CSCS Anatomy and Physiology

Question 1

Name the connective tissues of the muscle from the muscle cell to the whole muscle

Answer 1

1. Endomysium (surrounds individual muscle cell)
2. Perimysium (surrounds the fasciculus-group of muscle cells)
3. Epimysium (surrounds the entire muscle)

Question 2

What is the name of the fluid that is contained within a muscle cell?

Answer 2

Sarcoplasm

Question 3

Muscle cells are made up of hundreds of _____(1)_____, which are made up of contractile proteins known as _____(2)_____, of which there are two known as _____(3a)_____ and _____(3b)_____.

Answer 3

1. Myofibrils
2. Myofilaments
   3a. Actin
   3b. Myosin

Question 4

Which myofilament contains troponin and tropomyosin?

Answer 4

Actin

Question 5

What is the functional unit of the muscle cell?

Answer 5

Sarcomere (this is also known as the contractile unit of the muscle cell)

Question 6

The thin filaments are anchored to which part of the sarcomere?

Answer 6

Z lines

Thin filament is another name for actin

Question 7

Where in the sarcomere is myosin anchored to?

Answer 7

Myosin (also known as the thick filament) is anchored at the M bridge (which is the center of the H zone)

Question 8

What area of the sarcomere ONLY contains actin filaments?

Answer 8

I - band

Question 9

The H - zone corresponds with the presence of only which myofilament within a sarcomere?

Answer 9

Myosin

Question 10

Which are of the sarcomere is associated with the length of the myosin filaments?

Answer 10

A - band

Question 11

Each actin filament is surrounded by _____(1)_____ myosin filaments, which itself is surrounded by ______(2)_____ actin filaments.

Answer 11

1. Three

2. Six

Question 12

A sarcomere is the distance between two __________.

Answer 12

Z - lines

Question 13

What is the definition of a motor unit?

Answer 13

A motor neuron (nerve) and all of the muscle fibers that it innervates.

Question 14

How many motor nerves can a muscle be innervated by?

Answer 14

Only one. A motor nerve can innervate over a thousand muscle fibers but a fiber will only ever be innervated by one motor neuron.

Question 15

Name the membrane of the muscle cell.

Answer 15

Sarcolemma

Question 16

How does movement occur?

Answer 16

Force is generated in muscles by actin and myosin pulling on each other, force is transferred through levels of connective tissue to tendon, tendon pulls bone to move

Question 17

What are the aspects of the myosin heads that allows for muscle contraction to occur?

Answer 17

1. Myosin head binds to actin allowing the myofilaments to pull across each other
2. Binds to ATP, making the energy molecule available for muscle contraction
3. Contains myosin ATP-ase, which hydrolyzes (breaks down) ATP, allowing for the use of the energy molecule for muscle contraction

Question 18

Which protein on actin covers the binding site of the myosin head?

Answer 18

Tropomyosin, which is responsible for the inhibition of the actin-myosin binding site

Question 19

Which protein is responsible for pulling tropomyosin off the binding site on actin?

Answer 19

Troponin

Question 20

Name the five steps involved in the sliding filament theory

Answer 20

Step 1: Resting phase
Step 2: Excitation-Contraction Coupling phase
Step 3: Contraction phase
Step 4: Recharge phase
Step 5: Relaxation phase

Question 21

During which stage of the sliding filament theory is calcium stored in the sarcoplasmic reticulum?

Answer 21

Resting phase. During this phase there is little tension in the muscle due to very few myosin cross-bridges bound to actin

Question 22

During the excitation-coupling phase, what actions occur to allow myosin to bind to actin

Answer 22

Calcium is released from the sarcoplasmic reticulum into the sarcoplasm and binds to troponin. Troponin shifts its position, pulling tropomyosin away from the actin active site and exposing it. The ATPase portion of the myosin head hydrolyzes ATP, thereby making energy available.

Question 23

What two actions occur during the contraction stage of the sliding filament theory?

Answer 23

1. The head of the myosin tilts (powerstroke) and pulls on the actin molecule.
2. A new ATP binds to the emptied ATP binding site on the myosin head, causing the release of the actin-myosin bond.

Question 24

What is the name of the stage of the sliding filament theory that is simply a repetition of the previous two stages?

Answer 24

Recharge stage

Question 25

What three items within the muscle must be continually available for measurable shortening of said muscle to occur?

Answer 25

1. Calcium
2. ATP
3. ATPase

Question 26

What causes the muscle to move from the recharge phase to the relaxation phase?

Answer 26

The muscle is no longer activated via the motor neuron

Question 27

What four actions occur during the relaxation stage of the sliding filament theory of muscle contraction?

Answer 27

1. Calcium is released from its binding site on troponin and taken back up into the sarcoplasmic reticulum.
2. Myosin is released from actin when the new ATP binds to the myosin head.
3. Troponin shifts back to resting position.
4. Tropomyosin shifts back to resting position, covering the active sites on actin.

Question 28

What is the underlying determinant of how much force a muscle can produce?

Answer 28

The number of actin-myosin bonds

Question 29

Which type of muscle contraction involves the Z-lines moving toward the center of the sarcomere?

Answer 29

Concentric contraction. This is a shortening of the muscle. During this type of contraction the H-zone and I-bands will shrink in length

Question 30

What type of muscle contraction occurs when the I-bands increase in length?

Answer 30

Eccentric contraction. This involves the muscle lengthening. The H-zone will also increase in length during this type of muscle contraction

Question 31

What is the definition of an isometric muscle action?

Answer 31

A contraction that involves myosin-actin binding, but no movement occurs. The sarcomere, I-bands and H-zone all remain unchanged in length.

Question 32

During which type of muscle action does the external resistance exceed the internal force of the muscle?

Answer 32

An eccentric contraction. For a concentric contraction to occur, the muscle force must exceed the external resistance. During an isometric contraction, the muscle force and external resistance will be equal.

Question 33

During what type of muscle action does the A-band remain the same length?

Answer 33

Any muscle action. The A-band is the area in which the myosin filament resides. As the length of the myosin filament never changes during any type of contraction, the A-band length will never change. Sorry, this is a trick question.

Question 34

Define the two anatomical parts of the nervous system and how they are involved in movement.

Answer 34

The nervous system is divided into the central nervous system (brain and spinal cord) and peripheral nervous system (motor and sensory peripheral nerves). The CNS processes information coming from different regions of the body or from the external environment and sends out motor signals in response to the stimuli. The peripheral nervous system transmits these motor signals from the CNS to the muscles and sensory information from the body to the CNS.

Question 35

Define the all-or-none principle

Answer 35

If a motor neuron fires, it activates all of the muscle fibers in the motor unit or none at all

Question 36

Neurally, how does muscle action occur from the central nervous system to the muscle itself?

Answer 36

The central nervous system creates an action potential in the motor neuron, which then moves down the motor nerve to the neuromuscular junction. This action potential continues along the sarcolemma and into the sarcoplasmic reticulum through the transverse tubules, causing the release of calcium.

Question 37

What neurotransmitter transfer the action potential across the neuromuscular junction?

Answer 37

Acetylcholine