A&P Test 2 Muscles only

Question 1

What is the plasma membrane of a muscle cell?

Answer 1

Sarcolemma

Question 2

What are 3 characteristics of skeletal muscle?

Answer 2

It is striated, voluntary and multi-nuclear.

Question 3

What do T (transverse) tubules do?

Answer 3

They store Calcium and deliver it for muscle contraction.

They transmit action potential in the cell, an electric signal that allows entire muscle to contract simultaneously

Question 4

What are the thin and thick filaments in muscle?

Answer 4

Thin - actin. Thick - myosin.

Question 5

What is the contraction unit of a muscle fiber?

Answer 5

Sacomere

Question 6

What is the cytoplasm of the muscle fiber?

Answer 6

Sarcoplasm

Question 7

What are myofibrils?

Answer 7

Cylindrical structures that are responsible for muscle fiber contraction.

Question 8

What do myofibrils consist of?

Answer 8

Thin filaments (actin), thick filaments (myosin) and titin.

Question 9

What is the network around individual myofilaments?

Answer 9

sarcoplasmic reticulum (SR)

Question 10

What are sarcomeres?

Answer 10

Myofilaments organized into repeating functional units

Question 11

What is the smallest contractile unit of a striated muscle cell (fiber)?

Answer 11

Sarcomere

Question 12

where would the greatest concentration of calcium ions be in resting skeletal muscle?

Answer 12

In the sarcoplasmic reticulum, in the cisternae

Question 13

Each sarcomere has dark bands and light bands. What are they?

Answer 13

Dark bands are A bands, containing myosin. Light bands are I bands, containing actin.

Question 14

How many proteins does a typical thin filament have?

Answer 14

4: G-actin, nebulin, tropomyosin and troponin

Question 15

What are the 4 proteins of a thin filament?

Answer 15

G-actin, nebulin, tropomyosin, troponin

Question 16

What are the 5 steps of the contraction cycle?

Answer 16

First, a neuron signal releases Ca from SR

1. Exposure of active sites (F actin becomes exposed & interacts w/ myosin)
2. Formation of cross-bridges
3. Pivoting of myosin heads
4. Detachment of cross-bridges
5. Reactivation of myosin

Question 17

Calcium ions are released in what process?

Answer 17

Contraction

Question 18

In contraction, what is released?

Answer 18

Calcium ions

Question 19

What important function does the SR play in muscle contraction?

Answer 19

It transmits action potential to myofibrils

Question 20

What is the active site in a muscle contraction?

Answer 20

F-actin is the active site

Question 21

What blocks the active site in a resting stage?

Answer 21

Tropomin & tropomysin

Question 22

What binds actin and myosin?

Answer 22

Calcium

Question 23

What muscle proteins are directly involved in muscle contraction?

Answer 23

Myosin and actin

Question 24

What are the 2 parts of myosin?

Answer 24

Head and tail

Question 25

What is the sliding filament theory?

Answer 25

``` Skeletal Muscle Contraction Sliding filament theory Thin filaments of sarcomere slide toward M line, alongside thick filaments The width of A zone stays the same Z lines move closer together ```

Question 26

The thin filaments in a sarcomere...

Answer 26

...extend from the Z lines.

Question 27

Filament, fiber, fibril: arrange from largest to smallest

Answer 27

Fiber, fibril, filament

Question 28

What is the order of energy provided to a muscle cell: glucose, creatine phosphate, ATP

Answer 28

ATP, creatine phosphate, glucose

Question 29

What is the Z line?

Answer 29

Z lines mark the boundary between adjacent sarcomeres.