Urine moves down each ureter toward the bladder by waves of smooth muscle contraction called peristalsis.
Missing Word
peristalsis
Peristalsis is a wave of smooth muscle contraction that pushes contents along a tube. In the ureters it moves urine toward the bladder regardless of body position.
Category: Urine Transport
Question 2
The tube that carries urine from the bladder to the outside of the body is the urethra.
Missing Word
urethra
The urethra is the final passage of the urinary tract, running from the bladder neck to the external opening. It is distinct from the ureters, which drain the kidneys.
Category: Urine Transport
Question 3
The smooth triangular area on the floor of the bladder, outlined by the openings of the two ureters and the urethral opening, is the trigone.
Missing Word
trigone
The trigone is the triangular region of the bladder floor marked by the two ureteral openings and the urethral opening. Its smooth surface does not form folds as the bladder empties.
Category: Urine Transport
Question 4
In males, the urine passageway just below the bladder runs through the prostate gland.
Missing Word
prostate
The prostate gland surrounds the first portion of the male urethra just below the bladder. Enlargement of the prostate can squeeze this passage and slow urine flow.
Category: Urine Transport
Question 5
The most abundant nitrogenous waste in urine is urea, which the liver makes from ammonia.
Missing Word
urea
Urea forms in the liver when ammonia from amino acid breakdown is combined with carbon dioxide. It is the main nitrogenous waste the kidneys excrete.
Category: Urine Composition
Question 6
Creatinine is a waste product released at a steady rate as muscle breaks down its stored high-energy phosphate compound.
Missing Word
Creatinine
Creatinine comes from the breakdown of creatine phosphate in skeletal muscle. Because it is produced steadily and is filtered by the kidneys, its blood level is used to assess kidney function.
Category: Urine Composition
Question 7
The presence of red blood cells in the urine is called hematuria.
Missing Word
hematuria
Hematuria means blood in the urine. Red blood cells are normally too large to pass the filtration membrane, so their presence suggests bleeding or damage somewhere in the urinary tract.
Category: Urine Composition
Question 8
The tuft of capillaries enclosed by Bowman's capsule, where blood plasma is filtered, is the glomerulus.
Missing Word
glomerulus
The glomerulus is the capillary tuft of the renal corpuscle. Its fenestrated capillaries let water and small solutes pass into the capsular space as filtrate.
Category: Nephron Structure
Question 9
The microscopic functional unit of the kidney, made of a renal corpuscle and a renal tubule, is the nephron.
Missing Word
nephron
The nephron is the structural and functional unit that filters blood and processes the filtrate into urine. Each kidney contains a very large number of them.
Category: Nephron Structure
Question 10
When blood pressure in the afferent arteriole falls, juxtaglomerular cells release the enzyme renin, which cleaves angiotensinogen.
Missing Word
renin
Renin is an enzyme released by juxtaglomerular cells. It converts angiotensinogen into angiotensin I, starting the cascade that raises blood pressure.
Category: Renal Regulation
Question 11
The ability of the kidney to keep its filtration rate fairly steady despite changes in systemic blood pressure is called autoregulation.
Missing Word
autoregulation
Autoregulation is the kidney's built-in control of its own blood flow and filtration, carried out by the myogenic mechanism and tubuloglomerular feedback.
Category: Renal Regulation
Question 12
The kidneys complete the activation of vitamin D by converting it into the hormone calcitriol.
Missing Word
calcitriol
Calcitriol is the active form of vitamin D. The kidneys perform the final activation step, and calcitriol then increases calcium absorption from the small intestine.
Category: Renal Regulation
Question 13
Osmoreceptors in the hypothalamus detect a rise in blood osmolality and trigger the release of antidiuretic hormone.
Missing Word
hypothalamus
The hypothalamus contains osmoreceptors and the neurons that make ADH. When blood becomes too concentrated, these neurons release ADH from their endings in the posterior pituitary.
Category: Fluid and pH Balance
Question 14
A drug that increases urine output, such as one that blocks sodium reabsorption in the renal tubule, is called a diuretic.
Missing Word
diuretic
A diuretic is any substance that increases urine volume. Many work by blocking sodium reabsorption so that water stays in the filtrate with the sodium.
Category: Fluid and pH Balance
Question 15
The kidneys help correct acidosis by reabsorbing and producing bicarbonate ions, the main base buffer in blood plasma.
Missing Word
bicarbonate
Bicarbonate is the chief buffer base of the blood. The kidneys reclaim filtered bicarbonate and generate new bicarbonate while secreting hydrogen ions, which raises blood pH.
Category: Fluid and pH Balance