Chapter 10- Skeletal Muscle Tissue

Question 1

Muscle Functions

Muscle tissue has the following functions:

Answer 1

1. Movement: Skeletal muscle attaches to the skeleton and moves the body by moving the bones.
2. Maintenance of posture: Certain skeletal muscles contract continuously to maintain posture, enabling the body to remain in a standing or sitting position.
3. Joint stabilization: Muscle tone is a constant, low level of contractile force that is generated by a muscle even when it is not causing movement. Muscle tone stabilizes joints by keeping tension on the muscle tendons that cross over joints just external to the joint capsule.
4. Heat generation: Muscle contractions produce heat that plays a vital role in maintaining normal body temperature at 98.6°F (37 °C).

Question 2

Muscle’s Special Characteristics

Muscle tissue has some special functional characteristics that distinguish it from other tissues:

Answer 2

1. Contractility
2. Excitability
3. Extensibility
4. Elasticity

Question 3

Muscles Special Characteristics

1. Contractibility
2. Excitability
3. Extensibility
4. Elasticity

Answer 3

1. Contractibility: muscle cells shorten and generate a strong pulling force as they contract.
2. Excitability: Nerve signals or other factor excite muscle cells, causing electrical impulses to travel along the cells’ plasma membrane, causing the cells to contract.
3. Extensibility: Muscle tissue can be stretched by the contraction of an opposing muscle.
4. Elasticity: After being stretched, muscle tissue can recoil passively and resume its resting length.

Question 4

Types of Muscle Tissue

What are the three types of muscle tissue?

Answer 4

1. skeletal
2. cardiac
3. smooth

Question 5

Types of Muscle Tissue

Each type of can be characterized by how many features?

What are they?

Answer 5

• Each type can be characterized by two main features:
  
  1. the presence or absence of striations in the muscle cells.
  2. whether control is voluntary or involuntary.

Question 6

Striated vs. Non-striated

• Striated muscle tissue has stripes extending _1.____ across the muscle cells.
• Nonstriated muscle… _{2._____}

Answer 6

1. transversely
2. …does not have these distinctive bands.

Question 7

Voluntary vs. Involuntary

• Voluntary and involuntary refer to the _1.____ of the muscle tissue.
• What does voluntary muscle do?
• What does involuntary muscle do?

Answer 7

1. innervation

• Voluntary: innervated by voluntary motor nerves ad subject to conscious control; you can control this muscle tissue at will.
• Involuntary: innervated by the involuntary portion of the nervous system and cannot be controlled consciously.

Question 8

Muscle Tissue Types

What’s the structure and function of Skeletal muscle tissue?

Answer 8

• Located in the skeletal muscles, discrete organs that attach to and move the skeleton
• Make up 40% of the body weight
• Cells are striated
• Contraction is subject to voluntary control

Question 9

Muscle Tissue Types

Explain cardiac muscle tissue and its function?

Answer 9

• Occurs only in the walls fo the heart
• Cells are striated
• Contractions are subject to involuntary control

Question 10

Muscle Tissue Types

Explain Smooth muscle tissue and the function?

Answer 10

• Most found in the walls of hollow internal organs
• Cells lack striations
• Contractions are subject to involuntary control

Note: Cardiac and smooth muscle tissues are visceral muscle.

Question 11

What are the similarities among the three different muscle tissue types?

Answer 11

1. The cells of skeletal and smooth muscle tissue (only) are called fibers because they are elongated.
2. In all three, muscle contraction depends on myofilaments.. specific types of microfilaments that are responsible for the shortening of muscle cells.
3. The plasma membrane of muscle cells is called a sarcolemma and the cytoplasm is called sarcoplasm
   
   • Despite the different terms, the membranes and cytoplasm of muscle cells are not fundamentally different from those of other cell types.

Question 12

C.T. and Fascicles

Several sheaths of C.T. hold the fibers of a skeletal muscle together, and they are called?

Answer 12

• From external –> internal:
  
  • Epimysium
  • Perimysium
  • Endomysium

Question 13

What is the Epimysium?

What is the Perimysium?

What is the Endomysium?

Answer 13

• Epimysium(“outside the muscle”): an overcoat of dense, irregular C.T. that surrounds the whole skeletal muscle.
• Perimysium (“around the muscle”): a layer of fibrous C.T. that surrounds each fascicle (a group of muscle fibers)
• Endomysium (“within the muscle”): a fine sheath of C.T. consisting mostly of reticular fibers that surround each muscle fiber within each fascicle.

Question 14

These fibrous connective tissues ____1. muscle fibers together and ____2. them in parallel alignment so they can work together to produce ____3.

what are they?

Answer 14

1. bind
2. hold
3. force
   - Epimysium, perimysium, endomysium

Question 15

-Epimysium, Perimysium, Endomysium

All 3 sheaths are____1. with the ____2. , the connective tissue structure that joins skeletal ____3. to ____4.

Answer 15

1. continuous
2. tendons
3. muscles
4. bones

Question 16

When muscle fibers ____1., they pull on the surrounding ____2... because of the ____3. between sheaths, this pull is then exerted on the perimysium, epimysium, and tendon.

-The sheaths also provide a muscle with much of its ____4. and carry the blood vessels and nerves that serve the muscle ____​5.

Answer 16

1. contract
2. endomysium
3. continuity
4. elasticity
5. fibers

Question 17

• In general, each skeletal muscle is ____1. by one nerve, one artery and ____2... all of which enter or exit the muscle near the ____3. of its length.
  
  • The nerves and vessels ____4. repeatedly in the intramuscular C.T., with the smallest branches serving individual muscle ____​5.

Answer 17

1. supplied
2. one or more veins
3. middle
4. branch
5. fibers

Question 18

• ____1. form a network within the ___₂.
  
  • The rich blood supply to muscles ____3. the high demand that contracting muscle fibers have for ___ _4. and oxygen.
• The ____5. nerve branches serve individual muscle fibers
  
  • ____6. junction: interface between nerve and muscular fiber.

Answer 18

1. Capillaries
2. endomysium
3. reflects
4. nutrient
5. smallest
6. neuromuscular

Question 19

• A muscle ____1. is the location on a bone where a ____2. connects to the bone.
  
  • Each skeletal muscle ____3. from one bone to another… crossing at least one moveable ____​4.

Answer 19

1. attachment
2. muscle
3. extends
4. joint

Question 20

• When a muscle ____1., it causes one of the bones to move while the other bone usually remains ____2..
  
  • The ____3. of the muscle on the less moveable bone is called the ____4. of the muscle… whereas the attachment on the more moveable bone is called the muscle’s ___₅.
  • Thus, when the muscle ____6., its insertion is ____7. toward its origin.

Answer 20

1. contracts
2. fixed
3. attachment
4. origin
5. insertion
6. contracts
7. pulled

Question 21

• In the muscles of the ___₁. , the origin is the more ___₂. attachment of the muscle and the insertion is the more ___₃. attachment.
• NOTE: the origin and insertion of a given muscle can be at ___ ₄. attachment of the muscle, depending on
  
  • What ____5. the body is in
  • The ____6. produced as the muscle ____₇.

Answer 21

1. limbs
2. proximal
3. distal
4. either
5. position
6. movement
7. contracts

Question 22

• Muscles attach to their origins and insertions via the strong fibrous ____1. of the bone.
  
  • In ____2., or fleshy attachments, the attaching strands of the C.T. are so short that the muscle ____3. themselves appear to attach directly to the ___₄.
  • In indirect attachments, the C.T. ____5. well beyond the end of the muscle fibers to form either a cordlike _____6. or a flat sheet called ____ ₇.

Answer 22

1. periosteum
2. direct
3. fascicles
4. bone
5. extends
6. tendon
7. aponeurosis

Question 23

• Indirect attachments are more _____1. than direct attachments, and most muscles have ___₂.
  
  • Raised bone _____3. are often present where tendons _____4. bones (e.g. Greater Trochanter)

Answer 23

1. common
2. tendons
3. markings
4. meet

Question 24

• Skeletal muscle ____1. are long, cylindrical cells
  
  • Diameter: ___-____2. um
  • Length: Several cm (short muscles)–> Dozens of cm(_____3. muscles)
• Each muscle fiber is formed by the _____4. of hundreds of _____5. cells. Because the fibers develop this way, they contain many _____6., which lie in the periphery of each fiber, just deep to the _____​7.

Answer 24

1. fibers
2. 10-100
3. long
4. fusion
5. embryonic
6. nuclei
7. sarcolemma

Question 25

* The \_\_\__1. of skeletal muscle fibers are the result of the internal structure of long, _2.\_\_\_\_ \_\_\_\_\_s called myofibrils. * Myofibrils are specialized \_\_\__3. organelles unique to muscle tissue that make up more than \_\_% of the \_\_\_₅. * A myofibril is a long row of repeating \_\_\__6. called sarcomeres (muscle segments) * a \_\_\__​7. is the _basic unit of contraction._

Answer 25

1. striations 2. rod-shaped organelles 3. contractile 4. 80% 5. sarcoplasm 6. segments 7. sarcomere

Question 26

* The boundaries at the two ends of each sarcomere are called \_\_\__1. (or Z-lines) * Attached to each Z-disc and extending \_\_\__2. the center of the sarcomere are many fine \_\_\_ _3. called thin(\_\_\__4.) filaments, which consist primarily of the protein actin. * In the \_\_\__5. of the sarcomere and overlapping the inner ends of the thin filaments is a cylindrical bundle of thick(\_\__6.) filaments, which consist primarily of myosin \_\_₇. * Also contain \_\_\_ _8. enzymes that split ATP to \_\__9. the energy required for muscle \_\_ ₁₀.

Answer 26

1. Z-discs 8. ATPase 2. toward 9. release 3. myofilaments 10. contraction 4. actin 5. center 6. myosin 7. molecules

Question 27

* The ***sarcomere \_\_\__1.*** explains the pattern of ***\_\_\_***_2. in skeletal muscle fibers. * The _3.\_\_ \_\_\_s are created by the full length of the thick filaments in the sarcomeres, along with the inner ends of the thin filaments. * This region is called the ***\_\_***_4. * The central part of an A band, where \_\__5. thin filaments reach, is the **\_\_\_**_​6.

Answer 27

1. structure 2. striations 3. dark bands 4. A band 5. no 6. H zone

Question 28

* Each skeletal muscle fiber contains \_\_\__1. sets of **\_\_**_2. that participate in the regulation of muscle \_\_\__3.: * ***Sarcoplasmic reticulum (SR)*** * ***T tubules*** * ***Sarcoplasmic reticulum(SR***): an elaborate smooth \_\_\__4. reticulum whose interconnection \_\_\__5. surround each myofibril and run longitudinally along the \_\_\__​6.

Answer 28

1. two 2. tubules 3. contraction 4. endoplasmic 5. tubules 6. myofibril

Question 29

* ___ \_\_\__1. ("end sacs"): larger perpendicular \_\_\__2. over the junction between the A bands and _ \_\_\_ _3..

Answer 29

1. terminal cisternae 2. cross-channels 3. I bands

Question 30

* The SR \_\__1. large quantities of __ \_\__2. (Ca²⁺)^, which are released when the muscle is stimulated to contract. * Ca²⁺ ions \_\_\__3. through the \_\_\__4. to the thin filaments, where they trigger the __ \_\__5. mechanism of contraction. * After the contraction, the Ca²⁺ ions are pumped back into the \_\__​6. for storage. * Contracts- release calcium * Relaxed- actively transport calcium back in

Answer 30

1. stores 2. calcium ions 3. diffuse 4. cytosol 5. sliding filament 6. SR

Question 31

* Muscular contraction in skeletal muscle is controlled by \_\_\_-\_\_\_ _1. impulses that travel along the \_\_\_ _2. of the muscle cell. * These impulses are further conducted by the \_\_ _3., deep \_\_\_ _4. of the sarcolemma that run between each pair of \_\_\_ _5. cisternae of the sarcoplasmic reticulum.

Answer 31

1. nerve-generated 2. sarcolemma 3. T Tubule 4. invaginations 5. terminal

Question 32

* Because T tubules are \_\__1. of the \_\_\__2., they conduct each impulse to the \_\_\__3. regions of the muscle \_\_\_ _4. * The complex of a T tubule that's flanked by two terminal cisternae at each \_\_\__5. is called a \_\_\_ _6. ("group of three")

Answer 32

1. continuations 2. sarcolemma 3. deepest 4. fiber 5. A-I junction 6. triad

Question 33

* There are \_\__1. types of muscle contraction involved in producing \_\_\_₂. * \_\_\__3. contraction: it shortens and does work * \_\_\__4. contraction: a muscle generates force as it \_\_\__5.; essential for controlled movement and resistance to \_\_\__​6.... when muscles are acting "like a \_\__7." they are contracting eccentrically (landing from a jump)

Answer 33

1. two 2. movement 3. Concentric 4. Eccentric 5. lengthens 6. gravity 7. brake

Question 34

* Concentric contractions of skeletal muscle is explained by the ____ \_\_\_\_ \_\_\_\_₁. * Contraction results as the myosin \_\__2. of the \_\_\__3. filaments attach to the thin filaments at both ends of the \_\_₄ and \_\_₅ the thin filaments toward the sarcomere by ___ \_\_\__​6.

Answer 34

1. sliding filament mechanism 2. heads 3. thick 4. sarcomere 5. pull 6. swiveling inward.

Question 35

* After a myosin head \_\_₁ at its "hinge," it lets go, returns to its original position, \_\_₂ to the \_\_₃ filament farther along its \_\_₄, and pivots again. * This ratchet-like cycle is repeated many times during a single contraction. * Note: the thick and thin filaments do not \_\_₅.. they merely \_\_₆ past one another.

Answer 35

1. pivots 2. binds 3. thin 4. length 5. shorten 6. slide

Question 36

* The sliding filament mechanism is initiated by the ₁\_\_ of\_\_\_⁺ ions from the SR and the binding of those ions to the \_\_₂ filaments. * This process is powered by \_\_\_₃. * The action of the thick filaments pulls the two \_\_\_\_4 closer together, causing each sarcomere to \_\_\_₅... * causing the I bands to shorten * causing the H zone to disappear completely * Note: the A bands stay the same length because the length of the \_\__​6 filaments does not change.

Answer 36

1. release of Ca²⁺ 2. thin 3. ATP 4. Z discs 5. shorten 6. thick

Question 37

* The optimal \_\_₁ length for skeletal muscle fibers is the length that will generate the greatest \_\_₂ force when the muscle is \_\_₃. * This \_\_₄ length occurs when a fiber is \_\_\_₅ stretched.. so that its thin and thick filaments \_\_\__​6 only to a moderate extent.

Answer 37

1. resting 2. pulling 3. contracted 4. optimal 5. slightly 6. overlap

Question 38

* Whole skeletal muscles have a \_\_₁ of optimal operational length that runs from about ₂\_\_% of their \_\_\_₃ resting length to about ₄\_\_% of that length. * \_\_₅ normally do not let any bone move so widely that its \_\_ ₆ muscles could not shorten or stretch beyond their optimal range.

Answer 38

1. range 2. 80 3. normal 4. 120 5. Joints 6. attached

Question 39

* ***Titin:*** a \_\_ ₁ molecule in \_\_ ₂ that resists \_\_\_₃. * The titin molecules in a sarcomere \_\_ ₄ from the \_\_₅ to the thick filament and run within the thick filament to attach to the \_\_\_ ₆. * **_Two basic functions_**: * \_\_₇ the thick filaments in place in the sarcomere * \_\_ ₈ when the muscle is being stretched, then \_\_ ₉ when the stretching force is released.. contributing to muscle \_\_ ₁₀.

Answer 39

1. spring-like 7. holds 2. sarcomeres 8. unfolds 3. overstretching 9. refolds 4. extend 10. elasticity 5. Z disc 6. M line

Question 40

* Cardiac muscle is the muscle tissue of the\_\_₁ wall. * Forms a thick layer called \_\_₂ * Contractions of cardiac muscle __ \_\_₃ through the blood vessels of the \_\_₄ system. * Cardiac muscle is striated like skeletal muscle, and it contracts through the \_\__​5 filament mechanism.

Answer 40

1. heart 2. myocardium 3. pump blood 4. circulatory 5. sliding

Question 41

* Cardiac muscle cells are \_\_₁ cells (not fused cell colonies like skeletal muscle fibers)\_\_₂ from one another by a delicate \_\_\_₃ ***(CT).*** * Each cell contains **one** or **two \_\_₄** in its \_\_₅, not at the periphery. * NOTE: Cardiac muscle cells are not called fibers. * Unique to cardiac muscle, its cells \_\_₆ and join together at ___ \_\_\_₇ called \_\_₈ discs... so that they form cellular \_\_\__​9.

Answer 41

1. single 8. intercalated 2. seperated 9. networks 3. endomysium 4. nuclei 5. center 6. branch 7. complex junctions

Question 42

* Intercalated discs have a combination of \_\_₁ types of cell \_\_₂: 1. Desmosomes 2. Fasciae adherans: long, \_\_-\_\_ ₃ junctions 3. Gap junctions * \_\_ ₄ and \_\_₅ hold the cells together, whereas the __ \_\_₆ allow ions to pass between \_\_\_ ₇.

Answer 42

1. three 2. junctions 3. desmosome-like 4. Desmosomes 5. Fasciae adherans 6. gap junction 7. cells

Question 43

* Most smooth muscle of the body is found in the \_\_₁ of \_\_₂ ***organs***... they contract via the **\_\_₃ filament mechanism.** * **_Six major locations_**: 1. inside the \_\_₄, and in the \_\_₅ of the 2. circulatory \_\_₆, 3. \_\_₇ vessels, 4. \_\_₈ tubes, 5. \_\_₉ organs, 6. \_\_₁₀ organs.

Answer 43

1. walls 8. digestive 2. viceral 9. urinary 3. sliding 10. reproductive 4. eye 5. walls 6. vessels 7. respiratory

Question 44

* Each \_\_₁ muscle fiber is a spindle-shaped cell, with \_\_₂ centrally located nucleus. Cells are separated by \_\_₃. * smooth muscle fibers have no striations or \_\_₄. * \_\_₅ thick and thin filaments fill much of the \_\__​6.

Answer 44

1. smooth 2. one 3. endomysium 4. sarcomeres 5. interdigitating 6. sarcoplasm

Question 45

* In the walls of hollow \_\_₁, the fibers are grouped into \_\_₂ of smooth muscle tissue. * Often \_\_₃ sheets are present, with their fibers oriented at ___ \_\_\_₄ to each other. * ***Longitudinal layer***: the muscle fibers run \_\_₅ to the long axis of the organ. * ***Circular layer***: the muscle fibers run \_\_₆ the \_\__​7 of the organ.

Answer 45

1. viscera 2. sheets 3. two 4. right angles 5. parallel 6. around 7. circumference

Question 46

* The ***circular layer \_\_***₁ the hollow organ, and the longitudinal layer \_\_₂ the organ's \_\_₃ * These muscle layers \_\_ ₄ alternate waves of \_\_ ₅ and relaxation that \_\_₆ substances through the organ... a process called \_\_ ₇ ("around contraction")

Answer 46

1. constricts 2. shortens 3. length 4. generate 5. contraction 6. propel 7. peristalsis