Chapter 19 concept questions Flashcards
Ion regulation is a key feature of kidney function. What happens to the resting membrane potential of a neuron if extracellular K+ levels decrease?
hyperpolarizes (becomes more negative)
What happens to the force of cardiac contraction if plasma Ca2+ levels decrease substantially?
Force of contraction decreases.
If net filtration out of glomerular capillaries occurs, then you know that capillary hydrostatic pressure must be (greater than/less than/equal to) capillary colloid osmotic pressure.
greater than
If net reabsorption into peritubular capillaries occurs, then capillary hydrostatic pressure must be (greater than/less than/equal to) the capillary colloid osmotic pressure.
less than
Name one way in which filtration and secretion are alike. Name one way in which they differ.
Alike: both represent movement from ECF into the lumen. Filtration is only into Bowman’s capsule; secretion takes place along the rest of the tubule.
A water molecule enters the renal corpuscle from the blood and ends up in the urine. Name all the anatomical structures that the molecule passes through on its trip to the outside world.
Glomerulus –> Bowman’s capsule –> proximal tubule –> loop of Henle –> distal tubule —> collecting duct –> renal pelvis —> ureter —> urinary bladder —> urethra
What would happen to the body if filtration continued at a normal rate but reabsorption dropped to half the normal rate?
The body would run out of plasma in under an hour.
Why is the osmotic pressure of plasma in efferent arterioles higher than that in afferent arterioles?
Osmotic pressure is higher in efferent arterioles due to same amount of protein in a smaller volume.
If a hypertensive person’s blood pressure is 143/107 mm Hg, and mean arterial
the pulse pressure, what is this person’s mean arterial pressure? What is this person’s GFR according to Figure 19.6b?
Mean arterial pressure is 119 mm Hg and GFR is 180 L/day.
If systemic blood pressure remains constant but the afferent arteriole of a nephron constricts, what happens to renal blood flow and GFR in that nephron?
Renal blood flow and GFR decrease.
A person with cirrhosis of the liver has lower-than-normal levels of plasma proteins and consequently a higher-than-normal GFR. Explain why a decrease in plasma protein concentration causes an increase in GFR.
With fewer plasma proteins, the plasma has lower-than-normal colloid osmotic pressure opposing GFR, so GFR increases.
If plasma creatinine = 1.8 mg/100 mL plasma, urine creatinine = 1.5 mg/mmL urine, and urine volume is 1100 mL in 24 hours, what is the creatinine clearance? What is GFR?
Creatinine
clearance = (1.5mg creatinine/ mL urine x 1.1L urine/day) / 1.8 mg creatinine/100 mL plasma = 92 L/day.
GFR = 92 L/day
