Chapter 6 Pt. 2

Question 1

A muscle contracts when the _____ ________ slide along the myosin filaments, increasing the degree of overlap between actin and myosin and thus shortening the sarcomere

Answer 1

actin filaments

Question 2

A muscle contracts when the actin filaments slide along the ________ _________, increasing the degree of overlap between actin and myosin and thus shortening the sarcomere

Answer 2

myosin filaments

Question 3

A muscle contracts when the actin filaments slide along the myosin filaments, increasing the degree of overlap between _____ and ______ and thus shortening the sarcomere

Answer 3

actin

myosin

Question 4

A muscle contracts when the actin filaments slide along the myosin filaments, increasing the degree of overlap between actin and myosin and thus shortening the __________

Answer 4

sarcomere

Question 5

When many __________ shorten, the muscle as a whole contracts

Answer 5

sarcomeres

Question 6

When many sarcomeres shorten, the muscle as a whole ________

Answer 6

contracts

Question 7

The club-shaped _______ ______ are the key to the movement of actin filaments and, therefore, to muscle contraction

Answer 7

myosin heads

Question 8

What are the steps of the sliding filament model?
1) 
2) 
3) 
4)  
5)

Answer 8

1) resting sarcomere
2) Cross-bridge attachment
3) Bending of myosin head (the power stroke)
4) Cross-bridge detachment
5) Myosin reactivation

Question 9

At the start of each cycle, the myosin heads have already split a molecule of ATP to _____ and _________ _________ (___)

Answer 9

ADP
inorganic phosphate
(Pi)

Question 10

What happens during Cross-bridge attachment?

Answer 10

myosin head binds to an actin filament and acts as a bridge between the thick and thin filaments

Question 11

What happens during the Bending of myosin head (the power stroke) ?

Answer 11

the ADP and inorganic phosphate are released from the myosin head

Question 12

What happens during the Cross-bridge detachment?

Answer 12

the new ATP molecules now bind to the myosin heads, causing the myosin heads to disengage form the actin

Question 13

What happens during the Myosin reactivation?

Answer 13

the myosin heads split the ATP into ADP and Pi and store the energy, causing the contraction cycle to begin again

Question 14

Muscle cells contain the proteins ________ and _________, which together form a troponin-tropomyosin complex

Answer 14

troponin

troponyosin

Question 15

Muscle cells contain the proteins troponin and troponyosin, which together form a _______-_________ _______

Answer 15

troponin-tropomyosin complex

Question 16

What is sarcoplasmic reticulum?

Answer 16

an elaborate form of smooth endoplasmic reticulum found in muscle cells

Question 17

________ ions are stored inside sarcoplasmic reticulum

Answer 17

Calcium

Question 18

What are transverse tubules (T tubules)?

Answer 18

tiny, cylindrical pockets in the muscle cells plasma membrane

Question 19

transverse tubules (T tubules) carry signals from motor neurons deep into the muscle cell to virtually every _________

Answer 19

sarcomere

Question 20

What is Rigor Mortis?

Answer 20

when muscles become stuff within a few hours after death

Question 21

Why do muscles become stuff within a few hours after death?

Answer 21

calcium ions begin to leak out of the sarcoplasmic reticulum, initiating muscles contract

Question 22

The muscles relax after __ to __ days after death

Answer 22

2 to 3

Question 23

What is neuromuscular junction?

Answer 23

the junction between the tip of a motor neuron and a skeletal muscle cell

Question 24

A muscle contraction is the result of these key steps:

1)
2) acetylcholine is released at the neuromuscular junction
3) when acetylcholine binds to receptors on the plasma membrane of the muscle cell, an electrochemical message is generated
4) the electrochemical message spreads through T tubules, causing the release of calcium ions form the sarcoplasmic reticulum

Answer 24

1) a nerve impulse reaches the neuromuscular junction

Question 25

A muscle contraction is the result of these key steps: 1) a nerve impulse reaches the neuromuscular junction 2) 3) when acetylcholine binds to receptors on the plasma membrane of the muscle cell, an electrochemical message is generated 4) the electrochemical message spreads through T tubules, causing the release of calcium ions form the sarcoplasmic reticulum

Answer 25

2) acetylcholine is released at the neuromuscular junction

Question 26

A muscle contraction is the result of these key steps: 1) a nerve impulse reaches the neuromuscular junction 2) acetylcholine is released at the neuromuscular junction 3) 4) the electrochemical message spreads through T tubules, causing the release of calcium ions form the sarcoplasmic reticulum

Answer 26

3) when acetylcholine binds to receptors on the plasma membrane of the muscle cell, an electrochemical message is generated

Question 27

A muscle contraction is the result of these key steps: 1) a nerve impulse reaches the neuromuscular junction 2) acetylcholine is released at the neuromuscular junction 3) when acetylcholine binds to receptors on the plasma membrane of the muscle cell, an electrochemical message is generated 4)

Answer 27

4) the electrochemical message spreads through T tubules, causing the release of calcium ions form the sarcoplasmic reticulum

Question 28

The contraction of ______ muscles then stretches the sarcomere back to its original length

Answer 28

other

Question 29

What are muscle cramps(or spasms)?

Answer 29

forceful, involuntary muscle contraction

Question 30

What are the possible causes of muscle cramps?

Answer 30

calcium, magnesium, or potassium

Question 31

What happens if too many calcium ions enter the cell?

Answer 31

those ions can destroy proteins within the cell, causing it to die

Question 32

What is muscular dystrophy?

Answer 32

a general term for a group of inherited conditions

Question 33

What is Ducheme Muscular Dystrophy?

Answer 33

caused by a defective gene for production of the protein dystrophin

Question 34

What is one of the most common forms of muscular dystrophy?

Answer 34

Ducheme Muscular Dystrophy

Question 35

Ducheme Muscular Dystrophy: | dead muscle cells are replaced by ____ and _________ _______, so the skeletal muscles become progressively ________

Answer 35

fat connective tissue weaker

Question 36

What are the 2 important ways to vary the contraction of whole muscles?

Answer 36

1) changing the number of muscle cells contracting at a given moment 2) changing the force of contraction in individual muscle cells by altering the frequency of stimulation

Question 37

What is motor unit?

Answer 37

a motor neuron and all the muscle cells it stimulates

Question 38

What is recruitment?

Answer 38

the process by which the nervous system increases the strength of a muscle contraction by increasing the number of motor units being stimulated

Question 39

True or False: When a muscle is relaxed, all of its motor units are relaxed

Answer 39

False; Even when a muscle is relaxed, some of its motor units are active

Question 40

What is the result of, "a muscle is relaxed, some of its motor units are active"?

Answer 40

the muscle is usually firm and solid, even when it’s not being used