EXERCISE 11 Microscopic Anatomy and Organization of Skeletal Muscle
Time Allotment: 1½ hours.
Multimedia Resources: See Appendix B for Guide to Multimedia Resource Distributors.
See Exercise 5 for histology listings. Human Muscul Musculature ature video (PE: 23 minutes , Cadaver Cadaver Dissecti Dissection on Video Video Series Series for Human Anatomy Anatomy and Physiology DVD) Interactive Physiology® 10-System Suite: Muscular System (PE: CD-ROM, Website) Muscles and Joints: Muscle Power (FHS: (FHS: 26 minutes, DVD, 3-year streaming webcast) The New Living Body: Muscles (FHS: 20 minutes, DVD, 3-year streaming webcast) Practice Anatomy Lab™ 3.0 (PAL) (PE: DVD, Website)
Solutions: Saline Solution, 0.9% Weigh out 0.9 gram of NaCl. Add distilled water to a final volume of 100 milliliters.
Laboratory Materials Ordering information is based on a lab size of 24 students, working in groups of 4. A list of supply house addresses appears in Appendix A.
Fresh chicken breast or thigh 6–12 dropper bottles of physiologic saline (mammalian, 0.9%) 3-D models of skeletal muscle cells (if available) 24 compound microscopes, lens
paper, lens cleaning solution Microscope slides and coverslips 24 forceps 48 dissecting needles 24 slides of skeletal muscle (longitudinal and crosssectional views) and skeletal
muscle showing neuromuscular junction 3-D model of skeletal muscle showing neuromuscular junctions junctions (if available) available)
Advance Preparation
1. Purchase chicken chicken breasts or thighs from the meat market (one per lab). Refrigerate until used. Cut or tear the meat into small strips just before the lab. Provide gloves. 2. Set out forceps, dissecting dissecting needles, needles, 0.9% saline solution in dropper bottles, and microscope slides and coverslips for each student. Designate an organic matter disposal area. 3. Set out prepared slides of skeletal muscle (longitudinal and cross-sectional views) and slides Copyright © 2014 Pearson Education, Inc.
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showing neuromuscular (myoneural) junctions. (Because the latter slides are expensive, a demonstration microscope is an alternative to providing a slide for each student.) Set out lens paper and lens cleaning solution. Have compound microscopes available. 4. Set out any available models of skeletal muscle cells and neuromuscular junctions.
Comments and Pitfalls
1. Students may have difficulty observing observing the muscle banding pattern. This is usually because the light intensity is set too high and the iris diaphragm is not closed down. 2. Emphasize the importance of understanding the organization and terminology of muscle structure. The organization and terminology of the nerves are very similar.
Answers to Pre-Lab Quiz (p. 171)
1. c, It is one of the major components of hollow organs.
6. b, a tendon tendon
2. fibers fibers
8. True True
3. True True
9. sarcome sarcomere re
4. actin, myosin
7. neuromuscular neuromuscular (myoneural) (myoneural) junction
10. 10. Fals Falsee
5. b, endomysium endomysium
Answers to Activity Questions Activity 1: Examining Skeletal Muscle Cell Anatomy (p. 174)
4. The banding pattern pattern and limits of the cells are much clearer clearer on the prepared slides. slides.
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REVIEW SHEET EXERCISE 11 Microscopic Anatomy and Organization of Skeletal Muscle
Name________________________ Lab Time/Date________ Time/D ate____________ _________ ______ _ Skeletal Muscle Cells and Their Packaging into Muscles 1. Use the terms in the key to correctly identify the structures described below. Not all terms will be used. g; perim pe rimysi ysium um
1. connective connective tissue tissue covering covering a bundle of muscle muscle cells cells
c; fascicl fas ciclee
2. bundl bundlee of muscl musclee cells cells
Key:
a. endomysium b. epimysium
i; sarc s arcome omere re
3. contrac contractile tile unit of muscl musclee
d; fiber fib er
4. a mus muscl clee cel celll
d. fiber
a; endom en domysi ysium um
5. thin areolar areolar connective connective tissue tissue investing investing each each muscle muscle cell
e. myofibril
h; sarco sa rcolemm lemma a
6. plasma plasma membr membrane ane of the the muscle muscle fiber fiber
f. myofilament
e; myofibr myo fibril il
7. a long filamentous filamentous organelle with a banded banded appearance appearance found within muscle cells
f; myofilament k; ten t endo don n
8. actinactin- or myosin-co myosin-contai ntaining ning structu structure re
c. fascicle
g. perim rimysium ium h. sar sarcolem lemma i.
sarcomere
j.
sarcoplasm sarcoplasm
9. cord of collagen fibers that that attaches attaches a muscle muscle to a bone
2. List three reasons the connective tissue wrappings of skeletal muscle are important. The connective connective tissue wrappings wrappings (1) bundle the muscle fibers together, increasing increasing coordination coordination of their activity; (2) add strength to the muscle; and (3) provide a route for entry and exit of blood vessels and nerves to the muscle fibers.
3. Why are there more indirect—that is, tendinous—muscle attachments to bone than there are direct attachments? They conserve space (less bulky than fleshy muscle attachments) and are more durable than muscle tissue where bony prominences must be spanned.
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4. How does an aponeurosis aponeurosis differ differ from a tendon tendon structu structurall rally? y? An aponeurosis is a sheet of white fibrous connective tissue; a tendon is a band or cord of the same tissue.
How is an aponeurosis functionally similar to a tendon? Both serve to attach a ttach muscles to bones or to other muscles.
5. The diagram illustrates a small portion of several myofibrils. Using letters from the key, correctly identify each structure indicated by a leader line or a bracket. Key: a. A band b. actin filament c. I band
d. myosin filament e. T tubule f. terminal cistern
g. triad h. sarcomere i. Z disc
6. On the following figure, label a blood vessel, endomysium, epimysium, a fascicle, a muscle cell, perimysium, and the tendon.
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The Neuromuscular Junction 7. Complete the following statements:
The junction between a motor neuron’s terminal bouton and the muscle cell membrane is called a 1 junction. junction. A motor neuron and all all of the skeletal skeletal muscle cells it stimulates stimulates is called called a 2 . The actual actual gap betwee between n the terminal terminal bouton bouton and and the muscle muscle cell is called called a 3 . Within Within the terminal terminal bouton bouton are many many small small vesicl vesicles es contai containing ning a neurot neurotrans ransmit mitter ter substan substance ce called called 4 . When the the 5 reaches reaches the ends ends of the axon, the neurotr neurotrans ansmitt mitter er is released released and diffuses diffuses to the muscle cell membrane to combine with receptors there. The combining of the neurotransmitter with the muscle membrane receptors causes the membrane to become permeable to both sodium and potassium. The greater greater influx influx of sodium sodium ions results results in 6 of the membran membrane. e. Then contrac contraction tion of the muscle muscle cell cell occurs. 1. neuromuscular or myoneural 2. motor unit 3. synaptic cleft 4. acetylcholine 5. action potential (nerve impulse) 6. depolarization
Key:
a. mito mitoch chon ondr drio ion n 8. The events that occur at a neuromuscular junction are depicted below. Identify by labeling every structure provided with a leader line. b. muscl scle fib fibeer c. myel myelin inat ated ed axon axon d. syna synapt ptic ic clef cleftt e. term termin inal al bout bouton on Copyright © 2014 Pearson Education, Inc.
f. T tubule g. vesicl vesiclee conta contain ining ing ACh ACh
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