MCB Lab Final

We will determine the heart rate by counting the number of R-waves in one minute. Assume you get a baseline measurement of 45 R-waves per minute. You add a chemical onto the heart and after 2 minutes the heart reaches a steady state of 30 R-waves per minute. What is the change in heart rate (in beats per minute) caused by the chemical? Write your numerical answer in the space below (do not include units).

-15

What is insulin?

A hormone that causes target cells to take up glucose from the blood

Which of the following statements is correct?

One motor neuron can control multiple muscle fibers

Plasma membranes are semi-permeable. Which of the following molecules can simply diffuse across the plasma membrane (without the use of a transporter or channel)?

Oxygen

Which part of the body do you expect to have the largest two-point discrimination threshold (i.e. the longest distance)?

Shoulder

In the facilitated diffusion animation, the membrane permeability for the blue particle was greater than for the green particle (in step 7 and 8). How did membrane permeability affect the rate of diffusion?

The greater the permeability, the faster the rate of diffusion

If you spin around in a circle over and over, your vestibular system will be activated to try to maintain your balance. However, if you stop quickly you may feel dizzy, because fluid in the semicircular canals is still moving around.

vestibular semicircular canals

When high Ca+2 is put on the frog heart, it inhibits the causing the heart rate to

voltage-gated Na+ channel decrease

In the potentiation experiment (part V) you need to stimulate your subject for 20 seconds at 10 Hz. How many stimulation pulses is that?

200 ( 20 X 10)

When you press on the hand dynamometer, Labscribe will record a change in voltage. In order to convert voltage into a force measurement (Newtons), you will use a conversion equation that you find when you calibrate the dynamometer. Assume the equation you got from calibration was y = 200x + 10. You then perform the forearm experiment and measure the peak voltage from the hand dynamometer as 0.1 V. What is the force generated by the muscle? Write the number below in Newtons (just enter a number, not the units). Hint: This is explained in the lecture slides.

30

A common experiment in neuroscience labs is to stimulate a nerve from frogs and record the compound action potential in response. The results from this experiment are shown below. The stimulation electrodes were kept constant and the recording electrodes were moved to two locations, resulting in two different recordings of the CAP (record #1 and record #2 in the graph). The two different recording sites were 14 mm apart. Note that the time scale is in milliseconds (ms). Determine the nerve conduction velocity in m/s. Write the number in the space provided (do not include the units).

35. ( Calculating) V= Distance/Time

If the duration of a single twitch is 0.25 secs, at which stimulation frequency do you predict summation will first occur? Write the number in the space provided. Don't write units (your answer should be in Hz).

4

What is the distance between two cones (i.e. the image size you calculate in experiment 2B)? Write your answer in micrometers (a micrometer is 1/1000x a millimeter, so multiply your mm answer by 1000 to get micrometers). Write only the number in the space below (do not include the units).

4.56

Which of the following images correctly shows the placement of the red and black electrodes on the frog heart? The heart is oriented as if the frog's head were up and the right (R) and left (L) sides are labeled. Read the directions in the lab manual to determine the exact placement.

A

What is a follow up experiment to the dialysis bag experiment that you could do? Think about what else you could test with a similar set-up. Briefly explain the experiment and write a hypothesis for this new experiment. This will help you get ready for writing the discussion in the lab report. Feel free to reuse your answer in your lab report.

A follow up experiment would be the Beneicts test. The experiment would have the same set up as the experiment we just did expect we test just the water from the maltose. We would be experimenting with the levels of sugar. The hypothesis would be that there will be a positive test for maltose.

What causes color blindness?

A genetic mutation that affects the cones

You may have noticed that at high stimulation intensities, the twitch tension reached a maximum and would not increase beyond that. Why does twitch tension reach a maximum even as stimulation intensity increases?

All the motor units in the muscle have been recruited

You must press the __________ button in LabScribe in order for changes to the stimulator amplitude to take effect.

Apply

You do experiment 3B: Auditory threshold and make a graph of your results. Remember that in this experiment you measure the intensity threshold for tones at different frequencies. Which one of the following graphs is what you would expect? Be careful when you select answers, because they may not be arranged in order from A-D.

B

What is the main safety concern in this lab?

Be careful not to leave the blood pressure cuff inflated for too long

Why is the T-wave of an ECG positive? (see the lecture)

Because ventricle muscle cells have different lengths of action potentials and the cells that depolarize last have the shortest action potentials

Which of the following images is of the muscle transducer we will use to measure the movement of the pinky finger?

C

Which of the following statements about the compound action potential (CAP) is correct?

CAP amplitude increases as the stimulation intensity increases

What cellular process causes muscle contraction to stop?

Calcium is pumped back into the sarcoplasmic reticulum

We are going to use our dataset to see if we can predict if a subject has diabetes or not. Therefore, the column in our dataset called "Outcome" is the

Class

You record 10 reflex responses in a row, but you can only see one response on the screen. If you want to see all 10 reflex responses on the screen, which button would you press in LabScribe. (Review Lab 0 if you don't remember)

D (Two mountains)

Write the citation for the article your group chose related to diffusion. Your citation should include the authors, article title, date, journal name, issue number and page numbers. See the Library Guide for how to properly cite a journal article.

De, Debajyoti et al. "Glucose-induced structural changes and anomalous diffusion of elastin." Colloids and surfaces. B, Biointerfaces vol. 188 (2020): 110776. doi:10.1016/j.colsurfb.2020.110776

Review of LabScribe (see Lab 0 to review) When using LabScribe, which of the following buttons will automatically rescale the y-axis to fit the data onto the screen?

E ( The one with an up and down arrow

What term do we use to describe the movement of a polar molecule, like glucose, across a membrane from high concentration to low concentration (i.e. with its concentration gradient)?

Facilitated diffusion

Using the same figure as question 2, if the membrane is only permeable to water, what is the net direction of water diffusion? Hint: don't count the blue dots. The volume of both sides is the same and you can see where the sugar is more concentrated.

From left to right

This image shows the starting conditions of a diffusion experiment. If the membrane is permeable to sugar, what is the net direction of sugar diffusion?

From right to left

Which of the following do you need to do in order to make sure the heart rate monitor works correctly? Select all answers that are correct (there are two correct answers).

Get the heart rate monitor wet The sensor needs to firmly touch the skin

Write a hypothesis for experiment 4C: Solutions at three temperatures. What do you think the room temperature water bath will feel like to each hand and why?

Hypothesis: The room water temperature will feel a bit colder to the hand that was just dipped in cold water and a bit hotter to the hand just dipped in hot water.

Which experiment in Lab 2 are you most excited or interested in trying? Briefly explain why. [1-3 sentences total]

I am most excited about getting to test the vestibular system. The overall experiment for this one seems fun getting to test out how our vestibular reflexes come out when sensing of motion of dizziness. I don't get dizzy easily so I am excited to see if this test will work out for me!

Write a complete hypothesis for this experiment. Make sure to include the results you expect to see from the I2KI and Benedict's test and why you expect those results. The hypothesis should be 1-2 sentences long. Your answer will be graded later.

I predict that the I2KI would have a change of color because the size molecule of starch is smaller compared to glucose. As for the benedicts there would also be a color change due to the temperature change.

Which of the following would delay ventricle repolarization at the end of systole? Hint: Look at the lecture slides for the frog heart lab to see what causes repolarization in contractile heart cells.

Impaired voltage-gated K+ channel

What colors would you expect (after waiting 40 minutes) if the experiment started with glucose and I2KI inside the bag and starch in the beaker? Explain the colors related to starch + I2KI and the colors you expect after doing the Benedict's test. (Study question #2)

In the beaker we expect the color change to purple. When I2KI + starch the colors turn to purple or black, so the colors expected from the Benedicts test would be orange or red. This is an expected color change from both because there was glucose in both experiments. Ours turned to a bit of a peach/orange color. This is an indicator that the glucose is present.

What will happen to the compound action potential (CAP) as the stimulation intensity increases?

Increase - a higher intensity will activate more muscle cells and and the CAP will summate to a larger amp

Which of the following changes would cause an increase in the diffusion rate across a membrane? Select all that are correct (there are two correct answers).

Increase concentration gradient across membrane Increase surface area of membrane

After a meal (i.e. the fed state), which one of the following would happen? Select twocorrect answers.

Increased GLUT4 transporters in the membranes of cells Glycogen synthesis

During the fatigue experiment you will be squeezing the hand dynamometer at 50% of your maximum for several minutes. During this experiment, what kind of contraction are your forearm muscles performing?

Isometric

Why did we have one tube filled with water in the Benedict's test?

It acts as the negative control, so we have a reference for when there is no glucose in solution

If the solution in the bag and in the beaker are a dark purple color after 45 minutes of the diffusion experiment, what does that specifically tell you about the permeability of the dialysis bag? (Note: this is before you do the Benedict's test)

It is permeable to starch and I2KI

Oh no, your heart rate monitor is not functioning properly! What should you do?

Manually count heart beats or use the automatic blood pressure cuff to record heart rate

Which of the following steps should you do right before you add starch to your dialysis bag?

Mix the starch solution

This diagram shows the patellar stretch reflex. Letter D is pointing to motor neurons . The inhibitory interneuron is labelled by E .

Motor Neurons E

We will be observing heart rate with respect to what three variables? Check all three variables.

Neurotransmitters Electrolytes (Ca+2 and K+) Temperature

Once a system has reached equilibrium across a membrane and both sides are of equal concentration, will individual molecules stop crossing the membrane? (study question #6)

No, individual molecules keep crossing the membrane at equilibrium

In general, where should the green ground electrode be placed?

On top of Bone

Based on the graph you made in the Jupyter notebook, which average reaction time was faster? Briefly explain why that would be faster. Hint: It has to do with the anatomy of how visual and auditory sensory information make their way to the brain.

Our auditory reaction times were faster. It was faster because with the audtoutary response it took much less time for it to signal it to the brian cortex, as opposed to the visual one. Aswell because the sensory pathway it takes longer to respond making it why it took a bit longer for the visual reaction to react.

When was the gastrocnemius muscle most active?

Plantarflexion

If there is a lot of background noise in your EMG recording from the gastrocnemius muscle, what can you do to reduce the noise?

Prevent the wires from moving by taping them to the leg

What type of sensory receptors are muscle spindles?

Proprioceptors

If the wrong finger is twitching when you stimulate the muscle, what should you do first?

Reposition the red and black electrodes on the hand

I got this error message while trying to determine the mean reaction times of my lists. It says "name 'np' is not defined." What do I need to do to correct this error? Hint: Look at the data science guide posted in the modules and look under "NameError". It's similar to the example with "Table".

Run the cell above where the numpy library is imported

Show your work for how you determined the predicted stimulation frequency at which summation will first occur (Table 2). Use the following format and include units: Stimulus amplitude: Twitch duration: Predicted summation frequency:

Stimulus amplitude: 7amp Twitch duration: 200ms Predicted summation frequency: 1ms/200ms converted to HZ = 5HZ Measured Summation Frequency (HZ): 3Hz

What signal is detected by EMG?

Summed signal from many action potentials occurring in many muscle fibers

How do we analyze the EMG activity from our recordings?

Take the absolute integral in a one second period

In lab 6 we saw that warm temperature caused heart rate to increase above baseline. What is the null hypothesis for this experiment?

The changes we saw in heart rate were due to random chance

Based on your results, what molecules is the dialysis bag permeable to. Briefly explain how you know this.

The dialysis bag is permeable to glucose and I2KI. We know this by the color change of it. Which resulted to it being purple.

Compare the frog and human heart. Which of the following statements are correct. Select all the answers that are correct (there are 3 correct answers).

The human heart has two ventricles and two atria The frog heart has three chambers Oxygenated and deoxygenated blood mix in the frog ventricle

Write a hypothesis for the experiment that compares the timing of the patellar stretch reflex with the timing of voluntary movement of the leg. Remember to include your prediction and an explanation of why you expect that.

The hypothesis is that the timing from the patellar stretch reflux will be a much faster response time compared to the voluntary movement from the leg. This is expected because the stretch reflex is just going to the spinal cord and then back out as compared to the voluntary leg movement. Where's it goes through the brainstem to then activate the somatosensory cortex to then activate the motor areas.Then the signal is sent down the spinal cord and then activate the motor neurons in the spinal cord. The lastly activates the muscle to respond (kick).

In the facilitated diffusion animation, how did the charge inside of the cell change when the gated green channels opened (step 13), assuming that there were more green Na+ molecules outside of the cell to start.

The inside got more positive

Why do exercising muscles require so much more blood flow?

The muscles need oxygen so they can make ATP

What is the purpose of lateral inhibition? Does lateral inhibition give an accurate portrayal of the external world? Explain using your own words; do not copy from the lab manual! Limit answer to 2-5 sentences

The purpose of lateral inhibition is helps detected the borders of objects and create the visual perception of it there being a gradient in color. I would say the later inhibition does not give an accurate portrayal of the external world because the process itself is enhancing our perception to see in an increased contrast.

The withdrawal reflex occurs when you pick up something extremely hot that could burn you and you immediately drop it. Based on what you have learned about reflexes, answer the following question: You drop the hot object before you have a chance to really think about the situation. What makes this reflex so fast?

The reflex circuit only involves the spinal cord, not the brain

At the end of the diffusion experiment, one group of students conducts Benedict's test. After incubating the test tubes for 5 minutes, they record the following results: Control (water only): light blue Bag solution: light blue Beaker solution: light blue Which of the following procedural errors could have led to these unexpected results?

The test tubes were incubated at room temperature (rather than heated)

What should you pay special attention to when attaching the transducer to the leg for the patellar stretch reflex experiment?

The transducer should have one specific side, labelled "outside", facing away from the skin

Write a brief summary of the article you cited in the last question. This should be about 2-4 sentences. What were they investigating? What was the main finding? ( Lab 0)

They investigted glucose-induced structural changes and anomalous diffusion in elastin. The main finding was that the different levels of glucose consitration was what causes the changes around the skins tissue. So if there's a higher glucoe concetriaon it causes the prtoien to stiffen causing the skin to get more wrinkly.

For the ischemic hand grip exercise (part II.B), what is the purpose of the manual blood pressure cuff on the dominant arm?

To prevent blood flow, so muscle metabolites build up

Long QT syndrome is characterized by an extended time between the Q and T waves (QRS is normal). It is caused by problems with one type of ion channel in the ventricles. Think about the cardiac action potential and the relationship between that and the ECG. Which ion channel is impaired in long QT syndrome?

Voltage-gated K+ channel

The compound action potential we measured in Lab 3 (during the nerve conduction velocity experiment) was from the muscle cells in the hand, so we were recording an EMG in Lab 3. Why are the EMG recordings so much more complex, or "messy" looking, in Lab 5? (see the lecture)

We are recording activity during natural movement in Lab 5, so the muscle fibers will fire action potentials at different times

Which of the following statements is correct?

We expect that adding epinephrine to the frog heart will cause the heart rate to increase

In the Jupyter notebook we will look to see if there is a correlation between the number of pregnancies a subject has had and whether they have diabetes. Let's say we do a bootstrap analysis of the dataset and calculate a p-value of 0.024. What does this p-value mean (using the standard cut-off)?

We reject the null hypothesis

patellar stretch reflex

What is the reflex? Fast, involuntary, response to stimulus Stimulus: Tap under knee > Stretches Tendon > Stretch quads Neg Feedback Response: Quad Contract and shorten (response) > leg straightens

When will you first hear the Korotkoff sounds during blood pressure measurements?

When the blood pressure cuff has a pressure just lower than the systolic blood pressure

After completing one experiment on the frog heart (like putting epinephrine on the heart) you will wash off the solution using normal Ringer's solution. How long should you wait before doing the second experiment (like putting acetylcholine on the heart)?

You should wait until the frog has a stable baseline heart rate (i.e. the heart rate is no longer changing)

The eyes are able to focus on both near objects and distant objects. The ability of the eyes to do this is known as:

accommodation

How are neurotransmitters released from the neuron?

exocytosis

Think about your quadriceps (front thigh) and hamstrings (back of thigh). The quadriceps are [ Select ] ["flexors", "extensors"] and the hamstrings are

extensors flexors

Which area of the eye contains the highest concentration of cones and is responsible for discriminating fine details?

fovea

There are two cell-to-cell structures in the heart: An action potential will spread from one heart cell to another through a . Heart muscle cells create a lot of force during contraction, so it is important that the cells remain connected together via .

gap junction desmosome

Type II diabetes is characterized by

less sensitive insulin receptors

What did you calculate for the mean arterial pressure when you determined blood pressure with the pulse plethysmograph and via auscultation? Were the values similar? Why might there have been a discrepancy?

mean pressure = 1/3(Ps-Pd) + Pd=1/3Pp+Pd Mean pressure= 1/3 (852.90-817.7)= 130 The values were not similar, the values for auscultation were a bit higher than the plethysmograph. Were slightly different probably because the Ps is higher when the ventricles contract and the Pd decrease when the ventricles relax.

In the visual system, photons of light cause changes in the membrane potential of the photoreceptors. Thus, photoreceptors are the site of :

sensory transduction

In experiment III in lab 4, the stimulation intensity will be increased, which causes:

spatial summation

In the blind spot test, we will be measuring the distance between------and calculating the distance between------.

the cross and where the pencil tip disappears the optic disc and fovea

compound action potential CAP

the summed electrical activity from many muscle cells

When doing the frog dissection you need to be careful

to not remove the heart from the blood vessels