Formation of Urine (Basic Renal Process) Flashcards
What are the three main processes involved in urine formation?
Glomerular filtration, tubular reabsorption, and tubular secretion.
What is glomerular filtration?
The process by which the kidneys filter blood, removing excess wastes and fluids.
Where does glomerular filtration occur?
In the glomerulus of the nephron.
What drives the glomerular filtration process?
Blood pressure forces plasma and small solutes through the glomerular capillary walls.
What is the composition of the filtrate produced in the glomerulus?
Filtrate contains water, ions, glucose, amino acids, and small proteins, but no blood cells or large proteins.
How is the glomerular filtration rate (GFR) regulated?
Through intrinsic (autoregulation) and extrinsic (hormonal and neural) mechanisms.
What is the role of the afferent and efferent arterioles in GFR regulation?
Afferent arteriole dilation increases GFR, while efferent arteriole constriction also increases GFR.
What is tubular reabsorption?
The process of moving substances from the filtrate back into the blood.
Where does the majority of tubular reabsorption take place?
In the proximal convoluted tubule.
What substances are primarily reabsorbed in the proximal convoluted tubule?
Sodium, water, glucose, amino acids, and bicarbonate.
How is sodium reabsorbed in the proximal convoluted tubule?
Via active transport mechanisms involving sodium-potassium ATPase pumps.
What is the role of the loop of Henle in urine concentration?
To create a concentration gradient that allows for the reabsorption of water.
How does the countercurrent multiplier mechanism function in the loop of Henle?
It multiplies the osmotic gradient through active transport of sodium and chloride in the ascending limb.
What is tubular secretion?
The transfer of substances from the blood into the tubular fluid.
Where does tubular secretion primarily occur?
In the distal convoluted tubule and collecting ducts.
What are the main substances secreted in the distal convoluted tubule?
Potassium, hydrogen ions, and certain drugs.
How does the collecting duct contribute to urine concentration?
By adjusting the reabsorption of water, influenced by hormones like ADH.
What is the role of antidiuretic hormone (ADH) in the collecting duct?
ADH increases the permeability of the collecting ducts to water, enhancing reabsorption.
How does aldosterone affect the distal convoluted tubule and collecting duct?
Aldosterone increases sodium reabsorption and potassium secretion.
What is the significance of the juxtaglomerular apparatus in renal function?
It regulates blood pressure and GFR through the release of renin.
How does the macula densa contribute to the regulation of GFR?
By sensing sodium chloride concentration in the distal tubule and adjusting renin release.
What is the function of renin released by the juxtaglomerular cells?
Renin activates the RAAS, increasing blood pressure and sodium retention.
How does angiotensin II affect kidney function?
Angiotensin II constricts blood vessels and stimulates aldosterone release, increasing blood pressure.
What is the importance of maintaining a stable GFR?
To ensure efficient filtration and reabsorption of essential substances.
