Renal Physiology Quiz

Paired, bean-shaped organs located along the back body wall below the diaphragm and adjacent to the vertebral column. The right kidney is lower than the left due to the liver's presence.

The renal arteries deliver approximately 1/4 of the cardiac output to the kidneys each minute.

The kidneys filter waste products, regulate blood volume and composition, produce hormones, and activate vitamin D.

The nephron is the functional unit of the kidney, responsible for filtering blood and producing urine. It consists of several components, including the glomerulus, Bowman's capsule, proximal tubule, loop of Henle, distal tubule, and collecting duct.

Glomerular filtration is the first step in urine formation, where fluid and small solutes are filtered from the blood into Bowman's capsule. The process is driven by blood pressure.

Tubular reabsorption occurs in the renal tubules, where useful substances like water, glucose, and amino acids are reabsorbed back into the bloodstream. This helps conserve essential nutrients and regulates blood volume.

Tubular secretion is when the renal tubules actively transport waste products and excess ions from the blood into the tubular fluid. These substances are then eliminated from the body in urine.

The kidneys play a vital role in regulating fluid balance, blood pressure, and electrolyte concentrations in the body, contributing to the overall homeostasis of the body.

The functional and structural units of the kidney responsible for forming urine. There are about 1 million nephrons in each kidney.

The first segment of a nephron, responsible for filtering blood.

A network of tiny blood vessels located within the renal corpuscle, where filtration occurs.

The part of the nephron extending outward from the renal corpuscle, responsible for reabsorbing and secreting substances.

Nephrons located in the outer portion of the kidney cortex with short loops of Henle.

Nephrons located deep in the cortex, close to the medulla with long loops of Henle.

The process of separating water and small solutes from blood in the glomerulus.

The return of filtered substances from the renal tubules back into the bloodstream.

The transfer of substances from the blood into the lumen of the renal tubules for excretion.

The process of regulating the glomerular filtration rate (GFR), the amount of blood filtered by the kidneys per minute.

Angiotensin II is a powerful vasoconstrictor, narrowing both afferent and efferent arterioles. This constriction reduces blood flow into glomeruli and increases pressure in the glomerular capillaries, ultimately lowering the filtration rate (GFR).

Atrial Natriuretic Peptide (ANP) is released by the heart's atria in response to a sharp rise in blood pressure. ANP counteracts this elevated pressure by dilating the afferent arterioles in the glomerulus, enhancing blood flow, and increasing the glomerular filtration surface area.

Paracellular reabsorption occurs between cells of the renal tubule, allowing water and small solutes to move through the tight junctions, the spaces between these cells.

Transcellular reabsorption involves the movement of water and solutes through tubular cells, crossing two membranes: the apical membrane facing the tubular lumen and the basolateral membrane on the other side, before entering the interstitial fluid and then the capillaries to return to the bloodstream.

The Sodium-Potassium pump (Na⁺--K⁺ ATPase) is a vital protein found on the basolateral membrane of renal tubule cells. It actively pumps Na⁺ ions out of the cells into the interstitial fluid, while simultaneously pumping K⁺ ions into the cells, consuming ATP in the process. This creates a concentration gradient that drives further reabsorption of Na⁺ from the tubular fluid.

A hormone released by the posterior pituitary gland in response to low blood flow in the brain. It increases the water permeability of principal cells in the distal convoluted tubule and collecting duct, facilitating water reabsorption and concentrating urine.

A hormone produced by the adrenal cortex that acts on the distal convoluted tubules of the nephron. It promotes the reabsorption of sodium (Na+) and the secretion of potassium (K+), ultimately increasing blood volume and pressure.

A hormone released by the parathyroid gland. It stimulates calcium (Ca2+) reabsorption in the early distal convoluted tubule, increasing blood calcium levels. It also inhibits phosphate reabsorption in the proximal convoluted tubule, promoting phosphate excretion.

A hormone released by the heart's atria in response to high blood volume. It promotes sodium (Na+) and water excretion by the kidneys, decreasing blood volume and pressure.

A potent vasoconstrictor hormone that is produced by the liver. It acts on various organs and systems, including the blood vessels, heart, kidneys, and adrenal glands. Its main function is to regulate blood pressure and fluid balance.

Glucose exits the proximal convoluted tubule (PCT) via facilitated diffusion through the basolateral membrane, moving into the interstitial fluid and subsequently into the peritubular capillaries.

Sodium (Na+) reabsorption in the PCT is driven by a sodium-hydrogen (Na+-H+) antiporter, where Na+ moves down its concentration gradient into the PCT cells, simultaneously pumping H+ into the tubular fluid.

Carbonic anhydrase, an enzyme present in the PCT, catalyzes the reaction between Carbon dioxide (CO2) and water (H2O) to form carbonic acid (H2CO3), which subsequently dissociates into H+ and bicarbonate ions (HCO3-), providing H+ for the Na+-H+ antiporter.

Bicarbonate (HCO3-) exits the PCT cell through transporter proteins in the basolateral membrane, diffusing into the blood alongside Na+, facilitated by the concentration gradient. This process supports pH balance in the blood.

The reabsorption of solutes in the PCT creates an osmotic gradient, drawing water from the tubular fluid into the interstitial fluid and subsequently into the peritubular capillaries, contributing to the overall reabsorption of water.

The thick ascending limb of the loop of Henle contains Na+-K+-2Cl- symporters in its apical membrane, which actively transport one Na+, one K+, and two Cl- ions from the tubular fluid into the cell.

Na+ pumped into the interstitial fluid from the thick ascending limb cell via active transport diffuses into the vasa recta, a blood vessel network surrounding the loop of Henle.

Cl- exits the cell through leakage channels in the basolateral membrane, moving into the interstitial fluid and then into the vasa recta, following the Na+ transport pathway.

The distal convoluted tubule (DCT) and collecting duct play a vital role in regulating the fine-tuning of electrolyte and water reabsorption, ensuring the body's homeostasis.

Five hormones - aldosterone, atrial natriuretic peptide (ANP), angiotensin II, parathyroid hormone (PTH), and antidiuretic hormone (ADH) - play a crucial role in regulating the reabsorption of Na+, Cl-, Ca2+, and water, as well as the secretion of K+ by the renal tubules, maintaining overall body fluid balance and blood pressure.