Muscle cell structure.

Question 1

Skeletal muscle tissue [long cylindrical]:

Answer 1

Located in voluntary muscle.

They are multi-nucleated.

They are striated.

The release of acetylcholine induces an action potential.

Question 2

Contractions of skeletal muscle tissues are dependent on:

Answer 2

Stimulation by somatic motor neurons, which form a chemical synapse called the neuromuscular junction.

Question 3

One motor end plate per:

Answer 3

Muscle fiber.

Question 4

Cardiac muscle tissue [long irregularly shaped cells]:

Answer 4

Striated & found in the heart.

Uni-nucleated.

Connected by gap junctions.

Question 5

Autorhythmicity:

Answer 5

Action potential arises within the muscle tissue.

You don’t need nervous stimulation for contractions in cardiac tissue.

Question 6

Intercalated disks:

Answer 6

Where gap junctions are located.

The intercalated disks are located between cells.

Question 7

Action potential in skeletal muscle cells are:

Answer 7

Transmitted from cell to cell via electrical synapses.

Question 8

Skeletal muscle cells are called:

Answer 8

Muscle fibers.

Question 9

Smooth muscle tissue [spindle shaped]:

Answer 9

Located in the viscera, involved in the reflex response.

Smaller than muscle fiber.

Contains a single nucleus.

Question 10

types of smooth muscle tissue:

Answer 10

Single unit.

Multi-unit.

Question 11

Single unit (smooth muscle tissue):

Answer 11

The cells are connected by electrical synapses.

They also have autorhythmicity.

Ex: GI Tract, uterus.

Question 12

Multi-unit (smooth muscle tissue):

Answer 12

They have no electrical synapses.

They respond to neurotransmitters or hormones.

They do not produce an action potential.

Question 13

What does smooth multi-unit muscle tissue produce:

Answer 13

Depolarizing postsynaptic potential that stimulates contraction.

Question 14

Sarcolemma:

Answer 14

Plasma-membrane of the skeletal muscle.

Question 15

Sarcoplasm:

Answer 15

Cytosol [ICF].

Question 16

Myofibril:

Answer 16

Cylindrical structures that extends the length of the muscle fiber and contain sarcomeres.

Contraction of sarcomeres causes contraction of the muscle fiber.

Myofibril can also contract.

Question 17

Sarcoplasmic reticulum:

Answer 17

Calcium ion storage organ.

Question 18

Transverse tubules:

Answer 18

Propagate action potentials from the sarcolemma to the interior of the muscle fiber.

Question 19

Myofilament arrangement produces:

Answer 19

A & I bands.

Question 20

Types of filaments:

Answer 20

Thick filament.

Thin Filament.

Question 21

Thick filaments are attached to:

Answer 21

The M line.

Question 22

___ thin filaments surrounds ____ thin filament.

Answer 22

6 thin surrounds 1 think.

Question 23

Z-Disk:

Answer 23

Protein that holds the thin filament in place.

Located at the center of each I band.

Question 24

Sarcomere:

Answer 24

Contractile unit of a myofibril.

Each sarcomere contracts.

It is the area between two adjacent z-disks.

Question 25

Titin:

Answer 25

Gives elasticity to the myofibrils.

Question 26

Nebulin:

Answer 26

Assemble & stabilizes the thin filaments.

Question 27

Thin filaments are made up of:

Answer 27

G-actin. Tropomyosin. Troponin.

Question 28

G-actin:

Answer 28

Each G-actin contains 1 myosin-binding site. Globular protein that can polymerize to form a long chain.

Question 29

Myosin binding site:

Answer 29

Where thick filaments meets the thin filaments.

Question 30

In a thin filament, two:

Answer 30

Two G-actin are coiled together to form an F-actin.

Question 31

Tropomyosin:

Answer 31

A filamentous protein that lies along F-actin, and which has the ability to block myosin-binding sites.

Question 32

At rest, Tropomyosin lies:

Answer 32

Over the myosin binding site.

Question 33

Troponin:

Answer 33

A protein that consists of three subunits. Troponin T. Troponin I. Troponin C.

Question 34

What subunits of troponin interacts with tropomyosin:

Answer 34

Troponin T & I.

Question 35

Troponin T:

Answer 35

Holds tropomyosin in place.

Question 36

Troponin I:

Answer 36

Ensures myosin remains over the myosin binding site.

Question 37

Troponin C:

Answer 37

Can bind to calcium ions and regulates the activity of troponin I & T. In the presence of ca, it moves tropomyosin away from myosin binding site.

Question 38

Thick filaments:

Answer 38

Made primarily of the protein myosin.

Question 39

Myosin:

Answer 39

Made up of six subunits. 2 heavy chains & 4 light chains.

Question 40

In the presence of calcium ions, troponin C:

Answer 40

Moves tropomyosin away from myosin binding site.

Question 41

Heavy chain of myosin:

Answer 41

The 2 head & tail.

Question 42

The light chain of myosin:

Answer 42

Flexible hinge region.

Question 43

Each myosin head has:

Answer 43

One G-actin binding site. One ATPase site.

Question 44

The head of the myosin is also called:

Answer 44

Cross-bridges.

Question 45

One thick filament consists of:

Answer 45

200-400 myosin molecules.

Question 46

The middle of the thick filament lacks:

Answer 46

cross-bridges.

Question 47

Barezone:

Answer 47

The middle of the thick filament that lacks cross-bridges. Barezones are attached to the M-line in the sarcomere.