Lab Exam 2: Lab Reports

Question 1

Compare the Rectus femoris with the adductor pollicis for the following features:

• Total number of muscle cells (few or many)
• Total number of cells per motor unit (few or many)

Answer 1

Rectus femoris: many on both

Adductor Pollicis: few on both

Question 2

Which muscle can produce contractions of different strengths (weaker and stronger)? How?

Answer 2

2. Both rectus femoris and adductor pollicis can produce contractions of different strengths, weaker or stronger, by recruitment of motor unit. Recruitment of more motor units results in more strength, while recruitment of less motor units results in less strength. .

Question 3

Which muscle can produce the stronger contraction? Why?

Answer 3

3. Rectus femoris muscle can produce the stronger contraction because it has more number of muscle cells. A large number of muscle cells results in gross movement which results in greater strength of movement.

Question 4

Which muscle can produce more precise movement? why?

Answer 4

4. Adductor pollicis muscle can produce more precise movement because it has fewer number of cells per motor unit. Small motor unit results in precise movement.

Question 5

Which muscle can produce continuous contraction? How?

Answer 5

5. Both the rectus femoris and adductor pollicis can produce continuous contraction due to tetanus and recruitment.

Question 6

Which muscle will fatigue first during continuous, moderate strength contraction? Why?

Answer 6

6. Adductor pollicis will fatigue first during continuous, moderate strength contraction because there are fewer number of motor units to recruit.

Question 7

What are the causes of fatigue?

Answer 7

ionic imbalance, relative lack of ATP, and a buildup of lactic acid.

Question 8

What happens to the strength of contraction as fatigue occurs? Why does this change in strength occur?

Answer 8

8. Strength of contraction decreases as fatigue occurs because there is a decrease number of functioning motor unit.

Question 9

After an injury, some of the motor neurons to a muscle are dead. The surviving motor neurons may form new branches that extend to more muscle cells. How would this affect movement and strength?

Answer 9

More muscle cells result in larger motor unit which causes more gross movement. And decrease number of motor units decreases strength.

Question 10

Where does the perception of touch and temperature occur? What does the map of this region (sensory homunculus) tell you about the density of receptors in different body areas?

Answer 10

2. The perception of touch and temperature occur in the sensory cortex. The map of sensory homunculus shows the density of sensory receptors. If a relatively large body part occupies a relatively small region of the cortex, that indicates it has a low density of receptors.

Question 11

how did your perception of temperature change while your hand was in hot water? what was the reason for that change in perception?

Answer 11

3. The temperature changed the longer I leave my hand in the hot water from hot to warm due to the phasic sensory adaptation of the hot sensory receptors in my hand.

Question 12

When both hands were placed in the warm water, which temperature receptors in each hand were sending nerve impulses?

Answer 12

4. When both hands were placed in the warm water, the left hand’s hot sensory receptors were sending nerve impulses to the brain, while the right hand sent electrical signal from the cold sensory receptors.

Question 13

Placing a hand in hot water will change the sensitivity of the hot and cold receptors. Which results support your choice?

Answer 13

5. The experiment consisted of three different water temperatures utilizing two thermoreceptors, hot and cold. Based on my result, placing a hand in hot water will change the sensitivity of the hot receptors only. Using only the hot water will only activate the hot sensory receptors to send nerve impulses to the brain.

Question 14

Glucose and fructose are made of the same number and types of atoms. Why do they taste different?

Answer 14

8. Glucose and fructose are made of the same number and types of atoms. However, fructose taste sweeter than glucose. They taste different because they have different 3-dimensional shapes and they bind to receptors differently and that stimulates the receptors to send different frequencies of action potentials. When fructose bound to the sweet receptors, it stimulated the sweet receptor to send a higher frequency of action potentials, so it was perceived as more intense, sweeter.

Question 15

Aspartame is made up of two amino acids. Why is it sweet-tasting if it is not even a carbohydrate?

Answer 15

9. Aspartame is made up of two amino acids and is not a carbohydrate, yet it is still sweet-tasting because its molecular structure allows it to bind to the sweet receptors and that stimulates the sweet receptors to send action potentials to the brain, which perceives it as sweet.

Question 16

Some people have been advised by their physicians to cut down on salt (NaCl) and use salt substitute (KCl) instead. These people tend to use too much salt substitute. Based on your results, explain why.

Answer 16

10. Some people have been advised by their physicians to cut down on salt (NaCl) and use salt substitute (KCl) instead. These people tend to use too much salt substitute because NaCl is saltier than KCl so they compensate to get the same taste. When KCl interacts with salty receptors, the receptors send a lower frequency of action potentials, so we perceive it as less intense.

Question 17

How would the death of receptors affect perception?

Answer 17

11. The death of receptors affects perception. A decrease of receptors causes a decrease in transduction which causes a decrease in perception.

Question 18

What is your visual acuity value (both eyes)? what does this number mean?

Answer 18

2. My visual acuity for both eyes with glasses is 20/15, which means that when I am 20 feet away, I see what the average person sees from 15 feet away. However, my visual acuity for both eyes without glasses is 20/70, which means that when I am 20 feet away, I see what the average person sees from 70 feet away.

Question 19

Two people of the same age have very different near point measurements. How is that possible?

Answer 19

3. Two people of the same age could have very different near point measurements because of the difference in the elasticity of their lens.

Question 20

In the blind spot demonstration, what did you “see” in place of the figure that disappeared? Does “seeing” occur in the eyes or in the brain?

Answer 20

I saw the background paper in place of the figure that disappeared. The brain interprets what we see and fills in the blank space where blind spots occurs, therefore “seeing” happens in the brain.

Question 21

Is your visual awareness always an accurate representation of reality?

Answer 21

5. Visual awareness is not always an accurate representation of reality. In the binocular rivalry experiment, my brain perceived that there was a huge hole in my hand. In real life, my hand was whole and intact.

Question 22

What are the class averages for pupil size in bright light and dim light?

Answer 22

6. The average for pupil size in bright light was 3, whereas the average for dim light was 6.

Question 23

What abnormalities can be detected by observing the retina with an opthalmoscope?

Answer 23

7. Abnormalities can be detected by observing the retina with an ophthalmoscope, such as torn retina, burst blood vessels, and retinal detachment.

Question 24

Why are vision and hearing tests given as part of a regular physical exam and to young children before starting school?

Answer 24

to see if they have any deficiency that could result in learning difficulties so that accommodation can be planned.

Question 25

How is sound located? Why are we often inaccurate locating sound that originate in the midsagittal plane?

Answer 25

Sound is located by the difference in time of arrival of the sound in each ear and the difference of loudness of the sound in each ear. We are often inaccurate locating sound that originates in the midsagittal plane because sound arrives at the same time in each ear and it has the same loudness in each ear.

Question 26

Predict the results of Rinne and Weber’s tests in someone with conductive hearing loss

Answer 26

• Rinne’s test would result in the person hearing vibration if the tuning fork is on their mastoid process but would be unable to hear anything if the fork is in front of their ear canal.
• With Weber’s test, the person would hear the sound louder in the ear with the conduction problem because the good ear is also processing ambient and surrounding noise while the “bad” ear only hears the tuning fork

Question 27

Predict the results of Rinne and Weber’s tests in someone with sensory hearing loss.

Answer 27

• Rinne’s test would result in the person not hearing anything at all whether the fork is on their mastoid process or in front of their ear canal. In
• Weber’s test, no sound would be heard on the bad ear, but the sound will be heard in the good ear.

Question 28

Which conditions produced the most starch digestion?

Answer 28

increase in concentration of enzyme, room temperature, and neutral pH.

Question 29

Does cold temperature denature enzymes? How do you know?

Answer 29

2. Cold temperature does not denature enzymes. During the experiment, once the enzymes were brought back to room temperature, positive results for breakdown occurred proving that cold temperature only slows down enzyme function

Question 30

Compare the effects of HCl on protein digestion and starch digestion.

Answer 30

3. During protein digestion, HCl activates pepsin due to the decrease in pH. During starch digestion, HCl denatures enzymes.

Question 31

Explain why frozen food keeps (does not spoil - grow mold or bacteria) longer than food stored in room temperature

Answer 31

4. Frozen food keeps longer than food stored in room temperature because cold slows down enzyme activity of the bacteria and/or growth of mold.

Question 32

How does cooking food affect enzyme activity? (This refers to enzymes in the food.)

Answer 32

5. Cooking food denatures enzymes. The changes we see in cooked food are due to the denatured protein.

Question 33

Which conditions produced the most protein digestion?

Answer 33

6. The conditions that produced the most protein digestion were low pH condition, higher concentration of enzymes, and room temperature.