Kidney Function: Ultrafiltration and Reabsorption

The process where blood is filtered in the kidneys, forcing fluids and small molecules out of the glomerulus and into Bowman's capsule. This is the first step in urine formation.

The process of reabsorbing useful substances - like water, glucose, and amino acids - back into the bloodstream from the nephron tubules, after ultrafiltration.

These are tiny blood vessels that bring blood into the glomerulus for filtration. They are wider than the efferent arterioles, which helps create pressure for ultrafiltration.

These are tiny blood vessels that carry blood away from the glomerulus after filtration. They are narrower than the afferent arterioles, which further increases pressure inside the glomerulus.

This is a network of tiny blood vessels within Bowman's capsule, where ultrafiltration takes place.

This is a cup-like structure at the start of the nephron, where ultrafiltration occurs. The glomerulus sits inside this structure.

This is the fluid formed by ultrafiltration in the nephron, containing water, glucose, mineral ions, and other small molecules, but not blood cells or proteins.

These are specialized capillaries that surround the tubules of the nephron, playing a role in reabsorbing substances from the filtrate back into the blood.

The proximal convoluted tubule is the first part of the nephron where most of the filtrate is reabsorbed back into the blood.

The loop of Henlé is a hairpin-shaped tubule that extends into the medulla of the kidney. It helps to concentrate urine by creating a gradient of salt concentration.

The descending limb of the loop of Henlé is permeable to water but not to salts, allowing water to move out of the filtrate and into the interstitial fluid.

The ascending limb of the loop of Henlé is impermeable to water but permeable to salts, allowing salts to move out of the filtrate and into the interstitial fluid.

The distal convoluted tubule is the second part of the nephron where fine adjustments to the composition of the filtrate are made. It controls pH and adjusts the levels of water and salts.

The counter-current multiplier system is a mechanism used by the loop of Henlé to create a concentration gradient in the medulla of the kidney. This gradient allows for the reabsorption of water from the collecting duct.

Microvilli are tiny finger-like projections that increase the surface area of cells, allowing for more efficient absorption of substances from the filtrate.

Mitochondria are organelles within cells that produce energy (ATP) for cellular processes, such as active transport.

Special cells in the glomerulus that have foot-like processes, creating gaps for filtration. They play a crucial role in preventing large molecules from entering the filtrate.

The membrane that separates the blood in the glomerulus from the space inside the renal capsule. It acts as a barrier, allowing small molecules like water and waste products to pass through.

The tiny projections of the podocyte cells that interlock, forming slits that regulate the passage of substances during filtration.

The first part of the renal tubule where most reabsorption occurs. It features microvilli, which increase its surface area for efficient reabsorption.

Tiny finger-like projections on the epithelial cells of the PCT that increase surface area for reabsorption. They enhance the efficiency of reabsorbing important substances from the filtrate.

The process that occurs in the glomerulus where blood is filtered, separating waste products and small molecules from the blood.