Chapter 11: Musculoskeletal System

Question 1

3 main types of muscle

Answer 1

skeletal muscle, smooth muscle, cardiac muscle

Question 2

skeletal muscle

Answer 2

voluntary muscle control

invovled in support and movement, propulsion of blood, and thermoregulation

Question 3

which muscles are striated

Answer 3

skeletal

cardiac

Question 4

which muscles are NOT striated

Answer 4

smooth muscle

Question 5

which muscles are multi-nucleated

Answer 5

skeletal

Question 6

which muscles are uni-nucleated

Answer 6

smooth

cardiac

Question 7

involuntary muscle types

Answer 7

cardiac muscle

smooth muscle

Question 8

basic contractile unit of skeletal muscle

Answer 8

sarcomere

Question 9

sarcomere

Answer 9

basic contractile unit of skeletal muscle

Question 10

sarcomeres are made up of…

Answer 10

thick (myosin) filaments
thin (actin) filaments

Question 11

what regulates the actin-myosin interactions?

Answer 11

tyoponin and tropomyosin

Question 12

muscle contraction steps

Answer 12

1) atp binds to myosin head
2) myosin releases actin
3) ATP -> ADP + P

Question 13

myofibril

Answer 13

a component of the animal skeletal muscle

long filaments that run parallel to each other to form muscle fibers

Question 14

sarcoplasmic reticulum

Answer 14

a specialized form of the endoplasmic reticulum that contains a high concentration of Calcium ions

covers the myofibrils

Question 15

sarcoplasm

Answer 15

the modified cytoplasm of myocytes (muscle cells)

Question 16

sarcolemme

Answer 16

the cell memebrane of a myocyte (muscle cell)

Question 17

each muscle cell contains many …

Answer 17

myofibrils

Question 18

muscles cells are also called…

Answer 18

muscle fibres

Question 19

explain the breakdown of muscles

Answer 19

each muscle is made up of many muscle cells/fibres
each muscle cell is made up of many myocil

Question 20

neuromuscular junction

Answer 20

the synapse between a motor neuron and a muscle cell

Question 21

what happens when the action potential reaches the neuromuscular junction?

Answer 21

acetylcholine is released into the synapse and depolarizes the muscle cell

Question 22

what is a motor unit

Answer 22

an individual motor neuron and all of the muscle fibers that it innervates

Question 23

what happens when the depolarization of the muscle cell reaches the sarcoplasmic reticulum?

Answer 23

calcium (Ca2+) is released

Question 24

what happens when calcium is released?

Answer 24

it binds to troponin, and tropomyosin changes confirmation

Question 25

what happens when tropomyosin changes conformation?

following the binding of Ca2+

Answer 25

the myosin-binding sites on actin are exposed

Question 26

what happens once the myosin-binding sites are exposed?

Answer 26

the myosin heads binds with these sites (on actin)

Question 27

explain the steps of muscle contraction

Answer 27

1) calcium binds to troponin, revealing the myosin-binding site on actin
2) myosin binds to actin
3) the powerstroke occurs, ADP and Pi dissociate from myosin
4) ATP binds to myosin, causing it to detach from actin
5) hydrolysis of ATP recocks myosin head into initial position

Question 28

what is responsible for the powerstroke?

Answer 28

the dissociation of ADP and Pi from myosin

NOT the hydrolysis of ATP

Question 29

what causes muscles relaxation

Answer 29

acetylcholine in the neuromuscular junction is degraded the the muscle cell repolarizes

caclium release stops, and the myosin binding sites are covered again by tropomyosin