Understanding the Muscular System: BIO201 Lab 7 Guide

Lab 7 The Muscular System BIO201L Student Name: Ani Harutyunyan Access Code (located on the lid of your lab kit): AC-BX89CU Lab Report Format Expecta0ons U"lize college level grammar and professional forma4ng when comple"ng this worksheet. Submissions without proper forma4ng, all required photos or suﬃcient responses will be rejected. Pre- lab Ques,ons 1. How do banding pa:erns change when a muscle contracts? The sarcomeres, which contain acDn and myosin filaments, undergo structural changes as these filaments slide past each other. 2. What is the difference between a muscle organ, a muscle fiber, myofibril and a myofilament? A muscle organ is a complex structure consisDng of muscle Dssue, blood vessels, nerves, and connecDve Dssue. At its core, the muscle is composed of individual muscle fibers, or cells. Inside these fibers are cylindrical myofibrils. The sarcomeres within the myofibrils are made up of individual protein strands known as myofilaments. 3. Outline the molecular mechanism for skeletal muscle contracDon. At what point is ATP used and why? Skeletal muscle contracDon involves excitaDon-contracDon coupling, iniDated by calcium release, leading to myosin and acDn cross-bridge formaDon. This triggers the power stroke and sliding filament mechanism, causing sarcomere shortening. ATP provides the essenDal energy for contracDon and muscle relaxaDon, as it fuels the contracDon cycle and aids in calcium reabsorpDon and tropomyosin reblocking of acDn sites. 4. Explain why rigor morDs occurs. Rigor morDs, the sDffening of muscles aUer death, occurs due to biochemical alteraDons in muscle fibers. This condiDon develops when myosin heads remain a:ached to acDn in the absence of ATP, forming cross-bridges that cause muscle sDffness.

Lab 7 The Muscular System BIO201L EXPERIMENT 1: TENDONS AND LIGAMENTS Introduc,on Ques,ons 1. How does the extracellular matrix of connecDve Dssues contribute to its funcDon? The extracellular matrix serves mulDple funcDons, including offering structural support, facilitaDng cell interacDons, guiding Dssue growth and healing, conveying mechanical signals, and preserving growth factors to regulate cellular acDviDes. 2. Why are tendons and ligament Dssues diﬃcult to heal? Tendons and ligaments present challenges in the healing process because of factors like their sparse blood supply, reduced metabolic acDvity, exposure to mechanical stress, and the formaDon of scar Dssue, all of which impede the delivery of nutrients necessary for recovery.

Lab 7 The Muscular System BIO201L Data and Observa,ons 1. Label the arrows in the slide images below based on your observaDons from the experiment. A. Chondrocytes B. Collagen C. Collagen fiber D. Skeletal muscle fiber E. Nuclei F. Collagen fiber G.

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Lab 7 The Muscular System BIO201L

Lab 7 The Muscular System BIO201L Results and Discussion 1. What difference do you see between the tendon – muscle inserDon image and the tendon image? In the image of the tendon muscle, the collagen appears wrinkled, which is different from the smoother appearance observed in the image of the tendon & the fibers in the tendon appear to be consistently aligned in a single direcDon, unlike the varied orientaDon seen in the tendon- muscle inserDon area. 2. What differences do you see between the tendon and ligament secDons? Tendon fibers are densely packed in Dght bundles In contrast to the less Dghtly organized fibers found in ligaments. Likewise, there is a significant presence of collagen fibers within skeletal muscle fibers, although they are not as Dghtly packed.

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 units, integral components of the neuromuscular system, comprise a motor neuron and the muscle fibers it is linked to. They serve a major funcDon in muscle contracDon and motor control, serving as the fundamental funcDonal units of this system. 3. How is a greater force generated (in terms or motor unit recruitment)? The magnitude of muscle force relies on the acDvaDon of motor units, considering both their quanDty and size. This acDvaDon follows the size principle, wherein motor units are recruited in a systemaDc fashion based on their size and the level of sDmulaDon required for acDvaDon. 4. What types of sensors are present within the muscle to idenDfy how much force is generated? Muscle spindles and Golgi tendon organs, acDng as sensory receptors within muscles, monitor parameters like muscle length, stretching, and tension, providing informaDon about the generated force. They are involved in regulaDng and adjusDng muscle force during different acDviDes.

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Lab 7 The Muscular System BIO201L EXPERIMENT 3: MUSCLE FATIGUE Introduc,on Ques,ons 1. Hypothesize what would happen if blood ﬂow was restricted to the hand when this experiment is performed. In this scenario, I may experience reduced sensaDon in my hand and decreased muscle coordinaDon, which could hinder my ability to successfully complete the experiment. Data and Observa,ons Record your observaDons from the experiment in the table below, based on the instrucDons in the procedure. Table 1: Experimental Counts Results and Discussion 1. How did the predicted results compare to the actual results? I began with higher expectaDons in trial 1 and progressively lowered them, anDcipaDng that muscle faDgue would result in lower trial numbers as Dme passed. However, contrary to this assumpDon, the actual results indicated that the trial values remained consistent throughout. 2. Did you noDce any changes in the number of repeDDons you could perform, or how your hand felt aUer each of the trials? In each trial, I kept the repeDDon count constant, but as the trials advanced, I started experiencing heightened sensaDons during the exercises, and my hand began to exhibit mild soreness. 3. Explain the acDons that were occurring at the cellular level to produce this movement. Include sources of energy and any possible effect of muscle faDgue. Muscle faDgue occurs when ATP and energy reserves are depleted. As the test conDnued, each repeDDon became progressively more diﬃcult due to declining ATP levels. AddiDonally, the buildup of lacDc acid and reduced oxygen levels are key factors contribuDng to muscle exhausDon. Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Predicted Value 18 16 14 12 10 Actual Value 14 14 14 14 14

Lab 7 The Muscular System BIO201L EXPERIMENT 4: GROSS ANATOMY OF MUSCULAR SYSTEM Introduc,on Ques,ons 1. Label the human muscle diagram. A. Pertoralis major B. Brachioradialis C. Vastus medialis D. Biceps brachii E. Extensor carpi F. Deltoid G. Rectus femoris H. Tibalis anterior

Lab 7 The Muscular System BIO201L Data and Observa,ons Record your observaDons from the experiment in the table below, based on the instrucDons in the procedure. Table 2: Gross Anatomy Data Movement Muscle(s) Ac,vated Ac,on(s) of Muscle(s) Forearm Extended (Step 1) Triceps brachii Extends elbow and shoulders Fingers Extended and Splayed (Step 1) Extensor digitorum Moves/extends the fingers Fingers Retracted (Step 1) Flexor digitorum Retracts the fingers Forearm Pressed Down Upon (Step 2) Quadratus and pronator teres Allows you to press down on the forearm Elbow Bent (Step 3) Brachialis Flexes the elbow Arm Raised to Side with Heavy Object (Step 4) Trapezius, deltoid supraspinatus, serratus Shoulder ﬂex Arm Extended Back with Heavy Object (Step 4) Triceps brachii Flexes/extends arm (lower limbs; student selects ac3on…) Semimembranosus, popliteus muscle, biceps femoris Knee ﬂexion (lower limbs; student selects ac3on…) Externus, obturator, gluteus medius, gluteus minimus Moves thigh away from pelvis, outward (lower limbs; student selects ac3on…) Extensor halluces longus, extensor digitorum longus Pull the foot up (lower limbs; student selects ac3on…) Extensor halluces longus, extensor digitorum longus Turn foot outward laterally (lower limbs; student selects ac3on…) Fibularis longus and fibularis brevis Move the food so soles of the feet are facing toward midline

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Lab 7 The Muscular System BIO201L (lower limbs; student selects ac3on…) Tibialis posterior and Ybialis anterior Rotate thigh (lower limbs; student selects ac3on…) Biceps femoris, gluteus and sartorius Rotate the knee joint Movement Muscle(s) Ac,vated Ac,on(s) of Muscle(s)

Lab 7 The Muscular System BIO201L Results and Discussion 1. Which muscle(s) were used to extend your arms backward? Triceps brachii & Posterior deltoid 2. Which muscle(s) were used to extend and splay your fingers outward? - Extensor muscles (located in the forearm) -interosseous muscles (found in the hand)

Lab 7 The Muscular System BIO201L EXPERIMENT 5: ATP AND MUSCULAR FATIGUE Introduc,on Ques,ons 1. Explain the biochemical reasoning behind muscle faDgue. Muscle faDgue occurs when ATP and energy reserves are depleted. As the test conDnued, each repeDDon became progressively more diﬃcult due to declining ATP levels. AddiDonally, the buildup of lacDc acid and reduced oxygen levels are key factors contribuDng to muscle exhausDon. Data and Observa,ons Record your observaDons from the experiment in the table below, based on the instrucDons in the procedure. Table 3: Muscle FaFgue Data Results and Discussion 1. What happened to the Dme intervals between Trial 1 and Trial 3? What caused this change? The Dme between the trials was shortened due to faDgue, resulDng in muscle soreness and discomfort. 2. IdenDfy three muscles which were engaged during the wall-sit. -hamstrings -quadriceps femoris -gluteus maximus Trial Time (seconds) Trial 1 57 Trial 2 44 Trial 3 30

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Lab 7 The Muscular System BIO201L EXPERIMENT 6: THE VIRTUAL MODEL - THE MUSCULAR SYSTEM (UPPER BODY) Introduc,on Ques,ons 1. What is the scienDfic term for the muscles of the mouth? orofacial muscles (muscles of masYcaYon) 2. What is the scienDfic name of the muscle that facilitates the raising of the lower lip? Is it on the ventral or dorsal side of the body? The Mentalis muscle Data and Observa,ons Insert screenshot of the laDssimus dorsi muscle:

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

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? The transverse abdominal muscle 2. Is the trapezius muscle located in the abdomen, back, head, neck or thorax? Posterior neck region 3. 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) Introduc,on Ques,ons 1. What is the role of the long extensor muscle of the toes? Which toes does it control? The role of the long extensor muscle of the toes includes extending and aligning both the big toe and the four smaller toes. 2. What is an adductor muscle? List three examples of adductor muscles here. An adductor muscle is responsible for moving body parts closer to the body's midline, with examples including the adductor magnus, adductor braves, and adductor longus.

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Lab 7 The Muscular System BIO201L Data and Observa,ons 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? leg 2. Relate the locaDon of the semitendinous muscle and the greater gluteal muscle. While both part of the musculature of the lower body, the semitendinosus muscle is situated in the posterior thigh, while the gluteal muscle is found in the bu:ocks or gluteal region. 3. Which muscle is most distal: the pecDneal muscle, the soleus muscle, or the abductor muscle of the great toe? abductor muscle

Lab 7 The Muscular System BIO201L EXPERIMENT 8: FETAL PIG DISSECTION - MUSCULAR SYSTEM Introduc,on Ques,ons 1. Describe the Dssue that covers muscles. Fascia, a form of connecDve Dssue, surrounds and protects muscles, providing structural support and facilitaDng seamless movement. 2. Why are muscle fibers considered excitable? Because of their ability to respond to both electrical and chemical sDmuli. 3. Why is it important to have both ﬂexors and extensors? Because they both are crucial for coordinated body movement. 4. How can muscle mass be inﬂuenced by training or age? Muscle mass can be inﬂuenced by training and age. Regular exercise and strength training can enhance muscle mass, while aging oUen leads to a decline in muscle mass, a condiDon referred to as sarcopenia.

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Lab 7 The Muscular System BIO201L Data and Observa,ons Record your observaDons as stated in the experimental procedure in the table below. Ensure you provide enough to saDsfy the intent of the requirements in the procedure. Submissions that do not contain the required observaDons as noted in the experimental procedure may be rejected. Table 4: Experimental Data Muscle Origin Inser,on Movement Pectoralis major Clavicular head and breast plate Long bone of the upper arm and the bicipital groove RotaYon & abducYon LaYssimus dorsi Thoracis t7-t12, iliac crest and the inferior angle of the scapula Floor of the intertubercular groove of the humerus AdducYon, extension & rotaYon Deltoids Clacicle and shoulder blade Long bone of upper arm RotaYon, ﬂexion, extension, abducYon Rectus abdominis Pubic crest, symphysis and pubic Xiphoid processes and ribs 5-7 Flexion Transverse abdominis Costal carYlage of ribs 7-12, thoracolumbar fascia, anterior of iliac crest, and iliopecYneal arch Linea alba, oblique muscle, pubic crest, and pubis Compression Gluteus medius Gluteal surface of ilium, gluteus maximus Greater trochanter of femus AbducYon, ﬂexion, rotaYon

Lab 7 The Muscular System BIO201L Insert a high resoluDon photo of the fetal pig you observed in the dissecDon tray. Your handwriKen name and access code must be clearly visible in the background. Photos that are of too low resoluDon, that appear inauthenDc, that appear edited, or that do not show the pig, dissecDon tray, the data required by the procedure and a clearly wri:en name and access code will be rejected.

Lab 7 The Muscular System BIO201L Results and Discussion 1. How many layers of abdominal muscle are there? The abdominal muscles consist of three primary layers: the rectus abdominis, external obliques, and internal obliques. In addiDon, the deepest layer, known as the transverse abdominis, encircles the abdomen. 2. What direcDon do the muscle fibers of the external oblique run? The muscle fibers of the external oblique run diagonally, descending inward.

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BIO201 Lab 7

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