Urinary System Overview

The path of filtered blood plasma (filtrate) through the kidney.

The filtering unit of the kidney, composed of the glomerulus and Bowman's capsule.

The first step of urine formation, where blood plasma is filtered into the Bowman's capsule.

The process by which valuable substances in the filtrate are returned to the bloodstream via the peritubular capillaries.

The selective movement of substances from the bloodstream into the tubular lumen.

The type of nephron characterized by a short loop of Henle, mainly located in the renal cortex.

The type of nephron with a long loop of Henle extending into the renal medulla, vital for salt gradient maintenance.

The specialized blood vessels surrounding the loop of Henle in juxtamedullary nephrons, aiding in water and salt balance.

Tiny pores in the walls of glomerular capillaries, allowing smaller waste products to pass through.

A layer surrounding the glomerular capillaries, acting as a barrier and helping to create a bridge between the capillary and Bowman's capsule.

Specialized cells that cling to the outer surface of glomerular capillaries, leaving gaps between them to facilitate filtration.

The pressure exerted by blood within the glomerular capillaries, pushing fluids and waste products into Bowman's capsule.

The vascular component of the nephron contains whole blood that is continuous with the body's general circulation. This blood remains within the body and is not filtered out.

The tubular component of the nephron contains filtered blood plasma, referred to as filtrate, which consists of waste products destined for excretion in urine.

The renal artery delivers blood containing the filtered waste to the glomerulus. This unfiltered blood then enters the afferent arteriole.

The peritubular capillaries form a network that surrounds the convoluted tubules in the nephron. They primarily exchange substances with the tubular component.

Bowman's capsule is a double-walled cup that encloses the glomerulus. Its purpose is to capture the filtrate, which includes fluid and waste products filtered out of the glomerulus.

The proximal convoluted tubule (PCT) is located after Bowman's capsule. Its main function is to reabsorb salt and water from the filtrate.

The loop of Henle is a hairpin-shaped structure that dips into the renal medulla. It has a thinner ascending limb and a thicker descending limb.

The distal convoluted tubule (DCT) is the last section of the tubular component. It connects with the collecting duct, where filtrate from other nephrons also joins.

The rate at which blood is filtered each minute within the glomerulus of the kidneys.

When blood pressure in the glomerular capillaries is high, the GFR increases. Conversely, when blood pressure is low, the GFR decreases.

This mechanism regulates blood flow into the glomerulus by constricting or dilating the afferent arteriole. This adjustment helps maintain a consistent GFR.

Hormones like renin and aldosterone play a crucial role in controlling the GFR by influencing vasoconstriction and sodium reabsorption.

The reabsorption process in the Proximal Convoluted Tubule (PCT) utilizes various transporters located in the epithelial cells. This process reclaims valuable substances from the filtrate back into the bloodstream.

The descending limb of the Loop of Henle is only permeable to water, allowing it to move out of the limb due to osmosis, concentrating the filtrate. The ascending limb is only permeable to ions like Na+ and Cl-, which are actively pumped out, creating a concentration gradient and reducing the filtrate's concentration.

The process of creating a gradient concentration difference between the interstitial fluid of the renal medulla and the filtrate within the ascending limb of the Loop of Henle. This is crucial for water conservation and urine concentration.

The descending limb of the Loop of Henle becomes more concentrated due to water leaving the filtrate, reaching a concentration of about 1200 milliosmoles. This is because the renal medulla is very salty, driving water out.

The ascending limb of the Loop of Henle becomes less concentrated as ions (Na+ and Cl-) are actively pumped out, reaching approximately 100 milliosmoles. This is because the limb is only permeable to these ions.

The process of the Loop of Henle ensuring that the filtrate entering the ascending limb has a 200 milliosmoles different than the interstitial fluid of the renal medulla. This difference is achieved by pumping out Na+ and Cl- from the filtrate.

The process of the Loop of Henle maintaining a vertical osmotic gradient in the renal medulla, using the countercurrent exchange mechanism. This gradient is crucial for water reabsorption and concentrated urine formation.

The filtrate exiting the ascending limb of the Loop of Henle contains less salt but retains waste products, contributing to the final concentrated urine.

The Loop of Henle is a specialized structure located in juxtamedullary nephrons, playing a critical role in water reabsorption and urine concentration.

The process by which the DCT and collecting duct (CD) adjust the concentration of the filtrate by actively secreting H+ and K+ into the tubules and reabsorbing water and NaCl. This ensures the final urine composition is appropriate and prevents excessive water loss.

A steroid hormone produced by the adrenal cortex, stimulated by low blood Na+ or high K+ levels. It acts on the DCT and CD, enhancing Na+ reabsorption and K+ secretion to regulate blood volume and pressure.

The process by which aldosterone regulates blood volume and pressure by increasing Na+ reabsorption and K+ secretion in the DCT and CD. This leads to increased H2O reabsorption passively, subsequently raising blood pressure and reducing urine volume.

A hormone produced in the hypothalamus and released by the posterior pituitary. It increases water permeability of the CD by inserting aquaporins, allowing for more water reabsorption and concentrated urine production, especially during dehydration.

A hormone released from the heart in response to high blood pressure. It counteracts the effects of aldosterone and ADH by promoting water and salt loss, ultimately lowering blood pressure.

The ability of the nephron to adjust its own blood flow and GFR without external nervous or hormonal control. This is essential for maintaining stable filtration rates.

The tendency of smooth muscle to contract when stretched. This mechanism contributes to renal autoregulation by adjusting afferent arteriole diameter, preserving blood flow to the glomerulus despite pressure changes.

A specialized region in the DCT where cells communicate with the glomerulus to fine-tune GFR. It involves the macula densa cells sensing changes in filtrate concentration and signaling the juxtaglomerular apparatus (JGA) to adjust.

A group of specialized cells, including the macula densa and juxtaglomerular cells, located in the DCT and afferent arteriole, respectively. They work together to regulate GFR through signaling pathways.

Specialized cells in the DCT that monitor filtrate concentration and communicate with the JGA. They signal changes in GFR, triggering adjustments in blood flow and filtration rate.