Understanding the Muscular System: Key Concepts and Experiments

Lab 7 The Muscular System BIO201L Student Name: Narek Hakobyan Access Code (located on the lid of your lab kit): AC-NFQUK Lab Report Format Expectations Utilize college level grammar and professional formatting when completing this worksheet. Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre- lab Questions 1. How do banding patterns change when a muscle contracts? It happens because the myofilaments of myosin and actin get shorter. This makes them come together, which makes the H zone shrink and get narrower. The A band stays the same, though. 2. What is the difference between a muscle organ, a muscle fiber, myofibril and a myofilament? Muscles are made up of groups of specialized cells and fibers that work together to move the body, which causes muscles to contract. Muscle fibers are single cells of muscle tissue that have more than one nucleus. Myofibrils are mainly found in striated muscle and are made up of actin and myosin. 3. Outline the molecular mechanism for skeletal muscle contraction. At what point is ATP used and why? In order to unattach, the myosin heads need to bind and attach to a new ATP molecule. Myosin releases actin, which breaks down ATP. This starts a new loop of actin and myosin interacting. ATP gives you a short-term boost, and when it changes into ADP, it gives you a lot of energy. 4. Explain why rigor mortis occurs. Because the body's blood is stopped, muscles need phosphagen and ATP. Although myosin moves, muscles contract because it can't unattach because it doesn't have enough ATP. This is what causes muscles to contract.

Lab 7 The Muscular System BIO201L EXPERIMENT 1: TENDONS AND LIGAMENTS Introduction Questions 1. How does the extracellular matrix of connective tissues contribute to its function? This can be done by joining cells together or dividing tissues. One example is the separation of different types of tissue. 2. Why are tendons and ligament tissues difficult to heal? Lack of nutrient and blood supply. Data and Observations 1. Label the arrows in the slide images below based on your observations from the experiment. A. Chondrocytes B. Collagen C. Collagen fiber D. Skeletal muscle fiber E. Nuclei F. Collagen fiber

Lab 7 The Muscular System BIO201L

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Lab 7 The Muscular System BIO201L Results and Discussion 1. What difference do you see between the tendon – muscle insertion image and the tendon image? In contrast to the tendon picture, which shows smooth muscle tissue with many nuclei, the photos of the tendon-muscle attachment show connective tissue that is not smooth and has a thick structure. 2. What differences do you see between the tendon and ligament sections? The ligament looks more tense and close together, while the tendon looks more spread out and far apart. There is a big difference between them in this way.

Lab 7 The Muscular System BIO201L EXPERIMENT 2: NEUROMUSCULAR JUNCTION Results and Discussion 1. Are there few or many nuclei at the end plate? Many 2. What is a motor unit? Motor neuron and the connecting muscle fibers 3. How is a greater force generated (in terms or motor unit recruitment)? As a motor nerve breaks into many other branches, they cancel each other out at different muscle fibers to make a stronger muscle power. 4. What types of sensors are present within the muscle to identify how much force is generated? Propioreceptors

Lab 7 The Muscular System BIO201L EXPERIMENT 3: MUSCLE FATIGUE Introduction Questions 1. Hypothesize what would happen if blood flow was restricted to the hand when this experiment is performed. The hand would not be able to move as if something was constricting movment Data and Observations Record your observations from the experiment in the table below, based on the instructions in the procedure. Table 1: Experimental Counts Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Predicted Value 20 20 20 20 20 Actual Value 20 20 20 15 13 Results and Discussion 1. How did the predicted results compare to the actual results? The predicted and expected numbers for 1–3 were right on the mark, but not for 4–5. 2. Did you notice any changes in the number of repetitions you could perform, or how your hand felt after each of the trials? By the third experiment my hand was very fatigued 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. Muscle contractions need ATP to power them. The two ways that it gets creatine phosphate and ADP are aerobic or anaerobic glucose metabolism. Lysic acid builds up because of this.

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Lab 7 The Muscular System BIO201L EXPERIMENT 4: GROSS ANATOMY OF MUSCULAR SYSTEM Introduction Questions 1. Label the human muscle diagram. A. Pectoralis major B. Brachioradialis C. Gracilis D. Biceps brachii E. Flexor carpi radialis- F. Deltoid G. Rectus femoris H. Tibialis anterior

Lab 7 The Muscular System BIO201L Data and Observations Record your observations from the experiment in the table below, based on the instructions in the procedure. Table 2: Gross Anatomy Data Movement Muscle(s) Activated Action(s) of Muscle(s) Forearm Extended (Step 1) Biceps brachii Flexion of forearm Fingers Extended and Splayed (Step 1) Extensor digitorum Flexion of the wrist and middle phalanges Fingers Retracted (Step 1) Extensor digitorum Relaxation of the middle phalanges Forearm Pressed Down Upon (Step 2) Extensor carpi radialis longus Extension and abduction of the wrist Elbow Bent (Step 3) Triceps brachii Elbow extensor Arm Raised to Side with Heavy Object (Step 4) Suprasupinators and deltoid prime mover of shoulder abduction Arm Extended Back with Heavy Object (Step 4) Latissimus dorsi Shoulder extension Pinching the shoulder blades Rhomboid middle trapezius Scapular adduction Shrugging Shoulders Up towards ears Upper trapezius levator scapulae Scapular elevation Raising arm above head Upper and middle trapezius Upward rotation of the scapulae Bending Wrist vertically Up Wrist extensor Wrist extension Bending Wrist vertically down Wrist flexor Wrist flexion Arms Handing down Pectoralis major Latissimus dorsi Shoulder abduction

Lab 7 The Muscular System BIO201L Results and Discussion 1. Which muscle(s) were used to extend your arms backward? Triceps brachii 2. Which muscle(s) were used to extend and splay your fingers outward? Extensor digitorum

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Lab 7 The Muscular System BIO201L EXPERIMENT 5: ATP AND MUSCULAR FATIGUE Introduction Questions 1. Explain the biochemical reasoning behind muscle fatigue. When muscles are used hard, ATP finally runs out. As the amount of ATP in the muscle drops over time, it can't keep working at the same level and speed. Data and Observations Record your observations from the experiment in the table below, based on the instructions in the procedure. Table 3: Muscle Fatigue Data Trial Time (seconds) Trial 1 30 Trial 2 20 Trial 3 13 Results and Discussion 1. What happened to the time intervals between Trial 1 and Trial 3? What caused this change? As the muscles tired, the time gap got shorter and shorter. As each try went on, tiredness slowly set in. This is because ATP turned into lactic acid when it was used up. 2. Identify three muscles which were engaged during the wall-sit. Hamstrings, Quadriceps, Hip-abductors

Lab 7 The Muscular System BIO201L EXPERIMENT 6: THE VIRTUAL MODEL - THE MUSCULAR SYSTEM (UPPER BODY) Introduction Questions 1. What is the scientific term for the muscles of the mouth? Orbicularis oris 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? Mentalis muscles located on ventral side Data and Observations Insert screenshot of the latissimus dorsi muscle:

Lab 7 The Muscular System BIO201L Insert screenshot of the greater pectoral muscle: Insert screenshot of the brachial muscle:

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Lab 7 The Muscular System BIO201L Results and Discussion 1. Which muscle is deeper in the body: the internal oblique muscle or the transverse abdominal muscle? transverse abdominal muscle 2. Is the trapezius muscle located in the abdomen, back, head, neck or thorax? Back 3. What muscle is more medial, the deltoid muscle or the greater pectoral muscle? Latissimus dorsi EXPERIMENT 7: THE VIRTUAL MODEL - THE MUSCULAR SYSTEM (LOWER BODY) Introduction Questions 1. What is the role of the long extensor muscle of the toes? Which toes does it control? Its purpose is to lift the toes up, dorsiflex the foot, and help with turning the foot in and out. It's in charge of the big toes. 2. What is an adductor muscle? List three examples of adductor muscles here. Muscles that pull body parts toward the middle line or the plane of the limbs. These are three examples: the adductor longus, the adductor brevis, and the adductor magnus.

Lab 7 The Muscular System BIO201L Data and Observations Insert screenshot of the semitendinous muscle: Insert screenshot of the soleus muscle:

Lab 7 The Muscular System BIO201L Insert screenshot of the gracilis muscle: Results and Discussion 1. Is the gracilis muscle located in the foot, hip, leg, or thigh muscle group? Thigh 2. Relate the location of the semitendinous muscle and the greater gluteal muscle. In the middle is the semitendinosus muscle. Together, they make it possible for the knees to bend and the hips to straighten. A lot of people know that the gluteus maximus muscle in the buttocks is one of the strongest and most stable bones in the body. 3. Which muscle is most distal: the pectineal muscle, the soleus muscle, or the abductor muscle of the great toe? Abductor muscle of the great toe

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Lab 7 The Muscular System BIO201L EXPERIMENT 8: FETAL PIG DISSECTION - MUSCULAR SYSTEM Introduction Questions 1. Describe the tissue that covers muscles. Fascia is the name for this tissue. Connective tissue that is made up of fibers and covers muscles. It looks shiny and white. The superficial fascia protects the muscle tissue and makes it possible for nerves and blood vessels to get to it. 2. Why are muscle fibers considered excitable? The reason for this is that action potentials are controlled by muscle contraction and are sent along the sarcolemma. 3. Why is it important to have both flexors and extensors? To allow moving in more than one way that is coordinated 4. How can muscle mass be influenced by training or age? They don't have much or any impact. The amount of protein in each muscle cell is the main factor that determines muscle growth. More protein means bigger muscles.

Lab 7 The Muscular System BIO201L Data and Observations Record your observations as stated in the experimental procedure in the table below. Ensure you provide enough to satisfy the intent of the requirements in the procedure. Submissions that do not contain the required observations as noted in the experimental procedure may be rejected. Table 4: Experimental Data Muscle Origin Insertion Movement Pectoralis major Clavicular head, medial clavicle, sternal head Lateral lip of intertubercular groove of humerus Flexion, medial rotation, horizontal adduction Latissimus dorsi Dorsal, lateral and ventral sides of the pig Fibers move anterior direction and insert in the humerus Moves foreleg dorsally and caudally Deltoids Lateral clavicle, acromion process, spine of scapula Deltoid tuberosity of humerus Abducts arm, flexion, extension, medial and lateral arm rotation Rectus abdominis Pubic crest & symphysis Cartilage of ribs 5- 7, xiphoid Flexion of vertebral column, compression of abdominal wall Transverse abdominis Inguinal ligament, iliac crest, c linea alba & pubic crest Compression of abdominal Gluteus medius Upper lateral ilium Greater trochanter of femur Abduction and medial rotation of the thigh

Lab 7 The Muscular System BIO201L Insert a high resolution photo of the fetal pig you observed in the dissection tray. Your handwritten name and access code must be clearly visible in the background. Photos that are of too low resolution, that appear inauthentic, that appear edited, or that do not show the pig, dissection tray, the data required by the procedure and a clearly written name and access code will be rejected.

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Lab 7 The Muscular System BIO201L Results and Discussion 1. How many layers of abdominal muscle are there? 4 2. What direction do the muscle fibers of the external oblique run? At a slight angel and it goes both anteriorly and inferiorly

BIO201 Lab 7

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