Acid/Base Lab: Question 1 part D

There isn't really one resource to find the answer, you just have to figure it out on your own. If you answer the hint questions below, you should be able to figure it out:

How does insulin work? What happens to blood glucose levels when you inject insulin?

Note that the problem states a "big" shot of insulin. If you give too much insulin what would happen to the blood glucose? And finally, what vital organ is extremely dependent on blood glucose?

Acid/base homework questions clarification

Hello again!

Here are the homework questions with a little more detail so they won't be so vague. This is just to help you understand the questions, please refer to the original blue sheet when writing up your answers.

For each patient you have four questions that you need to answer:

A. What is his/her exact acid-base diagnosis?

The answer for this is the first diagnosis you found. You need to answer with only two words: respiratory or metabolic acidosis or alkalosis.

B. How did his/her medical diagnoses lead to the acid-base disturbance? (Or a variation of this question) For this question you need to state the medical diagnosis (the second one you found in lab). For example, this would be diabetes mellitus, pulmonary edema, etc. Then you need to explain IN DETAIL exactly how this medical condition caused the acid/base imbalance stated in question A above. BE AS DETAILED AS POSSIBLE.

For 1B, make sure you tell me exactly how the little girl's medical condition resulted in the acid/base imbalance you stated in question 1A. Tell me exactly which acid was causing the trouble, where it came from, and why it was building up in her system.

For 2B, tell me exactly how the acid/base disturbance came about because of his medical condition. 

For 3B, make sure you tell me how his medical condition led to his acid/base balance. You may want to look up the uses of the drug involved, but all the info you need is already in your lab book.

For 4B, make sure you tell me the source of each acid (there is more than one) involved and why her medical condition caused a change in each type of acid. Again, any information about the drugs involved is in your lab book.

C. Is he/she compensating? How do you know? (Use symptoms, not the graph)

For this question, you need to go back to look at the symptoms presented by the patient in the beginning of the exercise. State what the compensating mechanism should be (respiratory or metabolic acidosis or alkalosis) and what observable symptom the patient has that is producing the compensatory mechanism.

Don't forget part D on question number 1!

Email me if you still need clarification about the questions, or you need help to answer them. These are due in 2 weeks.

No lab next week! Happy Thanksgiving! 

More frog heart

See diagram in Silverthorn, page 500 for question 1. This will help explain effects on heart rate.


Use external resources for the caffeine question. I'm not going to be too strict on this part since it seems Dr. Rechs didn't cover this in lecture. Basically caffeine blocks adenosine receptors, thus enhancing the activity of NorEp. Use this as a starting point.

Frog heart question #2

For the dark purple heart, I'll give you some hints.

1. What specifically makes blood change color (any type of blood, not just frog blood).

2. What was happening to the heart at the time which would result in the blood color change? Remember that the oxygen consumption of the frog's body does not change during the experiment.

Frog heart question #1

Question number 1:


I want you to mention something about hyperpolarization/depolarization of the cell membrane and the ease of achieving an action potential. 


You also need to explain exactly what is happening in the muscle of the heart itself (why you get increased or decreased contractility, etc).

Skeletal Muscle graph

For your graph, use your data from page 60 of your lab manual.

Skeletal Muscle graph

Here is an example of what your graph could look like: 

(These numbers are completely made up, yours will look different!)

Other formats are acceptable as well. To make the one above, I used "XY Scatter" in Excel. Try playing around with Excel and if you can't figure it out, shoot me an email. Hand drawing a graph on graph paper is also acceptable.

Remember to label the X and Y axis and to put units!

RESPONSE TO COMMENT 3/6/2012

What you are trying to find on this graph is optimum length of the muscle, not threshold. Look at your stimulus voltage to see how many motor units are being recruited. 


If you still have questions, send me an email! I'll be on my computer all day...
-Chrisoula

Hello everyone, Just want to give you a heads up that this week's lab is VERY long. Please carefully read your lab book prior to class so things go as smoothly as possible. Otherwise, you may not be able to complete the lab in the time alloted. Thanks! See you tomorrow. Chrisoula

Lab 3 question #1

Use page 42 of your lab book as a guide. This will help you find the pathway in the right amount of detail. 

Question #3

Q: Do I need to use the Nernst equation to calculate the overall electrical force/gradient?


A: You are supposed to use other resources and what you've learned from lecture. So yes, you can use the Nernst equation and other outside resources to answer the last part of question 3.

Homework questions 1 and 2

These questions are similar to Lab questions 14 and 15.  The membrane is permeable to K+.

Homework question 3

You are to answer this question based on the cell's overall electrical gradient, not Cl's individual electrical gradient.

Q:    I am wondering if you can clarify Q15 on the bean lab we did this past week. 

This was my answer to that question: 

The cell will become more positive, because it is gaining K+..is this correct?

The resting membrane potential difference will decrease..this is what I do not understand. If the difference decreases how is it going closer to zero, when it is already negative?

A:   Yes, the membrane potential in question 15 does become more positive.

As for the second part of your question, this concept is a bit tricky to understand at first, so I'm glad you asked this question!

Remember that every time we say "membrane potential" we actually mean "resting membrane potential difference" (see page 17 of lab manual for explanation). Don't forget that "difference" because that is the most important part (I always have to remind myself!).  

The membrane potential simply measures the difference in charge between the ICF and the ECF. 

Because we always set the ECF charge to 0, a positive membrane potential means the ICF is more positive than the ECF. A negative membrane potential means that the ICF is more negative than the ECF. 

But, in this case, it doesn't actually matter what sign (+ or -) the membrane potential is, the most important thing is how big the number (i.e. absolute value) is. The larger the number, the larger the difference in charge between the two sides of the membrane. If the membrane potential is 0mV, that means there is no difference in charge between the ICF and the ECF.

So in this case, we initially have a negative membrane potential (lets say -10mV, just as an example). This means the ICF is more negative than the ECF. 

Then suddenly the membrane potential becomes more positive (Let's say from -10mV to -8mV). This means that the the ICF becomes less negative, right? So the absolute value ( which is 8) of the membrane potential becomes smaller, i.e. closer to 0.

You can also look at it another way. If you use the number line on page 17. As you can see, -8mV is closer to 0 than -10mV.

  I---I---I---I---I---I---I---I---I---I---I---I

-10     -8                               0

Q: When I am looking at the membrane potential moving closer or farther away from zero mV to determine if is depolarize or hyperpolarize, am I supposes to looking at the zero mV pertain to the ECF?  

A: In general, yes, consider the ECF to be 0mv.

However, in this exercise, you don't need to know the exact number of mV on each side. You just have to know if the difference between the two sides is becoming larger or smaller.

Q:  What is repolarizes?  What is action potentials and when does it occur so that all cells are firing it?  Is the resting membrane potential of the cell, the ICF?  In question 3, do I have to use the information that Cl concentration in the ECF is 150mM and the Cl concentration in the ICF is 15mM, so that I can solve this problem?  Lastly, is it alright that you explain to me about the open and closing of Cl channels?  I really don't understand it.  The only thing I get from it is that it needs to be trigger into being the open state.  I'm assuming that the Cl channel only allows Cl to enter into the cell. 

A: My answers to your questions are below:

What is repolarizes?  What is action potentials?

This animation explains it better than I can through email (see link below). I also expect that Dr. Rechs will get to action potentials next week, if he hasn't already. There is also an explanation in your text book.

http://outreach.mcb.harvard.edu/animations/actionpotential.swf

 and when does it occur so that all cells are firing it? 

To fire an action potential, the cells need a stimulus.

 Is the resting membrane potential of the cell, the ICF?  

I'm sorry, I don't quite understand what you are asking here. The ICF simple means "intracellular fluid." Resting membrane potential is explained in detail on page 17 of your lab manual. 

In question 3, do I have to use the information that Cl concentration in the ECF is 150mM and the Cl concentration in the ICF is 15mM, so that I can solve this problem? 

Yes, you can use those numbers if you want. The important thing is that you know that there is a higher Cl- concentration in the ECF than the ICF.

Lastly, is it alright that you explain to me about the open and closing of Cl channels?  The only thing I get from it is that it needs to be trigger into being the open state.  

The only thing you need to know is that the Cl channels are normally closed and GABA opens these Cl channels. GABA is the trigger.

I'm assuming that the Cl channel only allows Cl to enter into the cell.  

Yes, that's right.