Download Homework Assignment 3

Renal Physiology
1. What are the functions of the renal system?
2. Describe the anatomy of the urinary system, including the microanatomy of the
nephronic tubule.
3. Describe the three basic processes and how they interact to form urine. Define the
difference between secretion and excretion.
4. Discuss the forces involved in glomerular filtration. What is the average GFR and
how is it regulated?
5. Distinguish between active and passive reabsorption and describe all the tubular
transport processes that are linked to the Na+/K+ ATPase.
6. Describe sodium regulation in the body.
7. Describe water regulation in the body.
8. How is the medullary osmotic gradient produced and what is its major function?
9. Describe K+ regulation in the body
10. Describe Ca2+ regulation in the body
11. What is the filtered load of sodium if inulin clearance is 125 ml/min and the sodium
concentration in plasma is 145 mM?
12. Calculate the rate of urine production, given that the inulin clearance is 125 ml/min
and the urine and plasma concentrations of inulin are 300 mg/liter and 3 mg/liter,
respectively.
13. If the urine concentration of a substance is 7.5 mg/ml of urine, its plasma
concentration is 0.2 mg/ml of plasma, and the urine flow rate is 2 ml/min, what is the
clearance rate of the substance? Is the substance being reabsorbed or secreted by the
kidneys?
14. Predict the changes (increase/decrease/no change) that will be present in the
following parameters as a consequence of a pathological condition that results only in
a leaky glomerulus (permeable to plasma proteins), explain your answer.
a.
b.
c.
d.
plasma protein concentration
plasma colloid osmotic pressure
total body sodium
plasma volume
e. interstitial fluid volume
15. Predict the changes (increase/decrease/no change) that will occur in the following
parameters when plasma volume decreases, explain your answer.
a. mean arterial pressure
b. glomerular filtration rate
c. renal blood flow
d. plasma rennin concentration
e. plasma aldosterone concentration
f. Na excretion
g. Vasopressin secretion
16. Use the following data to answer the questions below:
Plasma inulin concentration = 0.01 mg/ml
Urine inulin concentration = 1.00 mg/ml
Urine flow rate = 1.20 ml/min
Plasma concentration of solute x = 0.05 mg/ml
Urine concentration of solute x = 2.00 mg/ml
Plasma PAH concentration = 0.001 mg/ml
Urine PAH concentration = 0.390 mg/ml
Hematocrit = 0.50
Calculate:
a) GFR
b) Whether there is net reabsorption or net secretion (or neither) of solute x.
c) Filtered Load of X
d) Renal blood flow
17. The human kidney can produce a maximal urine osmotic concentration of about 1400 mOsm, an
impressive feat but poor in comparison to some desert mammals. Knowing what you do about the
concentrating mechanism (or what you can learn by studying the text), how might our kidneys be altered,
either functionally or anatomically, to improve our concentrating performance?
1. List and indicate the functions of each of the body’s chemical buffer systems
2. Describe the three lines of defense against changes in [H+] in terms of mechanisms
3. What are the causes of the four categories of acid-base imbalances and what
compensation does the body affect for each.
4. Describe the actions of the kidney that lead to H+ secretion and HCO3- reabsorption.
5. Of what importance is PO43- and NH3?
6. How do the kidney’s produce ‘new’ HCO3-?
7. Death occurs if the plasma pH falls outside the range of 6.8 to 8.0 for an extended
time. What is the concentration range of H+ represented by this pH range?
8. Given an αCO2 = 0.03 mM/mmHg, a normal pH of 7.4, a normal [HCO3-] of 25 mM,
and a normal PCO2 of 40 mmHg; How much would the PCO2 have to change to
produce a pH of 6.8 (assume only a respiratory change)? How much would the
[HCO3-] have to change to produce the same pH change (assume only non-respiratory
change)?