Nephron

Definition

A nephron is the functional unit of the kidney responsible for filtering blood and producing urine. Each kidney contains approximately one million nephrons, which work together to regulate water, electrolytes, and waste products in the body. The nephron plays a crucial role in maintaining homeostasis by adjusting the composition of blood and excreting excess substances.

5 Must Know Facts For Your Next Test

1. Nephrons are composed of two main parts: the renal corpuscle (which includes the glomerulus) and the renal tubule, which further divides into segments like the proximal tubule, loop of Henle, and distal tubule.
2. The filtration process in nephrons begins when blood enters the glomerulus under high pressure, allowing water and small solutes to pass through while retaining larger molecules like proteins and blood cells.
3. After filtration, the renal tubule reabsorbs about 99% of filtered water and essential nutrients back into the bloodstream, illustrating the nephron's efficiency in conserving resources.
4. Nephrons also help regulate blood pressure through the renin-angiotensin-aldosterone system (RAAS), which responds to changes in blood flow and sodium levels.
5. Damage to nephrons can lead to conditions such as chronic kidney disease, where their ability to filter waste is compromised, potentially resulting in dangerous levels of toxins in the body.

Review Questions

• Explain how the structure of a nephron contributes to its function in filtering blood.
  • The nephron's structure is tailored for efficient filtration and processing of blood. The glomerulus acts as a filter, allowing water and small solutes to pass while keeping larger molecules in circulation. Following this, the renal tubule consists of various segments that facilitate reabsorption of essential substances. This design enables nephrons to effectively maintain fluid balance and eliminate waste.
• Discuss the role of nephrons in maintaining electrolyte balance in the body.
  • Nephrons play a vital role in maintaining electrolyte balance through selective reabsorption and secretion processes. As filtrate moves through different segments of the renal tubule, specific ions such as sodium, potassium, and chloride are either reabsorbed into the bloodstream or secreted into urine based on the body's needs. Hormones like aldosterone can influence this process by promoting sodium reabsorption while facilitating potassium secretion, demonstrating how nephrons respond dynamically to maintain homeostasis.
• Evaluate the impact of nephron damage on overall kidney function and health.
  • Nephron damage significantly impacts kidney function and overall health by compromising their ability to filter waste effectively. As nephrons become damaged due to factors like diabetes or hypertension, their capacity for reabsorption decreases, leading to increased levels of waste products in the blood. This deterioration can progress to chronic kidney disease or even kidney failure if left unaddressed. Understanding nephron health is critical since it directly correlates with an individual’s overall well-being and bodily homeostasis.

Related terms

glomerulus: A network of tiny blood vessels within the nephron where filtration of blood occurs.

renal tubule: The part of the nephron that processes filtrate after it leaves the glomerulus, reabsorbing essential nutrients and water.

antidiuretic hormone (ADH): A hormone that regulates water balance in the body by influencing the permeability of the renal tubules to water.