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Physiology Exam I > Skeletal Muscle > Flashcards

Skeletal Muscle Flashcards

1
Q

sarcolemma

A

cell membrane

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2
Q

sarcomere

A

functional unit of muscle

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3
Q

sarcoplasmic reticulum

A

internal tubular structure where Ca++ is stored and released for excitation-contraction coupling

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4
Q

T tubules

A

carry electrical information deep into the cell

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5
Q

muscle fiber

A

basically a muscle cell

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6
Q

myofibril

A

bundles found in muscle fibers

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7
Q

titin

A

spring like projection

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8
Q

dystrophin

A

large protein that forms a rod that connects the thin actin filaments to a transmembrane protein

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9
Q

ryanodine receptor

A

Ca++ release channel in the Ca++ATPase pump

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10
Q

DHP receptors

A

voltage-senstive protein that has a conformational change when depolarized

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11
Q

Actin filament

A

anchored a Z liens

present in I bands

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12
Q

What does the actin filament contain

A

actin, tropomyosin, and troponin

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13
Q

Myosin filament

A

present in the A band in the center of the sarcomere
has 6 polypeptide chains, 1 pair of heavy chains, and 2 pairs of light chains
each molecule has 2 heads attached to 1 tail

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14
Q

What does the myosin filament contain

A

myosin

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15
Q

Sliding filament theory

A

The thin and thick filaments are sliding over each other. When it’s fully contracted, there is an opposite actin to every myosin head.

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16
Q

ATP in muscle contraction

A

ATP binds to myosin head, reducing it’s affinity for actin. It breaks down into ADP and Pi, causing the myosin head to go into the “cocked” position. After Ca++ binds to troponin C, the myosin ADP-Pi complex binds to actin. Pi gets released and you get the power stroke. To complete the cycle ADP gets released, but remember it is stuck in the rigid state (actin and myosin are still bound!) In order to relax, another ATP has to come along and bind.

17
Q

role of Ca++ in skeletal muscle contraction

A

Ca++ binds to troponin C which exposes an active site on actin so myosin can bind. When you lose the Ca++, tropomyosin moves back, covers the active site again.

18
Q

role of Ca++ATPase pump

A

The Ca++ATPase pump transports Ca++ from intracellular fluid into the SR interior, which keeps intracellular Ca++ low.

19
Q

role of calsequestrin

A

Ca++ is loosely bound to calsequestrin

20
Q

Phosphocreatine and creatine kinase

A

re-phosphorylates ADP to ATP using a high energy bond from phosphocreatine

21
Q

glycogen

A

can be metabolized to pyruvate with rapid production of ATP

22
Q

What type of motor units are in muscles that need fine control

A

very small (few muscle cells)

23
Q

What type of motor units are in muscles that do not need fine control

A

very large motor units

24
Q

How to produce graded muscle contraction

A
  1. Increase the number of motor units contracting at any one time - multiple motor unit summation.
  2. Increase the rate of stimulation of a single motor unit.
25
Q

Function of Dystrophin-Glycoprotein Complex

A

The complex adds strength to muscles partially by connecting fibrils to extracellular matrix.

26
Q

Duchenne muscular dystrophy

A

severe reduction in dystrophin in skeletal and cardiac muscle, X-linked recessive inheritance, usually fatal by 30 years of age

27
Q

Becker muscular dystrophy

A

less severe disease since functional dystrophin present but altered or reduced in amount

28
Q

Limb-girdle dystrophies

A

many different types associated with mutations of genes coding for other components of the dystrophin-glycoprotein complex and other muscle proteins

29
Q

Isometric contraction

A

muscle does not shorten during contraction

30
Q

Isotonic contraction

A

muscle does shorten during a contraction, but the tension on the muscle remains the same

31
Q

are individual muscle fibers connected by gap junctions/electrical synpases of skeletal muscle

A

no

32
Q

myofibrils

A

cylindrical structure ade up of an end-to-end chain of repeating unit, the sarcomeres

33
Q

what does sarcoplasm contain

A

mitochondira, nuclei, and ER

34
Q

sarcolemma

A

cell membrane of the muscle fiber

35
Q

what are the 2 components of the sarcolemma

A

plasma membrane

transverse tubules

36
Q

transverse tubules

A

extesnions of cell membrane

37
Q

what does the lumen of T tubules contain

A

extracellular fluid

Physiology Exam I (11 decks)

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