Muscle Structure and Organization

Question 1

What are the different types of muscle?

Answer 1

Skeletal, cardiac, and smooth

Question 2

Muscle is a ____________ tissue.

Answer 2

Heterogeneous

Question 3

What is the composition (and %) of skeletal muscle?

Answer 3

• Water (75%)
• Protein (≈18%)
• Fat (3%)
• Carbohydrate (1%)
• Ash (1%)

Question 4

As fat increases, the _______ will decrease in the composition of skeletal muscle.

Answer 4

Water

Question 5

Give me the term:
? = connective tissue surrounding the muscle bundle (dense irregular)

Answer 5

Perimysium

Question 6

Give me the term:
? = connective tissue connecting muscle to bone

Answer 6

Tendon

Question 7

Give me the term:
? = connective tissue surrounding the entire muscle

Answer 7

Epimysium

Question 8

Give me the term:
? = connective tissue surrounding a fiber

Answer 8

Endomysium

Question 9

What does the muscle fiber contain?

Answer 9

Myocyte, muscle cell, and myofiber.

Question 10

In the muscle cell, the sarcolemma is considered the…

Answer 10

muscle plasma membrane

Question 11

In the muscle cell, the sarcoplasm is considered the…

Answer 11

cytoplasm

Question 12

In the muscle cell, the mitochondria is considered the…

Answer 12

organelle of the muscle cell (powerhouse)

Question 13

In the muscle cell, the myofilaments contain…

Answer 13

• thick filaments (myosin)
• thin filaments (actin) (also known as the motor protein)

Question 14

In the muscle cell, the sarcoplasmic reticulum is considered the…

Answer 14

calcium reservoir - restores calcium to control muscle contraction.

Question 15

What is the smallest contractile unit of muscle?

Answer 15

Sarcomere

Question 16

Actin and myosin are _______ proteins.

Answer 16

Contractile

Question 17

What is in a myosin filament?

Answer 17

• Myosin heavy chains (MHc).
  ^There are two MHcs per myosin molecule.

Question 18

What is in an actin filament?

Answer 18

G-actin (Globular actin) and F-actin (filamentous actin)

Question 19

In the thin filament, what kind of regulatory proteins are there?

Answer 19

• Tropomyosin
• Troponin complex:
  - TnT
  - TnC
  - TnI

Question 20

_______ is a barrier between actin and myosin protein filaments and prevents __________________.

Answer 20

Tropomyosin, prevents irregular contracting

Question 21

What are the three subunits of the troponin complex?

Answer 21

1) TnT
2) TnC
3) TnI

Question 22

What does TnT bind to?

Answer 22

Binds to tropomyosin and anchors

Question 23

What does TnC bind?

Answer 23

Binds intracellular calcium

Question 24

What does TnI bind?

Answer 24

Binds actin and inhibits (prevents) actin-myosin interaction

Question 25

_______ promotes muscle contraction, whereas _________ blocks muscle contraction.

Answer 25

Troponin, tropomyosin

Question 26

In the sarcomere, the ____ band is the dark region and is _________.

Answer 26

A-band, anisotropic

Question 27

In the sarcomere, the ____ band is the light region and is _________.

Answer 27

I-band, isotropic

Question 28

What does titin help with?

Answer 28

Helps keep the structural organization within a myofibril aligned and rests tension

Question 29

When a muscle is fully contracted, there is a ______ gap between the Z lines and a ___________ in the H zone.

Answer 29

Shorter, reduction

Question 30

What helps keep the Z-lines aligned?

Answer 30

Desmin and intermediate filaments

Question 31

What links the myofibrils and cytoskeleton to the extracellular matrix through the sarcolemma?

Answer 31

Costameres

Question 32

Costameres are ________-associated _________ complex

Answer 32

dystrophin, glycoprotein

Question 33

What is Duchenne muscular dystrophy?

Answer 33

- It is the complete loss of dystrophin - There is a loss of mechanical stability of the sarcolemma.