Chapter 10 - Muscle Tissue

Question 1

Muscle tissue

Answer 1

• main function is contraction - contains specialized contractile proteins
• 2 types of myofilaments
• elongated shape of cells
• multinucleated

Question 2

What are the specialized strucutres in muscle tissue?

Answer 2

• sarcoplasm
• sarcolemma
• sarcoplasmic reticulum
• sarcomeres

Question 3

Skeletal muscle tissue

Answer 3

• rapid, strong contractions
• voluntary
• nuclei tend to be at periphery
• striated
• limited regeneration

Question 4

Cardiac muscle tissue

Answer 4

• strong contractions, fast or slow
• involuntary
• specialized structure for communication called intercalated disks
• uninucleated, nucleus is centered
• striated
• very poor regeneration

Question 5

Smooth muscle tissue

Answer 5

• slow contractions
• involuntary
• elongated, tapered to a point at each end
• good regeneration involving mitosis

Question 6

What is the organization of muscle tissue?

Answer 6

• muscles are covered in epimysium
• fascicle is covered in perimysium
• myofibers are covered in endomysium
• myofibers make up myofibrils
• sarcomeres make up myofibers
• myofilaments make up sarcomeres

Question 7

What are the histological characteristics of muscle tissue?

Answer 7

• striations
• multinucleated myofibers
• nuclei at periphery
• vascularized
• each myofiber is innervated

Question 8

Sarcomeres

Answer 8

• microscopic unit of contraction
• highly organized array of myofilaments
• striated (light band is I band, dark band is A band)
• converts chemical energy to mechanical energy
• filaments slide along one another during contraction

Question 9

What proteins do sarcomeres contain?

Answer 9

• actin
• myosin
• tropomyosin
• troponin

Question 10

Explain the contractile protein arrays of sarcomeres

Answer 10

• thick filaments; made of myosin
• thin filaments; made of actin, tropomyosin and troponin

Question 11

What proteins in the sarcomere have to interact in order for contraction to occur?

Answer 11

• calcium binds to troponin, making tropomyosin move, revealing binding sites for myosin on actin
• myosin swivels and grabs onto actin and pulls the thin filament towards the center of sarcomere, bringing Z discs closer together

Question 12

What are the steps of skeletal muscle contraction?

Answer 12

1. ATP binding activates myosin head
2. Ca2+ released from SR, binds to troponin
3. conformational change in troponin occurs; moves tropomyosin so that binding sites on actin are exposed
4. myosin binds to actin, ATP hydrolysis occurs -> movement of myosin head
5. pulls thin filaments toward center of sarcomere, sarcomere shortens
6. length of myofilaments does not change
7. myosin binds another ATP and detaches from actin