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Biology > Chapter 11: Musculoskeletal System > Flashcards

Chapter 11: Musculoskeletal System Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

3 main types of muscle

A

skeletal muscle, smooth muscle, cardiac muscle

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2
Q

skeletal muscles are involved in […]

A

voluntary muscle control

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

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3
Q

which muscles are striated

A

skeletal

cardiac

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4
Q

which muscles are NOT striated

A

smooth muscle

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5
Q

which muscles are multi-nucleated

A

skeletal

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6
Q

which muscles are uni-nucleated

A

smooth

cardiac

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7
Q

involuntary muscle type(s)

A

cardiac muscle

smooth muscle

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8
Q

basic contractile unit of skeletal muscle

A

sarcomere

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9
Q

sarcomere

A

basic contractile unit of skeletal muscle

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10
Q

sarcomeres are made up of…

A

thick (myosin) filaments
thin (actin) filaments

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11
Q

what regulates the actin-myosin interactions?

A

troponin and tropomyosin

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12
Q

myofibril

A

a component of the animal skeletal muscle

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

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13
Q

sarcolemma

A

the cell membrane of a myocyte (muscle cell)

phospholipid bilayer

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14
Q

sarcoplasm

A

cytoplasm of myocytes (muscle cells)

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15
Q

each muscle cell contains many …

A

myofibrils

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16
Q

muscles cells are also called…

A

muscle fibres

17
Q

What is the sarcoplasmic reticulum?

A

a specialized smooth endoplasmic reticulum responsible for regulating cytosolic calcium levels in the muscle cell

surrounds the myofibrils

18
Q

explain the breakdown of muscles

A

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

19
Q

neuromuscular junction

A

the synapse between a motor neuron and a muscle cell

20
Q

what happens when the action potential reaches the neuromuscular junction?

A

acetylcholine is released into the synapse and depolarizes the muscle cell

21
Q

What is the sarcolemma?

A

the fine, delicate membrane that surrounds each muscle fibre

22
Q

What are T-tubules

A

invagintions of the sarcolemma
transmit the action potential from sarcolemma to sarcoplasmic reticulum

23
Q

What happens when the action potential reaches the t-tubules

A

it triggers the sarcoplasmic reticulum to open its calcium channels, causing them to flow down their concentration gradient into th cytosol

24
Q

what causes the calcium channels in the sarcoplasmic reticulum to close?

A

the depolarization of the cell ceases

25
Q

what happens to calcium when the action potential ends?

A

active transport calcium pumps sequester the calcium ions back into the SR

26
Q

what is a motor unit

A

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

27
Q

what happens when calcium is present in the cytosol?

A

it binds to troponin, and tropomyosin changes confirmation

28
Q

what happens when tropomyosin changes conformation?

following the binding of Ca2+

A

the myosin-binding sites on actin are exposed

29
Q

what happens once the myosin-binding sites are exposed?

A

the myosin heads binds with these sites (on actin)

30
Q

explain the steps of muscle contraction

A

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

31
Q

what is responsible for the powerstroke?

A

the dissociation of ADP and Pi from myosin

NOT the hydrolysis of ATP

32
Q

What causes the myosin head to detach from actin?

A

binding of ATP to myosin head

32
Q

What happens when ATP binds to myosin?

A

the Myosin head detaches from actin

33
Q

what causes muscles relaxation

A

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

34
Q

What happens when ATP is hydrolized?

A

the myosin head cocks back to its original resting position

Biology (14 decks)

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