Chapter 8 Muscle Tissue

Question 1

What are the 5 properties of muscles?

Answer 1

• Excitability - respond to chemicals released from motor neurons
• Conductivity - ability to propagate electrical signals over membrane
• Contractility - ability to shorten and generate force
• Extensibility - ability to be stretched without damaging the tissue
• Elasticity - ability to return to original shape after being stretched

Question 2

Which of the following characteristics do neurons and muscle cells share?

A. Extensibility
B. Excitability
C. Contractility
D. Elasticity

Answer 2

B. Excitability

Question 3

What are the three types of muscles?

Answer 3

• Skeletal -Voluntary, Striated, Multinucleate, Attached to bone, skin, or fascia

Cardiac - Involuntary, Striated, Mononucleate, Autorhythmic (can self regulate beat)

Smooth - Involuntary, Non-striated, Mononucleate, Hair follicles, walls of hollow organs

Question 4

Skeletal Muscle Terminology

What is a muscle?

Answer 4

A group of fasicles

Question 5

Skeletal Muscle Terminology

What are fasicles?

Answer 5

A group of muscle of cells(fibers)

Question 6

Skeletal Muscle Terminology

What are muscle cells?

Answer 6

Long bundles of protiens (myofibrils)

Question 7

Skeletal Muscle Terminology

What are myrofibrils?

Answer 7

Organized into sacomeres (contractile unit of muscles)

Question 8

What are sarcolemma and sarcoplasm?

Answer 8

Sarcolemma - muscle cell membrane

Sarcoplasm - cytoplasm of a muscle cell

Question 9

What is inside the sarcoplasm?

Answer 9

Myofibrils - long bundles of proteins
Myoglobin - stores oxygen for use
Glycogen - A polymer of sugar

Question 10

What are tube-like structures which penetrate the interior of the cell of the sarcolemma?

Answer 10

Transverse tubules (T-tubules) - filled with extracellular fluid

Question 11

What is the Sarcoplasmic reticulum?

Answer 11

• muscle cell ER
  
  • Terminal cisternae - sacs of the SR, closely associate with T-Tubules
  • Storage area for calcium ions IN the muscle cell.

Question 12

What are the three types of myofilaments(protiens) and what do they form?

Answer 12

• Thick filaments  myosin protein
• Thin filaments  actin protein
• Elastic filaments  titin protein
• Together they form the sarcomere or the contractile unit

Question 13

What are the functions/structures of the Thick filaments of myofilaments?

Answer 13

• Many myosin protein
• A single myosin is shaped like a golf club (head is mobile), two twist together to make dimer (dimer = two units)
• A thick filament consists of hundreds of myosin dimers
• Binds and hydrolyzes ATP

Question 14

What are the functions/structures of the Thin filaments of myofilaments?

Answer 14

• Two chains of actin proteins, tropomyosin and troponin
• Each actin unit (red ball) has an active site that can bind to the head of a myosin protein
• Tropomyosin (white stripe) blocks the active site of myosin in relaxed muscles
• Troponin (yellow) binds tropomyosin. In the presence of calcium, troponin moves tropomyosin off active sites of actin

Question 15

Which of the following molecules is the largest?

A. Myofilament
B. Myofibril
C. Myosin
D. Troponin

Answer 15

B. Myofibril

Question 16

What and where is the A band, I Band, Z disc and M line in the picture?

Answer 16

• A band = Thick filament
  
  • Dark in color
  • Partially overlaps with thin filaments
  • Lighter in color at H Band, which is thick filament only
• I band = Thin filament only
  
  • Light in color

Z disc = edge of sarcomeres
M line = mid of sarcomere
Both contain accessory proteins for stabilization
Pattern of dark and light are the striations

Question 17

JUST REVIEW

Answer 17

JUST REVIEW

Question 18

What is Sarcomere Contration

Answer 18

• Sliding filament theory
• During contraction, thin filaments are pulled along thick filaments toward M-line (middle) of the sarcomere
  
  • H band (zone) decreases in size
  • I band decreases in size
• USES ATP!!
• Contraction of all sarcomeres, in all myofibrils, in all cells causes the muscle to contract as a whole