organs
The urinary system includes the kidneys, ureters, urinary bladder, and urethra. The kidneys produce urine. The ureters transport urine from the kidneys to the bladder, where it is stored temporarily. The urethra carries urine from the bladder out of the body. Each structure has a different role, so avoid treating the urinary system as if every organ performs the same function.
2. Understand what the kidneys remove
Blood carries metabolic waste products and substances that must be regulated. The kidneys filter blood and adjust the amounts of water and dissolved substances returned to the bloodstream or excreted in urine. One important waste product is urea, which is produced when the body processes nitrogen-containing compounds, including those derived from protein metabolism. Healthy kidneys also help maintain appropriate levels of electrolytes, such as sodium and potassium, within the body.
3. Learn about nephrons
A nephron is the functional unit of the kidney. Each kidney contains many nephrons that work together to form urine. A nephron includes a renal corpuscle and a renal tubule. The renal corpuscle contains a cluster of capillaries called the glomerulus, surrounded by Bowman's capsule. The tubule processes the fluid produced by filtration. Learning the basic nephron structure makes it easier to understand the stages of urine formation.
4. Understand filtration, reabsorption, and secretion
Urine formation involves several processes. Filtration: Water and small dissolved substances move from blood in the glomerulus into Bowman's capsule. Blood cells and most large proteins normally remain in the bloodstream. Reabsorption: The tubules return useful substances and varying amounts of water to the blood. These substances can include glucose, electrolytes, and other materials the body needs to retain. Secretion: Certain substances move from the blood into the tubular fluid for removal. The fluid that remains becomes urine after further processing along the nephron and collecting system.
5. Connect the kidneys to homeostasis
Homeostasis means maintaining relatively stable internal conditions despite changes inside or outside the body. The kidneys contribute by adjusting how much water and electrolytes are retained or excreted. They also help regulate acid-base balance. Hormones influence these processes. For example, antidiuretic hormone helps the body conserve water by increasing water reabsorption in appropriate parts of the kidney's collecting system. When water conservation increases, urine generally becomes more concentrated. When less water is reabsorbed, a larger volume of more dilute urine may be produced.
6. Understand the relationship between kidneys and blood pressure
The kidneys contribute to blood pressure regulation by controlling fluid balance and through hormonal mechanisms, including the renin-angiotensin-aldosterone system. Changes in sodium and water handling can affect blood volume, which in turn can influence blood pressure. The relationship is complex, so avoid assuming that every change in blood pressure results from one kidney mechanism alone.
7. Avoid common study mistakes
A common mistake is confusing the ureter with the urethra. Remember that the ureters carry urine from the kidneys to the bladder, while the urethra carries urine from the bladder out of the body. Another mistake is thinking that filtration and reabsorption are identical. Filtration moves fluid out of the blood into the nephron, while reabsorption returns selected substances from the tubular fluid to the blood.
Practice for TEAS science
Draw a simple urinary system diagram and label each organ. Then outline the path urine takes from its formation to its exit from the body. Review the nephron and explain filtration, reabsorption, and secretion in your own words. Practice questions that connect kidney function with fluid balance and homeostasis.
