Download Physio HW Unit 4

Unit IV Homework
Bio 12
Saddleback College
Name__________________________
For extra practice:
http://highered.mcgraw-hill.com/sites/0072351136/student_view0/chapter26/chapter_quiz.html
Homework: Osmotic Pressure Problem.
Neatly present all calculations requested below.
You know that plasma is a solution, composed of many different solutes in water (Table 25-2). Most of
those solutes are sodium chloride (0.9g%). But there are also proteins in plasma (Total protein = 7g%), and
albumin accounts for more than half of that protein. So, let’s assume albumin’s concentration in plasma is
4g%.
1) Compute the osmolalities for each substance, albumin and NaCl, in plasma.
Necessary information:
NaCl molecular weight = 58.5 g/mole. The molecule is formed by ionic bonds, and dissociates into 2 ions.
Albumin molecular weight = 70,000g/mole. Albumin is composed of atoms which are covalently bonded,
and do not dissociate.
It is a fact that the osmotic pressure exerted by 1osmolal (1osmole/L) of solute is 19,300 mmHg; (that’s the
same as 1mOsmolal (1mOsmole/L) solute exerting 19.3 mmHg pressure.)
(“mm Hg” is read as “millimeters of mercury” and it is the unit used to express pressures.)
2) Compute the osmotic pressures exerted by each of the substances, albumin and NaCl in plasma.
Which substance is larger? There are more molecules of which substance in plasma? With this
information, which substance exerts the greater osmotic pressure in plasma, NaCl or protein?
“Colloid osmotic pressure” is the term given to the osmotic pressure exerted by protein.
Reference: Guyton Hall, Pg 51-52 and 296-298
1
Renal Glucose Handling Homework
Biology 12
Saddleback College
You know that renal handling of solutes is described by this equation:
Rate of Excretion = Rate of filtration + Rate of secretion – Rate of reabsorption.
(Review lecture material covered in class this week.)
The terminology is new to you, so remember that
• rate of excretion of any solute (s) is also called urinary output, and can be determined by the
equation:
Urinary output (s) = Urine concentration (s) X urine volume produced/minute
• rate of filtration of fluid is also called glomerular filtration rate (GFR)
• rate of filtration of any solute (s) is also called Tubular Load (s) determined by the equation:
Tubular Load (s) = GFR x Plasma concentration of (s)
Background:
As you know, glucose is freely filtered at the glomerulus, and is reabsorbed but not secreted.
Glucose is reabsorbed only in the proximal convoluted tubule, and the method for glucose reabsorption
involves carriers on the luminal membrane. The problem is, all of us only have a limited number of carriers
for glucose, and (as you saw in an early lab this semester on facilitated diffusion (refer to PhysioEx on
transport), if you have limited numbers of carriers, you limit the maximum rate or speed at which you can
move solutes across membranes. This type of transport, therefore, is called “transport maximum limited ”
or “Tm-limited reabsorption”. We see this type of reabsorption for other sugars and amino acids, but not
for other solutes like NaCl. We witness the effects of this rate-limited transport most often when a person
is diabetic, even though there’s absolutely nothing wrong with one’s kidney function! What’s going on?
Well, you need to understand the normal role of insulin first.
Insulin is the hormone released by the pancreatic beta cells when we eat a meal. It is the hormone
the signals our body cells to prepare to take up the glucose, which we’ve just ingested in the form of
carbohydrates, from the circulating blood. Except for neurons, most body cells cannot take up glucose until
they respond to insulin’s signal, because they first have to insert glucose carriers in their surface
membranes for that specific purpose (remember, glucose is not lipid-soluble, so it requires a carrier for
cellular uptake.)When we eat, plasma glucose levels rise, but with insulin, these levels are almost
immediately lowered back to normal. If pancreatic function is normal, no matter how much carbohydrate
you eat, your plasma glucose levels are always around 100mg%.
In diabetes mellitus, people either don’t make insulin or their insulin is ineffective. When these
individuals eat a meal, their plasma glucose levels rise, but do not decrease; consequently their plasma
glucose levels can hit very high levels, double, triple and sometimes seven or eight-fold increases from
normal. We will consider many of the consequences of this later. Right now, let’s consider what happens
in the proximal convoluted tubule.
Step 1: Calculate the tubular load of glucose for each of the following plasma glucose levels, using the
equation given above, and fill in the column of the table titled “Filtered Load of Glucose” with your results.
Then plot each of these points on the graph. Draw a line through these points and label the line. Assume a
GFR of 125 ml/min.
2
Plasma Glucose
concentration (mg/ml)
1
2
3
4
5
6
7
8
9
10
Filtered Load of
Glucose (mg/min)
Glucose reabsorption
rate (mg/min)
Glucose excretion rate
(mg/min)
Step 2: The Tm-limited reabsorption rate for glucose is 320 mg glucose / minute. Any amount of
glucose, up to that maximum, can be completely reabsorbed, but nothing more. Enter the amount of
glucose reabsorbed each minute (glucose reabsorption rate) in the next column. Plot the data points for
reabsorption on the same graph (in another color) and draw a line through these points. Label the line
“reabsorption.” What do you notice about the line? Can you identify the values on the x and y axis where
this line turns? What do these two values represent?
Step 3: Calculate the rate of glucose excretion from the equation provided above. Enter each
value in the column labeled Glucose Excretion Rate. Plot the data points for excretion on the same graph
(in another color) and draw a line through these points. Label the line “excretion.” What do you notice
about the line? Can you identify the values on the x and y axis where this line turns? What do these two
values represent?
3
MEMBRANE TRANSPORT
1.
Use the following information to answer questions A – F. Assume
the cell is permeable to all solutes except protein.
CELL
SOLUTION
10% K+
10% Cl10% Na+
10% Protein
60% Water
15% K+
10% Cl5% Na+
5% Protein
__% Water
A.
B.
C.
D.
E.
F.
Which direction will potassium diffuse? __________________
Which direction will chloride diffuse? ____________________
Which direction will sodium diffuse? ______________________
Which direction will protein diffuse? _____________________
What is the concentration of water inside the cell? __________
What direction will water diffuse? _______________________
2.
Cell A
0.9% NaCl
99.1% H20
S0LUTION A
0.3% NaCl
__% H20
Cell B
0.9% NaCl
99.1% H20
SOLUTION B
Cell C
0.9% NaCl
99.1% H20
SOLUTION C
0.9% NaCl
__% H20
15% NaCl
__% H20
A.
For each solution, determine the % of water.
Solution A = ________ % H20
Solution B = ________ % H20
Solution C = ________ % H20
B.
Indicate if the solution is iso-, hypo-, or hyperosmotic to the cell.
Solution A __________________
Solution B __________________
Solution C __________________
C.
State what changes (crenation or lysis) will occur, if any, to the cells when put into the
above solutions
Cell A __________________________
Cell B __________________________
Cell C __________________________
4
D.
Patients are often administered normal saline solutions. Which of the above solutions is
considered to be a normal saline solution? Why is this concentration the safest solution to
give a patient? (pg 298-299 G&H)
3.
In patients with renal disease, filtrate formation decreases and wastes accumulate in the blood.
Dialysis is a process in which the blood is cleaned and its chemical composition is adjusted to normal
levels. During dialysis, the patient’s blood is passed through dialysis tubing which is permeable only to
selected substances. The tubing is immersed in a solution that differs from the composition of the patients
blood (plasma). As the blood passes through the tubing, wastes and excess ions can diffuse out of the
blood into the surrounding solution. Likewise, substances can also be added to the patient’s blood.
Normal Plasma Values of Selected Solutes
Urea
7-26 mg/dl
Potassium
3.5-5.1 mEq/l
Sodium
136-145 mEq/l
Albumin (protein)
3.2-5.0 g/dl
Bicarbonate
22-26 mEq/l
Hypothetical plasma values in a patient with renal disease
Urea
> 30 mg/dl
Potassium
> 5.5 mEq/l
Sodium
< 130 mEq/l
Albumin
4.5 g/dl
Bicarbonate
< 20 mEq/l
Determine the solute concentration of the solution needed to adjust the patient’s blood to
normal values by determining if the concentration in the solution will be greater than, lesser
than, or equal to the concentration of solutes in the patient’s blood. Remember at the end, you
want your patient’s blood to have the same plasma values as a normal person.
BLOOD IN DIALYSIS TUBING
Urea = > 30 mg/dl
Potassium = > 5.5 mEq/l
Sodium = < 130 mEq/l
Albumin = 4.5 g/dl
For each solute,=indicate
the
Bicarbonate
< 20 mEq/l
SOLUTION
Urea ____________________
Potassium _______________
Sodium __________________
Albumin _________________
Bicarbonate ______________
direction of diffusion (into solution, into blood, or not at all).
Urea ________________________
Potassium ____________________
Sodium ______________________
Albumin _____________________
Bicarbonate __________________
5
Effect of Adding Saline Solution to the Extracellular fluid: calculation of fluid shifts and osmolarities
after infusion of hyperosmotic saline. (G&H pgs 299-301).
Objective: Calculate the sequential effects of infusing different solutions on extracellular and intracellular
fluid volumes and osmolarities.
Problem: A nurse, obtains a saline solution and administers 0.5L of 9% sodium chloride solution into the
EC fluid compartment of a 70kg patient whose initial plasma osmolarity is 280mOsm/L. The nurse
assumes with blind faith that someone else knows the chemistry and that this is what the patient needs.
What would be the intracellular and extracellular fluid volumes and osmolarities after osmotic equilibrium?
Step 1: calculate the initial conditions including the volume, concentration, and total mOsmoles in
each compartment. Assume ECF volume is 20% of body weight and ICF volume is 40% body weight.
(You can go back to your first lab unit when you dealt with body fluid compartments). Remember that one
kg has the volume of one liter.
Volume (L)
EC fluid
IC fluid
Total body fluid
Concentration (mOsm/L)
280
280
280
Total (mOsm)
Next calculate the total mOsmoles added to the ECF in 0.5L of 9% sodium chloride.
o What does 9% represent?
o How many grams would you have in one liter?
o The molecular weight of NaCl is 58.5 grams, so determine the molarity (M/L).
o Knowing the nurse administered only 0.5L, how many moles were administered?
o 1 mole of NaCl is equivalent to 2 osmoles due to dissociation. How many osmoles did the nurse
administer to the patient?
o How many milliosmoles is this?
Step 2: Calculate the instantaneous effect of adding your _______milliosmoles of sodium
chloride to your patient. There would be no change in the ICF concentration or volume, and there would be
no osmotic equilibrium. In the ECF, however, there would be an additional __________ mosmoles of total
solute. Keep in mind your ECF now has an additional 0.5L volume as well. Determine the concentration
by dividing your new total mosmoles in the ECF by your new volume.
EC fluid
IC fluid
Total body fluid
Volume (L)
Concentration (mOsm/L)
Total (mOsm)
b)
280
No equilibrium
a)
6
Step 3: calculate the volumes and concentrations that would occur within a few minutes after osmotic
equilibrium develops. The concentrations in the ICF and ECF compartments would be equal and can be
calculated by dividing the total mOsmoles in the body ____________ (see “a” in your chart above) by the
total volume _________________ of the body (see “b” from your chart above). Your new concentration
_____________will be in all body fluid compartments. Assume no solute or water has been lost form the
body and that there is no movement of NaCl into or out of cells, now calculate the volumes of the ICF and
ECF compartments.
Divide the total mOsmoles of the ICF by the concentration to yield a volume _______________.
Divide the total mOsmoles of the ECF by the concentration to yield a volume ______________.
Fill in your table below:
Volume (L)
Concentration (mOsm/L)
Total (mOsm)
EC fluid
IC fluid
Total body fluid
What has happened to the volume of the body compartments? Which gained? Which lost volume?
So, the question now is, do you have an understanding about osmolarity? What do you think this solution
has done to the patient’s tissues? Lysis? Crenation?
Please repeat this process but now the patient is an extreme athlete who is being encouraged to chug
2L of pure water to re-hydrate. (remember that the transcellular compartment is part of the ECF
volume). Table one stays the same as the previous example, but tables 2 and 3 are different and are
included below for you to fill-in.
Step 2: Calculate the instantaneous effect of adding 2L of pure water to the athlee. There would be no
change in the ICF concentration or volume, and there would be no osmotic equilibrium.
EC fluid
IC fluid
Total body fluid
Volume (L)
Concentration (mOsm/L)
Total (mOsm)
b)
280
No equilibrium
a)
Volume (L)
Concentration (mOsm/L)
Total (mOsm)
EC fluid
IC fluid
Total body fluid
What has happened to the volume of the body compartments? Which gained? Which lost volume?
7
Below is the picture of a nephron that will be used on your upcoming lecture exam. Make sure you
understand what each arrow is pointing to. Be ready to match statements to the picture.
Matching: Below is a picture of a nephron. Choose the best portion of the nephron that matches the
descriptions below and mark them on your scantron. Answers may be used more than once.
First: Identify what each label is pointing to and then answer the following descriptions:
This site is only permeable to ions.
This site has the Na+/K+/2Cl- transporter.
Site of water reabsorption, ions, glucose and amino acids.
Site of highest capillary hydrostatic pressure.
Site of highest capillary colloid osmotic pressure.
This is a functional contact between the Distal convoluted tubule and the afferent and efferent arterioles.
This is just a sample, you should expect MANY more of these types of questions.
AC
.
AB
.
E.
D
.
AD.
A. None of the
options are
correct
C.
BD
.
B.
BC.
8
Solving Acid Base Problems, Arterial Blood Gases
Read article “Interpreting Arterial Blood Gases”
The typical exam problem you’ll be solving will only provide you with the arterial blood values of paCO2
and [HCO3-], but not pH.
You will have to determine 4 things:
a) pH
b) if this is acidosis or alkalosis
c) the specific acid base imbalance, that is, whether it is respiratory or metabolic in nature
d) whether compensation has begun, and if so, explain specifically what the compensation is.
Here is the way to approach these problems. Let’s use this example:
Given:
paCO2
[HCO3-]
38 torr
20 mEq/L
Steps:
1. Use the HH Equation and determine patient’s pH and simple acid-base state. Do this by looking at
the pH value you get after applying the HH equation. Anything above 7.40 is alkalosis; anything
below 7.40 is acidosis; anything at 7.40 is normal
Example: pH 7.34, this is acidosis
2. Apply the user definition of acid or base state. Memorize these definitions. These are key to
solving the problem!
 Acidosis is the result of either too much plasma acid (CO2) OR too little base (HCO3-)
 Alkalosis is the result of either too much plasma base (HCO3-) OR too little acid (CO2)
Example: this case of acidosis is caused by either too much acid (CO2) OR too little base (HCO3-) in
body tissues
3. Is this respiratory or metabolic? Compare each actual arterial blood value to its normal value.
Determine which one of the two values “fits the definition of the acid base state” you gave in the
last step. This will allow you to identify which value is the cause of the imbalance in pH.


If the paCO2 value fits the definition, then conclude that the problem is “respiratory” since CO2
is handled by the respiratory system.
If the [HCO3-] value fits the definition, then conclude that the problem is “metabolic” since
HCO3- is handled by the renal system.
Example:
HCO3- (mEq/L)
paCO2 (torr)
Normal value
24
40
Actual value
20
38
9
Here, both values are below normal. We have too little plasma acid (CO2) and too little base
(HCO3-) in this person. Too little base (HCO3-) “fits” the definition of acidosis therefore, so it is
the cause of the acidosis in this patient. Since the blood level of (HCO3-) is handled by the kidney
rather than the respiratory system, this is metabolic acidosis.
4. Has compensation begun? Notice that renal compensation is not always immediate, it takes a while.
Here’s how to know: Whichever value you picked for the “cause” of the imbalance, the other value
will reflect the compensation, if there is any.


If the value is normal, it indicates that compensation has not yet begun.
If the value is different from normal, it reflects compensation. Notice the value will change
in the direction to correct the problem – lowering or raising the acid or base in blood, which
helps to bring pH closer to normal.
Example: the pCO2 value reflects the compensation. It is 38 torr, lower than normal.
Compensation has begun in this patient.
Now, explain how each system compensates.
a. Renal system: discuss filtration, reabsorption and excretion mechanisms for HCO3- .
b. Respiratory system: discuss chemoreceptors and respiratory reflex loop producing hypo-,
normo- or hyperventilation.
Do not forget that both renal and respiratory systems compensate in metabolic problems, and
only one system (renal) compensates in respiratory problems.
Example: The respiratory system is removing CO2 faster than cells are producing it. This is
called hyperventilation. The chemoreceptors sense low pH which triggers increase
ventilatory rates to “excrete acid” from plasma. Go to your lecture notes and text to describe
this neural reflex.
Since this condition is metabolic, the renal system will also compensate. It will not only
reabsorb all filtered bicarbonate, but it will also make and reabsorb “newly formed”
bicarbonate. Go through your lecture notes and text to learn how this occurs at the cellular
level in the nephron.
10
Acid Base Worksheet
Blood pH is a variable that is maintained at a setpoint of pH 7.40 by homeostatic mechanisms. When there are
respiratory or metabolic changes in the body we rely on intracellular and extracellular buffers, along with the renal
and respiratory systems to maintain setpoint. And when one of these systems is compromised, we depend on the
remaining systems to compensate.
Recall that in negative feedback, the size of the correction is related to the size of the deviation. As blood pH
deviates from 7.40, even with the presence of buffers, renal handling of bicarbonate and respiratory ventilation
changes will kick in to attempt to restore pH (compensate). But as deviation (blood pH) approaches setpoint (7.40),
the compensation decreases, so pH never quite reaches septoint. How large is compensation if pH actually is at
setpoint?
In some of these problems, you will see an “early” and “late” set of blood values. Examine these alongside your
calculated pH values. This will give you an opportunity to see how physiological compensation attempts to bring the
pH back toward setpoint, but rarely or never back to the setpoint.
Read the article on Arterial Blood Gases recommended in lecture before beginning these problems. The method
explained in this article will help to give you a better understanding of how to think through these problems.
1. Suppose a person had the general malaise that is diagnosed as “acidosis.” The person is showing
clinical signs of nervous system depression and unresponsiveness. The following blood gas values
were obtained at two different time intervals:
AT DIAGNOSIS:
PaCO2 = 70.5 mm Hg / HCO3- = 28 mEq /L
LATER:
PaCO2 = 69 mm Hg / HCO3- = 39 mEq/L
a) Use the Henderson-Hasselbach Equation to calculate the pH value at both times. Show
your work:
b) Using the method described in the ABG article, identify the specific acidosis condition.
Explain your reasons.
c) Explain the physiological basis of the problem and the “extra” bicarbonate ion in the
compensation.
2. Suppose a person was hyperventilating and showing clinical signs of alkalosis (tetany.) The
following lab values were obtained:
HCO3- = 20 mEq/L
PaCO2 = 16 mm Hg
a) Calculate the pH value and identify the specific condition.
b) Explain both the renal and/or respiratory compensation mechanisms.
11
3. Suppose a person with a Giardia infection becomes stuporous and shows signs of hyperventilating.
Lab values show:
AT DIAGNOSIS:
PaCO2 = 33 mm Hg / HCO3- = 10 mEq/L
LATER:
PaCO2 = 28 mm Hg / HCO3- = 15 mEq/L
a) Calculate both pH values
b) Identify the specific acid/base condition
c) Explain the physiological basis for the problem and the compensation.
4. Suppose a person ingests a large amount of baking soda for stomach upset. The individual shows
signs of irritability. Lab values:
AT DIAGNOSIS:
LATER:
PaCO2 = 33 mm Hg / HCO3- = 40 mEq/L
PaCO2 = 43 mm Hg / HCO3- = 30 mEq/L
a) Calculate both pH values
b) Identify the specific acid/base condition
c) Explain the physiological basis for the problem and the compensation
Additional acid/base problems (for your own practice). For each, go through the same steps you
did above: determine pH, give the specific condition, and explain what compensation must occur,
or must already be occurring to correct the pH.
a) PaCO2 = 48 mm Hg / HCO3- = 32 mEq/L
b) PaCO2 = 34 mm Hg / HCO3- = 18 mEq/L
c) PaCO2 = 30 mm Hg / HCO3- = 26 mEq/L
d) PaCO2 = 52 mm Hg / HCO3- = 26 mEq/L
12
Study questions:
 Be ready to calculate pH using the HCO3-/ CO2 Henderson-Hasselbach equation. Write it here.
What is the purpose of the “0.03” in the denominator?
 Recognize that pH imbalances affect excitability of excitable cell membranes (muscle and nerve.)
What are the general clinical signs of alkalosis? Of acidosis?
 Be able to determine if a patient is acidotic or alkalotic. Be able to determine what system caused
the change in pH and which system or systems is/are compensating. Can you explain how
compensation occurs at the cellular level?
 At the level of the renal tubule, show the cellular process of maintaining plasma levels of
bicarbonate by reabsorption or the process of forming “new” bicarbonate. Why do we need
carbonic anhydrase at these particular regions of the nephron?
 When can the renal system compensate for acid-base shifts? When can the respiratory system
compensate for acid-base shifts?
13
Acid/Base Practice
Look over the equations below. Associate each one with an acid-base condition (I would write the specific
condition in the box to help you stay focused). Then read the descriptions below, and match the one best
equation (A-D) with its description. Use the information from your lecture to help you with this.
A) pH = HCO3 (p)
paCO2 (c)
B) pH = HCO3 (p)
paCO2 (c)
C) pH = HCO3 (c) D) pH = HCO3 (c)
paCO2 (p)
paCO2 (p)
where (p) = problem AND (c) = compensation
1. Ascent to high altitudes
10. Restrictive, obstructive lung disease
2. ingestion, infusion or production of
fixed acids
11. Hyperventilation syndrome
3. Decreased excretion of acid by kidney
12. Overventilation on mechanical respirators
4. Loss of bicarbonate from ECF
13. diabetic ketoacidosis
5. Salicylate overdose (aspirin)
14. Excessive loss of fixed acids due to
ingestion, infusion, or renal reabsorption of
bases
6. Diarrhea (loss of intestinal HCO3-)
15. Loss of gastric juice during vomiting
7. Accumulation of lactic acid in severe
hypoxia
16. Intake of stomach antacids
8. Depression of respiratory centers via
narcotic, drugs, anesthetics, trauma
17. Diuretic therapy (loss of H+ ions)
18. Severe potassium depletion
9. Interference with respiratory muscles by
disease, drugs, toxins
14
A Case of Diabetes Insipidus
by
David F. Dean
Department of Biology
Spring Hill College
Copyright © 1999–2007 by the National Center
for Case Study Teaching in Science, University
at Buffalo, State University of New York
Modified by K. Street
Case Presentation
Amanda Richards is a 20-year-old junior in college. She is majoring in biology and hopes someday to be a
pediatrician. Beginning about a month ago, Amanda noticed that she was waking up once, sometimes twice
a night, by the need to go to the bathroom. More recently, she has noticed that she needs to go to the
bathroom during her school day much more frequently than before, sometimes as often as once every hour.
At first Amanda thought that her increased frequency of urination was due to the coffee she drank, but
when she reduced her coffee consumption to one cup in the morning, she still needed to go to the bathroom
just as often. In addition, Amanda was buying bottled water by the case, and she found herself never
without a beverage in her hand or nearby. She also noticed that her urine seemed pale and colorless.
When Amanda told her mother of her problem, her mother became very concerned and arranged for
Amanda to see the family physician. Her physician found no abnormalities on physical examination.
However, a blood chemistry profile revealed Amanda’s plasma sodium level to be 149 mEq/L, plasma
osmolarity was 308 mOsm/L, and her fasting plasma glucose was 85 mg/dl. An analysis of Amanda’s urine
showed a urine osmolarity of 200 mOsm/L. The urine sample was negative for the presence of glucose.
An extensive history revealed that no other member of the family had ever displayed Amanda’s symptoms.
Amanda had no history of traumatic head injury and an MRI of her brain was normal.
Next, a two-hour water deprivation test was performed on Amanda. After two hours of not being able to
drink water, the osmolarity of her plasma and urine were measured a second time. This time her urine
osmolarity was unchanged; however, the osmolarity of her plasma increased to 315 mOsm/L. She was then
injected with a drug called DDAVP. One hour after the injection, the osmolarity of her plasma decreased to
290 mOsm/L and the osmolarity of her urine increased to 425 mOsm/L.
Based upon the results above, Amanda’s medical history, and the results of the MRI, a diagnosis of
idiopathic pituitary diabetes insipidus was made.
15
Questions
1. Describe the mechanism by which normal fluid regulation in the body occurs.
2. What is considered to be excessive thirst and urination in an adult?
3. List and briefly describe the types of diabetes insipidus.
4. How is pituitary diabetes insipidus diagnosed?
5. In what ways is diabetes insipidus similar to diabetes mellitus? In what ways do they differ?
6. How does the mechanism by which diuresis occurs with diabetes insipidus differ from that which
occurs in diabetes mellitus?
7. How does diabetes insipidus compare with a condition called syndrome of inappropriate antidiuretic hormone (SIADH)?
8. What is DDAVP and how is it administered?
9. Why should a person who has pituitary diabetes insipidus and does not feel unreasonably
inconvenienced by the symptoms take treatment?
10. Why is ADH also known as vasopressin?
16
Red blood cell
Plasma protein
E
Filtered solute
A
This is a picture of the glomerulus and Bowman’s capsule.
1. In a healthy person what is the colloid pressure in Bowman’s capsule?
2. When can this change and actually reduce GFR?
3. If GFR decreases, what happens to tubular load for any substance?
4. If GFR decreases what happens to the clearance of any substance?
5. Exactly how can the hydrostatic pressure in the glomerulus be altered?
6. What is Kf? Does this change over a lifetime?
7. What generally inhibits plasma proteins from being filtered?
17
This is a picture of the proximal convoluted tubule.
The proteins on the basolateral sides are Na+/K+ ATPase molecules and the proteins on the apical side are
cotransporters.
The red tubes alongside the PCT represent the peritubular capillary bed.
1. How much filtered sodium is reabsorbed here?
2. How much glucose that was filtered gets reabsorbed here? (assuming no breach of Tmax for
glucose transporters)
3. How much of the amino acids that were filtered gets reabsorbed here?
4. Name one diuretic that works here:
5. Exactly how do osmotic diuretics work?
6. If a patient has Diabetes mellitus, would all of the glucose that was filtered be reabsorbed? Why?
7. Continuing with the above question, what would happen with the water reabsorption in this region?
8. What is the osmolality of the solution in this region compared to plasma?
9. How is water reabsorbed along this region? What solute most directly affects its reabsorption?
10. How is sodium reabsorbed along this region? (Be very specific!)
11. What is plasma renal threshold?
18
Cell three
Cell 2
Cell 1
The picture above shows and expanded region of the proximal convoluted tubule
Take time to draw the following:
The sodium/potassium ATPase.
What is this pump doing to the internal (cellular) gradients for potassium and sodium?
Draw on the apical membrane (using cell one) how glucose and amino acids are reabsorbed.
Draw (using cell 3) how hydrogen is secreted here and how most of the bicarbonate is reabsorbed from this
region.
How does acetazolamide work in this region? If abused, could it cause an acid/base imbalance? If so, what
type and why?
Draw how chloride is reabsorbed from this region.
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This picture represents the loop of Henle (thin descending, tip, thin ascending and thick ascending).
Draw the peritubular capillary bed around it.
Which region is impermeable to water and reabsorbs salts? Is a hormone needed to do this?
Where would the tubular fluid be maximally hyperosmotic to plasma? Is a hormone needed to do this?
Where is the tubule permeable to water and only slightly permeable to salt? Is a hormone needed to do
this?
Where would furosemide have action? Exactly how does furosemide work as a diuretic?
Where is the Na+/ K+/ 2 Cl- transporter found?
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This is a picture of the early and distal convoluted tubule. (A fictitious line is drawn here to separate the
two).
1. Where would the macula densa be found? What do they do and how would GFR be altered?
2. Which region is impermeable to water and reabsorbs salts but not hormonally sensitive?
3. Which region can make a very steep bicarbonate gradient (i.e., make new bicarbonate?) Which
cells do this?
4. Where does hormonally regulated potassium secretion occur? What hormone does this?
5. What segment is called the “diluting” segment because it continues to reabsorb salt and not water.
Is it hormonally sensitive?
6. What diuretics can work here (the part to the left of the line)? Does it affect potassium in any way?
7. What diuretics can work on the segment to the right of the line? Do they affect potassium levels?
8. Which region would be part of the juxtaglomerular apparatus?
9. What part of the juxtaglomerular apparatus detects a drop in blood pressure and releases renin?
10. What happens with the release of renin? (Be specific and take your answer all the way until there is
compensation).
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Cell three
Cell 2
Cell 1
This picture now shows the collecting duct cells.
1. Is this structure hormonally sensitive? If yes, to which hormone?
2. What happens when this hormone binds to the receptor on these target cells?
3. What happens to the filtrate? What happens to the concentration and volume of the urine when
levels of this hormone are high?
4. Explain why there is diuresis in a person with nephrogenic diabetes insipidus (use this picture if
necessary).
5. If ADH levels are very high, what determines the minimal volume of obligatory water loss?
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