Urination Vocab

Diuretic

Compound that increases urine volume

Caffeine

Diuretic that promoted vasodilation in the nephron, increasing GFR

Alcohol

Diuretic that inhibits ADH release from the posterior pituitary, causing less water recovery in the collecting duct and an increased GFR

Hydrochlorothiazide

Anti-hypertensive diuretic that inhibits the Na/Cl symporter in the DCT and collecting duct, resulting in a loss of sodium and water

Countercurrent multiplier system

As the ascending loop actively transports Na+ and Cl- out of the tubular fluid, the interstitial osmolarity in the medulla increases, drawing water out of the descending loop and into the vasa recta; functions due to parallel loop limbs

Urea

Produced from ammonia detoxification during protein metabolism in the liver and used by the kidneys to maintain an osmotic gradient

Urea recycling

Diffusion of urea out of the collecting ducts into the deep medulla and then into the ascending loop; contributes to high osmolarity in the deep medulla, which is crucial for water reabsorption

Sodium

Electrolyte that plays the largest role in the osmolality of the plasma; has a strong osmotic effect that attracts water

-Excess = high blood pressure, heart attacks, edema, strokes

Calcium

Electrolyte necessary for muscle contraction, nerve transmission, and blood clotting; regulated by parathyroid hormone

Potassium

Electrolyte necessary for nerve conduction, skeletal muscle function, and cardiac contraction and rhythm

Ureterovesical valve

Physiological sphincter that allows urine into the bladder and prevents reflux of urine from the bladder bac into the urine

Physiological sphincter

Sphincter that does not have a distinct ring of muscle tissue and functions instead through the cumulative actions of different muscles or tissue that create a sphincter-like effect

Vesicoureteral reflux

Urine moves backwards from the bladder to the kidneys, greatly increasing the risk of serious UTI

Detrusor muscle

Irregular crisscrossing bands of smooth muscle in the bladder wall

Internal urethral sphincter

Involuntarily controlled smooth muscle that rings around bladder neck

External urethral sphincter

Voluntarily controlled skeletal muscle that surrounds urethra distally

Micturition

Urination resulting from an interplay of involuntary and voluntary actions by the internal and external urethral sphincters

Incontinence

As bladder volume approaches maximum capacity, voluntary constraint fails

Urine storage reflex

Governed by the sympathetic nervous system to keep urethral sphincters contracted and the detrusor muscle relaxed while the bladder fills with urine

Pontine storage center

Cluster of neurons in the pons that maintains external urethral sphincter tone and enhances sympathetic activity during bladder filling

Urine voiding reflex

Once the bladder reaches a certain level of distension, sensory signals are sent to the brain to initiate the urge to urinate; primarily coordinated by the parasympathetic nervous system

Pontine micturition center

Cluster of neurons in the pons that initiates and coordinates the voiding reflex; promotes parasympathetic system, inhibits sympathetic system, and reduces somatic nerve system signaling to external urethral sphincter