Explain why rigor mortis occurs
Lab 7 The Muscular System BIO201L
Student Name:Emily Vu
Access Code (located on the lid of your lab kit):AC- 61FZVB3
Pre-Lab Questions
”1. How do banding patterns change when a muscle contracts?”
”2. What is the difference between a muscle organ, a muscle fiber, myofibril and a myofilament? ”3. Outline the molecular mechanism for skeletal muscle contraction. At what point is ATP used and why? ”
”4. Explain why rigor mortis occurs. ”
Experiment 1: Tendons and Ligaments
Post-Lab Questions
”1. Label the arrows in the slide images below based on your observations from the experiment. ”
A- chondrocytes
B- collagen C- nucleus
D-skeletal muscle fibers E- nuclei
F- collagen fibers
”2. How does the extra cellular matrix of connective tissues contribute to its function? ”
”3. Why are tendons and ligament tissues difficult to heal? ”
”4. What difference do you see between the tendon – muscle insertion image and the tendon image? ”
”5. What differences do you see between the tendon and ligament sections? ”
Experiment 2: The Neuromuscular Junction
Post-Lab Questions
”1. Are there few or many nuclei at the end plate? ”
2. What is a motor unit? ”
3. How is a greater force generated (in terms or motor unit recruitment)? ”
4. What types of sensors are present within the muscle to identify how much force is generated? ”
Experiment 3: Muscle Fatigue
Table 2: Experimental Counts
| Trial 1 | Trial 2 | Trial 3 | Trial 4 | Trial 5 | |
| Predicted Value | 27 | 29 | 25 | 22 | 24 |
| Actual Value | 25 | 22 | 20 | 18 | 22 |
Post-Lab Questions
”1. How did the predicted results compare to the actual results? ”
2. Did you notice any changes in the number of repetitions you could perform, or how your hand felt after each of the trials?
3. Explain the actions that were occurring at the cellular level to produce this movement. Include sources of energy and any possible effect of muscle fatigue.
4. Hypothesize what would happen if blood flow was restricted to the hand when this experiment is performed.
Experiment 4: Gross Anatomy of the Muscular System
Table 3: Gross Anatomy Data
| Movement | Muscle(s) Activated | Action(s) of Muscle(s) |
| Forearm Extended (Step 1) | tricep brachii | flexion and extension |
| Fingers Extended and Splayed (Step 1) | extensor digitorum | extension and move outward |
| Fingers Retracted (Step 1) | interossei | extension |
| Forearm Pressed Down Upon (Step 2) | bicep brachii | elbow flexion |
| Elbow Bent (Step 3) | bicep brachii | elbow flexion |
| Arm Raised to Side with Heavy Object (Step 4) | deltoid, trapezius | lifting |
| Arm Extended Back with Heavy Object (Step 4) | deltoid, trapezius, tricep | lifting |
| rotating ankle | tibialis anterior muscle | rotation |
| raising leg | anterior hip flexor | lifting |
Post-Lab Questions
1. Label the human muscle diagram.
A – pectoralis major muscle
B – flexor carpi radialis muscle
C – vastus medialis
D – bicep
E -flexor carpi radialis muscle
F – deltoid
G – rectus femoris muscle
H – tibialis anterior muscle.
2. Which muscle(s) were used to extend your arms backward?
tricep brachii.
3. Which muscle(s) were used to extend and splay your fingers outward? extensor digitorum
Experiment 5: ATP and Muscle Fatigue
Table 4: Muscle Fatigue Data
| Trial | Time (seconds) |
| Trial 1 | 52 |
| Trial 2 | 45 |
| Trial 3 | 48 |
Post-Lab Questions
”1. What happened to the time intervals between Trial 1 and Trial 3? What caused this change? ”2. Identify three muscles which were engaged during the wall-sit.
3. Explain the biochemical reasoning behind muscle fatigue. ”
· muscle fibers lack of ATP and calcium Experiment 6: The Virtual Model – The Muscular System (Upper Body)
Insert screenshot of the latissimus dorsi muscle:
Insert screenshot of the greater pectoral muscle:
Insert screenshot of the brachial muscle:
Post-Lab Questions
”1. What is the scientific term for the muscles of the mouth? ”
2. What is the scientific name of the muscle that facilitates the raising of the lower lip? Is it on the ventral or dorsal side of the body?
3. Which muscle is deeper in the body: the internal oblique muscle or the transverse abdominal muscle?
4. Is the trapezius muscle located in the abdomen, back, head, neck or thorax? ”
5. What muscle is more medial, the deltoid muscle or the greater pectoral muscle?
greater pectoral muscle.
Experiment 7: The Virtual Model – The Muscular System (Lower Body)
Insert screenshot of the semitendinous muscle:
Insert screenshot of the soleus muscle:
Insert screenshot of the gracilis muscle:
Post-Lab Questions
1. What is the role of the long extensor muscle of the toes? Which toes does it control?
2. What is an adductor muscle? List three examples of adductor muscles here.
3. Is the gracilis muscle located in the foot, hip, leg, or thigh muscle group?
4. Relate the location of the semitendinous muscle and the greater gluteal muscle.
5. Which muscle is most distal: the pectineal muscle, the soleus muscle, or the abductor muscle of the great toe?
Experiment 8: Fetal Pig Dissection – Muscular System
Table 5: Experimental Data
| Muscle | Origin | Insertion | Movement |
| Pectoralis major | Click here to enter text. | Click here to enter text. | Click here to enter text. |
| Latissimus dorsi | Click here to enter text. | Click here to enter text. | Click here to enter text. |
| Deltoids | Click here to enter text. | Click here to enter text. | Click here to enter text. |
| Rectus abdominis | Click here to enter text. | Click here to enter text. | Click here to enter text. |
| Transverse abdominis | Click here to enter text. | Click here to enter text. | Click here to enter text. |
| Gluteus medius | Click here to enter text. | Click here to enter text. | Click here to enter text. |
Post-Lab Questions
”1. Describe the tissue that covers muscles. ”
”2. How many layers of abdominal muscle are there? ”3. What direction do the muscle fibers of the external oblique run? ”
”4. Why are muscle fibers considered excitable? ”
”5. Why is it important to have both flexors and extensors? ”
6. How can muscle mass be influenced by training or age? ”
