Exam three practice questions

Question 1

Na can be passively reabsorbed at the

Answer 1

thin portion of the ascending loop of henle

Question 2

Conducting arteries

Answer 2

elastic arteries, responsible for absorbing the shock of arterial BP, pulsating

Question 3

distributing arteries

Answer 3

muscular arteries, responsible for vasoconstriction/vasodilation

Question 4

Bohr or Haldane?

conditions that favor the unloading of O2 at tissues, hi H+, hi CO2

Answer 4

BOHR

Question 5

What is the chloride shift at the tissues?

Answer 5

CO2 at the tissues enters the RBC and quickly converts to H2CO3 in presence of carbonic anhydrase. However, this is an acid that readily dissociates to H+ and HCO3-. The H+ binds to subunits on the Hb, stabilizing the T state and causing the unloading of O2 (Bohr effect). The HCO3- leaks back out to the plasma in exchange for Cl- in. This is called the chloride shift.

Question 6

What is the chloride shift at the lungs?

Answer 6

Hi pO2 causes O2 to diffuse from the alveoli to the alveolar capillary juxtaposed to it. O2 binding HHb causes the H+ to dissociate from the Hb. H+ goes and finds a HCO3- that has come back into the RBC via a chloride shift (Cl- exits as HCO3- enters). H2CO3 is formed, which carbonic anhydrase rapidly converts to HOH and CO2. CO2, being a gas, diffuses out to the alveoli.

Question 7

What constitutes the Juxtaglomerular Apparatus?

Answer 7

1. juxtaglomerular cells - modified smooth muscle cells around the afferent arteriole. Secrete renin.
2. macula densa - specialized epithelial cells around the ascending loop of Henle. Have chemoreceptors that measure filtrate concentration. If [filtrate] is too high, then the GFR is too high. Causes vasoconstriction of afferent arteriole, lowering glomerular BP, giving more time for reabsorption. If [filtrate] is too high, causes vasodilation of afferent arteriole, giving less time for reabsorption.
3. mesangial cells - means of communication between MD and JC

Question 8

Normal expiration occurs because

Answer 8

a subset of VRG neurons (expiratory neurons) send inhibitory impulses to the excitatory VRG neurons (inspiratory neurons) to stop their firing and sending impulses to the diaphragm and the external intercostals

Question 9

What is the normal clearance for healthy kidney functioning?

Answer 9

C=125 mL/min, creatinine is like a natural inulin

Question 10

PAH should equal…

Answer 10

625 mg PAH /625 mL plasma, frelly filtered AND secreted

Question 11

At what partial pressure does a decrease in O2 causes physiological problems?

Answer 11

p50 for O2 is about 30 torr, and p75 is 40 torr, so 70 torr would have a hi pO2

Question 12

What is the immenent treatment for low blood pressure?

Answer 12

increase venous return! If venous return is lessened, HR and SV will decrease, initiating the death spiral.

Question 13

Sodium reabsorption

Answer 13

most actively reabsorbed at PCT, actively reabsorbed at ALOH, Aldosterone controls at DCT, and passive reabsorption at thin ALOH

Question 14

Where are the symport pumps in the PCT?

Answer 14

Na/glucose symport is on the apical side

Question 15

Where are the antiport pumps

Answer 15

Na/K antiport (Na to interstitium) on the basolateral side

Question 16

Solutes are reabsorbed at the PCT by

Answer 16

active transport of the those solutes

Question 17

When K is inhibited from being secreted into the renal filtrate…

Answer 17

urine volume can increase

Why? Na+ is not being reabsorbed, and water follows salt.

Question 18

When there is increased preload…

Answer 18

the stretching of the atrial cells irritates the SA node making it depolarize more quickly

Question 19

Transport maximum mechanism limits indicate

Answer 19

there are threshold amounts of specific solutes that symport pumps can clear from the filtrate

Question 20

Is Lasix a K-sparing diuretic?

Answer 20

no, lasix is just a loop diuretic that prevents solutes from being actively reabsorbed in the ascending loop of henle. However, this serves a dual purpose because the interstitium will have less of an osmotic gradient which would pull water out in the descending loop of henle.

Question 21

K-sparing diuretics…

Answer 21

dont keep all K from being lost to the urine. Loop diuretics like Lasix inhibit ANY reabsorption of solutes back to the interstitium, including K. They only inhibit the active secretion of K in exchange for Na by the work of aldosterone. This aldosterone inhibitors are ALDACTONE. A K supplement may be given even with K-sparing diuretic. Na+ reabsorbtion blocker and K-sparing diuretics can be in one medication because the former inhibits reabsorption and the latter inhibits secretion of K. An example of this would be Dyazide.

Question 22

GFR can be determined by…

Answer 22

levels of creatinine in the urine

Question 23

What is the clearance value if a substance is freely filtered and not reabsorbed or secreted?

Answer 23

125 ml/min

Anything greater than this means that the substance is being secreted as well.

Anything less than this mean the substance is being reabsorbed.

Question 24

Solutes are reabsorbed at the PCT by

Answer 24

simple diffusion

Question 25

Osmotrol/mannitol increases osmolality of…blood or filtrate?

Answer 25

filtrate, increases urine production/ same mechanism as diabetics having to pee a lot