Renal Physiology Quiz

A mechanism that keeps the blood flow rate (RBF) and glomerular filtration rate (GFR) relatively stable despite changes in systemic arterial pressure.

This theory suggests that an increase in blood pressure stretches the afferent arteriole, causing it to constrict, thereby reducing renal blood flow and glomerular filtration rate.

The constriction of the afferent arteriole decreases the rate of blood flow into the glomerulus, leading to a lower GFR.

Constriction of the efferent arteriole initially increases GFR by increasing pressure in the glomerulus. However, prolonged constriction can lead to a decrease in GFR due to increased plasma COP.

Mild stimulation of sympathetic nerves causes afferent arteriolar constriction and reduces GFR. Strong stimulation greatly reduces blood flow and pressure in the glomerulus, halting filtration.

An increase in arterial pressure causes the afferent arteriole to automatically constrict, preventing a major rise in glomerular pressure and limiting the increase in GFR.

A portion of plasma fluid is not filtered until new plasma flows into the glomerulus. Increased plasma flow leads to an increased filtration rate.

The pressure inside the glomerulus that drives the filtration process.

A group of specialized cells located at the junction between the afferent arteriole and the distal tubule, playing a key role in regulating blood pressure and GFR.

A decrease in blood pressure leads to reduced blood flow through the kidneys, causing a drop in glomerular filtration rate. This triggers the release of renin from the JGA, initiating a cascade of events that ultimately raise blood pressure.

Renin, an enzyme released from the JGA, splits angiotensinogen into angiotensin I. Angiotensin I is then converted to angiotensin II by angiotensin-converting enzyme (ACE), primarily in the lungs.

A powerful vasoconstrictor that raises blood pressure by constricting blood vessels throughout the body, including the efferent arteriole of the kidney glomerulus.

Angiotensin II constricts the efferent arteriole more than the afferent arteriole. This increases glomerular pressure, which helps maintain GFR despite decreased blood flow.

Angiotensin II stimulates the adrenal glands to release aldosterone, a hormone that promotes sodium reabsorption in the kidneys. This increased sodium reabsorption leads to water retention, further raising blood pressure.

The RAAS plays a critical role in regulating blood pressure by maintaining GFR, promoting sodium and water reabsorption, and increasing blood volume.

The Myogenic mechanism responds to changes in blood pressure directly on the smooth muscle of the afferent arteriole, while the JGA mechanism is triggered by changes in GFR and sodium levels sensed by the macula densa in the JGA.

The process of urine moving from the kidneys to the bladder.

Muscular contractions that push urine down the ureters.

The junction where the ureter meets the bladder, preventing urine from flowing back up.

The bladder's ability to stretch and hold increasing amounts of urine without raising internal pressure.

Muscles that control urine flow from the bladder to the urethra.

The reflex that triggers urination when the bladder fills.

Nerves that control bladder function.

The process of emptying the bladder.

The process of moving substances from the peritubular capillaries, through the interstitial fluid, and into the tubular lumen via the tubular epithelial cells.

The movement of substances like amino acids from the lumen of the proximal tubule into the epithelial cells, using a co-transport mechanism.

The proximal tubule is the primary site for reabsorption and secretion in the nephron, responsible for about 65% of these processes.

The descending limb of the loop of Henle is highly permeable to water, allowing it to move freely by simple diffusion, while being moderately permeable to urea and sodium.

The ascending limb of the loop of Henle is less permeable to water and more permeable to urea.

The thick segment of the loop of Henle and the distal tubule are specialized for the active transport of sodium against its concentration gradient, and actively secrete potassium.

The final concentration of urine occurs in the collecting tubule, with two functional units: the cortical and medullary portions.

The permeability of the collecting tubule to water is regulated by ADH (Antidiuretic Hormone). High ADH levels make the collecting tubule highly permeable to water, while low ADH levels result in minimal water reabsorption.

A decrease in blood pH (acidosis) stimulates increased alveolar ventilation, leading to a drop in blood CO2 (PCO2).

The renal (kidney) system helps restore acid-base balance by secreting H+ into the urine and reabsorbing bicarbonate (HCO3-) into the blood.

A gain of base (OH- or HCO3-) or loss of strong acid in the body's fluids.

The body's respiratory response to metabolic alkalosis. Increased blood pH (alkalemia) causes a decrease in ventilation, leading to a rise in PCO2 (hypercapnia) and bringing the pH back to normal.

The kidneys adjust the excretion of bicarbonate (HCO3-) to help correct metabolic alkalosis. Decreased H+ secretion leads to increased HCO3- excretion, bringing the pH back to normal.

A condition where CO2 excretion by the lungs falls behind CO2 production in the body, resulting in increased blood PCO2 (hypercapnia).

The process by which the kidneys respond to respiratory acidosis. Increased acidity (low pH) stimulates H+ secretion into urine, leading to increased reabsorption of HCO3- into the blood.

A condition where alveolar hyperventilation causes CO2 expiration to exceed CO2 production, resulting in a decrease in blood PCO2.

The metabolic waste product in reptiles and birds, formed in the liver and kidneys from ammonia. Unlike urea in mammals, uric acid is precipitated in the tubules and excreted as a white coagulum in the urine.

The avian renal portal system delivers venous blood from the portal vein directly to the kidney's tubules. This system facilitates the secretion of uric acid.

The process by which water is reabsorbed from the urine in the cloaca, primarily in the colon and cecum due to antiperistaltic movement.

The combination of precipitated uric acid with mucus, giving avian urine its thick, cream color.

The process by which the concentration of urine is regulated by antidiuretic hormone (ADH), affecting both reptilian and mammalian types of nephrons.

Despite the absence of a urinary bladder, the avian urine contains precipitated uric acid that is mixed with mucus, reducing the osmotic pressure and avoiding obligatory water loss.

The nephron type found in birds, which exhibits features similar to both mammalian and reptilian nephrons. It likely evolved to deal with water conservation demands in terrestrial environments.

The major differences between the avian and mammalian urinary system include the presence of a renal portal system, post-renal urine modification, and the absence of a urinary bladder.