Quiz 8 guide + Action potentials in nerve: lab preview + Grades

Quiz 8 guide
By far most predictable questions you can have from what we have done in lab.
Go over entire theory of
- How food is really digested
- Role of muscles in digestions (those wave like movements & grinding of food). Remember these muscles and their actions. Pretty much entire first page in your lab manual.
- Three different neurotransmitters and their mode of action. The flowchart that I drew should be enough.
- What things will they effect i.e. frequency, amplitude, muscle tone, velocity and how will they effect i.e. increase or decrease and under what conditions i.e. if you add different neurotransmitters singly or in combination or when you stretch and under effect of anoxia.
- Also should be known is the fact that the stretching exercise was done to resemble an action of muscle when you gobble food.
- Most interesting of all know your calculations and what was the solution that you used to keep your intestine into and why did you use it. (These are kind of more applied questions related to your lab).


Action potentials in nerve: lab preview
- How do nerves carry our signaling and at what rates? This is what we want to learn from this lab.
- Upon stimulation nerves generate action potential. Each nerve is composed to many axons. In the first part of the experiment we will try to generate Single Action Potential (SAP) using the simulator program APSIM
- In second part we will give you frogs sciatic nerve that is a bundle of three axons (alpha, beta and gamma). This will generate Compound Action Potential (CAP) upon stimulation i.e. you anticipate to record the responses from all three axons. However the response from the gamma subunit is weak that we cannot visualize. But we will get responses from alpha and beta subunits.
- Third thing will be study of refractory period
I will leave first part on you to finish. Probably neither Faeez or I will be there to help you because taking out sciatic nerve is one great Halloween treat for TA’s.

Grades
Quiz 6: Isometric contraction
Class average: 81
Highest: 100
Lowest: 72.5

Worksheet 7: Isotonic contraction
Class average: 98.82
Highest: 100
Lowest: 90

Quiz 7 guide + smooth muscle lab preview + grades

Quiz 7 guide

Isotonic muscle contraction

- Once again should know difference between isotonic muscle contraction and isometric muscle contraction.
- Why or how does isotonic muscle contraction.
- How does load affect contraction, speed of contraction and change in muscle length. From this you can calculate work.
- The general trend of graphs: relationship of muscle shortening to load, isotonic contraction with increasing, relationship of velocity of contraction and load.
- Remember how you calculate the velocity [v=y(distance)/x(time)] and work (work= force x distance).
- Change in the set up of isometric contraction and isotonic contraction. This means if someone puts a setup on the exam with muscle you should know what experiment they are referring to. Also another difference in the set up is that of 5mm adjustment. You use 5g weight in isometric and the knob in isotonic contraction.


ATP and Muscle contraction

- The introduction section of contraction. The entire theory behind how the contraction occurs. I really prefer you read the sliding filament theory in your textbook (pg: 291-292). On further pages you will get description of the contraction cycle. While reading I would also recommend to take a look on the animation in your Interactive Physiology CD-Rom that came along with your textbook.
- Optional: And since you have reached these pages why not to go ahead and read on muscle tension, and isotonic & isometric contraction.
- Plus the results: What happened when you added ATP to the muscle.
- I will not ask something like what is the % contraction of a muscle that you might be calculating using the values of original length and post-treatment lengths given to you. However for the final exam I cannot assure anything so just remember it.
- Good animation of above process available online at http://www.blackwellpublishing.com/matthews/myosin.html
Thanks to Emily for sharing this.





Properties of smooth muscle action lab- preview

- We shall be using small intestine of mice to understand action of smooth muscle. This means that how smooth muscle is involved during digestion of food through small intestine (theoretically), how nervous system controls this process with help of different neurotransmitters (experimentation).
- Since you are accustomed to the programs that we use it should not be a big problem. The only this that you need to take care of is always maintain the temprature at 37 C of tyrodes solution inside the beaker where you have the piece of small intestine.


Class averages

Quiz 5 (Membrane potential & Excel)
Avg: 76.47
High: 90
Low: 34

Worksheet (Isometric contraction)
Avg: 92.94
High: 95
Low: 90

Quiz 6 guide + isotonic lab preview + grades

I appreciate sincere and honest evaluations that few of you gave to me. Those who did not hand in yet can do so as it helps me know how comfortable you are with this lab and what more can I do for you? I shall be elaborating everything as I was asked to do. Those who hate to read long things, forgive me/get use to it.

Also read comments posted by Matthew and Allison last time. Do you have any more inputs to what they have to say?

QUIZ TIPS
Muscle microanatomy
Should be able to identify any labeled region on EM of skeletal muscle or on slide (the same that you did on your worksheet)

Isometric muscle contraction
- Definitions of contraction, tension, load and what is isometric contraction.
- It is important to understand the length tension curve as shown in figure 2 in lab manual that demonstrates under what circumstances of muscle length you will see either increase or decrease in tension. Also important is the role of cross-bridge formation by actin and myosin filaments that results in tension.
- Plantar flexion and dorsi flexion (once again I apologize for this).
- Should remember how you dissected the muscle (gastrocnemius), where did you tied the knot (at Achilles tendon) & what bone did you cut (tibiofibula). Also remember how you went for hanging this muscle on the clamp and force transducer (This is trivial right now, however during final exams there will be few questions where someone might actually put an experimental setup and ask you to identify the error in experimental set up)
- What is recruitment, maximal stimulus and frequency modulation?
- The general trend (graph, figure 7 in lab manual) of muscle response to increasing stimulus frequency. You are expected to remember and label (if asked to) the threshold stimulus, recruitment, maximal stimulus, frequency modulation & tetany.
- Keep all three graphs that you generated with you. If you have handed me one graph for a group feel free to print the saved graph from computer. This one’s a useful data.

Isotonic muscle contraction lab preview
- Try to correlate differences between Isometric and Isotonic muscle contraction.
- How Isotonic muscle contraction works?
- Again you have three different graphs
- Procedure for muscle preparation remains to be the same. I will give you frog’s leg. First measure the plantar flexion and dorsi flexion and dissect the same way.
- Notice the difference in the experimental set up as compared to isometric. I would like to know from you why do we have this difference.
- In another experiment, we shall be playing with isolated muscle fibers and try to see how calcium and ATP effects the physiological length. Again for this we have a simple theory that calcium and ATP is required for actin and myosin to form cross bridges helps them slide.


GRADES

More to come....
class average of last quiz & worksheet

Quiz 5 guide + general

Things to be expected:

from Excel
Atleast one question from this section. This will be to test how much you have learnt excel over the past 4 labs.

Membrane potential
What is a membrane potential, resting potential, action potential.
The Nernst equation
Nenrst potential for ions (both negative and positive)
Parallel conductance equation
What equations are used for single ions and multi ions
Under what circumstances your cell gets depolarized, hyperpolarized.
How will changes in concentrations Na, K and Cl, both intracellularly and extracellularly affect the membrane potential as well the latency and amplitude of the membrane potential?
How stimulus-response relationship (all-or-none response) works?

One question from upcoming lab of isometric muscle mechanics. It is going to be a long one so come prepared

General
Please donot forget to bring back TA review sheets. These will be helpful to me. Feel free to write what-so-ever is appropriate.

Also I will be giving mid term grades.