Muscle

Question 1

what are the three types of muscle?

Answer 1

Smooth, Skeletal and Cardiac

Question 2

Give 3 examples of where smooth muscle would be found.

Answer 2

Blood vessels, airways, GI tract, vas deferens, bladder, uterus.

Question 3

Is skeletal muscle multinucleate or mononucleate?

Answer 3

Multinucleate

Question 4

Is smooth muscle multi or mononucleate?

Answer 4

mononucleate

Question 5

what attaches muscles to bone?

Answer 5

Tendons

Question 6

what replaces muscle cells after injury?

Answer 6

satellite cells and hypertrophy of other cells to compensate

Question 7

what do the “thick” and “thin” filaments of muscle fibers correspond to?

Answer 7

thick - myosin filament

thin - actin filament

Question 8

what is a sarcomere?

Answer 8

the basic unit of striated muscle tissue

Question 9

what is a cross bridge?

Answer 9

the part of the myosin filament that binds to actin, it contains both actin and ATP binding sites.

Question 10

describe the cross bridge cycle.

Answer 10

the process by which cross bridges on the myosin filament bind to the actin filaments, which induces contraction. the cycle ends with the cross bridges detaching and the muscle returning to a relaxed state

Question 11

what covers the myosin binding site on the actin filaments?

Answer 11

tropomyosin

Question 12

what causes the myosin binding sites on the actin to be exposed?

Answer 12

binding of calcium to troponin; troponin alters shape and pulls the tropomyosin away, leaving the binding site exposed.

Question 13

what is excitation-contraction coupling?

Answer 13

conversion of an electrical signal to mechanical force in a muscle cell

Question 14

what do transverse tubules do?

Answer 14

responsible for spreading depolarization throughout the entire muscle cell

Question 15

how is calcium released from the sarcoplasmic reticulum?

Answer 15

DHP receptors detect depolarization in the transverse tubule, they then send a message to ryanodine receptors, which causes Calcium channels in the sarcoplasmic reticulum to open and release calcium.

Question 16

what is a motor unit?

Answer 16

motor neurons + muscle fibres

Question 17

what is the name given to the force exerted by muscle?

Answer 17

tension

Question 18

what is the name given to the force being exerted on muscle?

Answer 18

load

Question 19

what is the name given to contraction with constant length

Answer 19

isometric

Question 20

what is the name given to contraction with shortening length?

Answer 20

isotonic

Question 21

what is the name given to contraction with increasing length?

Answer 21

lenghthening

Question 22

in a muscle twitch, what name is given to the time between an AP being generated and the muscle displaying a response?

Answer 22

latent period

Question 23

what happens to muscle as load increases?

Answer 23

contraction velocity and distance shortened decreases.

Question 24

what is tetanus?

Answer 24

sustained contraction of muscle fibres with reduced/no relaxation

Question 25

why do muscles fail to contract during tetanus?

Answer 25

calcium levels are never low enough to allow tropomyosin to reblock binding sites on actin

Question 26

what are the antagonistic pairs of muscle arranged around a limb referred to as?

Answer 26

flexors and extensors

Question 27

what causes myosin heads to detach from actin filaments?

Answer 27

binding of ATP to myosin

Question 28

how does calcium transfer back into the sarcoplasmic reticulum?

Answer 28

via calcium ATPase (which is powered by ATP). this ends contraction

Question 29

what is the purpose of fatigue?

Answer 29

to prevent muscles using up vast amounts of ATP which would cause rigor.

Question 30

when does fatigue occur?

Answer 30

after repeated muscle stimulation.

Question 31

What 3 types of skeletal muscle fibre are there?

Answer 31

Slow and fast oxidative fibres and fast glycolytic fibres

Question 32

what characterises the two types of skeletal muscle fibre?

Answer 32

In fast fibres, myosin has high ATPase activity, in slow fibres myosin has low ATPase activity

Question 33

How much do the 3 types of muscle fibre resist fatigue?

Answer 33

Slow oxidative - resist fatigue strongly Fast oxidative - intermediate resistance Fast glycolytic - fatigue quickly

Question 34

what is an increase in the number of active motor units referred to as?

Answer 34

recruitment

Question 35

what innervates smooth muscle tissue?

Answer 35

autonomic nervous system

Question 36

how are the filaments arranged in smooth muscle

Answer 36

diagonally

Question 37

what does calcium bind to in smooth muscle during cross bridge activation?

Answer 37

calmodulin

Question 38

what does calmodulin bind to in smooth muscle during cross bridge activation

Answer 38

myosin light chain kinase

Question 39

what does myosin light chain kinase do?

Answer 39

phosphorylates cross bridges in smooth muscle, which in turn allows them to bind to actin filaments.

Question 40

How does smooth muscle relax

Answer 40

action of myosin light chain phosphatase dephosphorylates cross bridges.

Question 41

skeletal muscle has a baseline calcium level: true or false?

Answer 41

False

Question 42

smooth muscle has a baseline calcium level: true or false?

Answer 42

true

Question 43

what is the purpose of having a baseline calcium level in some muscle cells?

Answer 43

maintain a constant level of tension

Question 44

what types of smooth muscle are there?

Answer 44

single unit and multiunit types; most smooth muscle in organs are a mixture of both types