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Kaitlyn BIO 201 > Lecture - Muscles > Flashcards

Lecture - Muscles Flashcards

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1
Q

What are the 4 properties of skeletal muscle?

A
  1. Excitability
  2. Contractility
  3. Extensibility
  4. Elasticity
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2
Q

What is the capacity to respond to nerve stimulation and contract called?

A

Excitability

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3
Q

What is contractibility?

A

The ability of muscles to contract (shorten)

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4
Q

How much can a muscle shorten during a contraction?

A

By up to 50% of the resting length

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5
Q

What is extensability?

A

A muscles ability to stretch or lengthen

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6
Q

When one muscle contracts, what often happens to another muscle?

A

Extension

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7
Q

A muscles ability to “spring” back into its original length after being stretched is called what?

A

Elasticity

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8
Q

What are the 3 functions of skeletal muscles?

A
  1. Movement of body
  2. Posture maintenance
  3. Heat production
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9
Q

How do skeletal muscles attach to bones?

A

Via tendons

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10
Q

What kind of muscle fibers subconsciously contract to keep the body upright?

A

Slow-twitch muscle fibers maintain posture

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11
Q

Which function of skeletal muscles is demonstrated by shivering in the cold?

A

Heat Production

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12
Q

What are the structural layers of a skeletal muscle from the inside out?

A
  1. Endomysium - surrounds myofiber (muscle cell)
  2. Perimysium - surrounds fascicle(bundle of myofibers)
  3. Epimysium - surrounds muscle (bundle of fascicles)
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13
Q

Endomysium, perimysium, and epimysium are all types of what kind of tissue?

A

Connective tissue

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14
Q

Where does a tendon insert into a bone?

A

Periosteum

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15
Q

What holds a muscle together and transmits blood vessels and nerves into the interior of the muscle?

A

Connective tissue/tendons

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16
Q

What are the components of a muscle cell from large to small?

A

Myofiber - bundle of myofibrils - myofilament

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17
Q

What is the name for the thousands of long, cylinder-shaped segments in a muscle cell?

A

Myofibrils

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18
Q

What is a sarcolemma?

A

The cell membrane of a muscle cell

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19
Q

What is the sarcoplasm?

A

The cytoplasm of a muscle cell

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20
Q

What is the tubular invagination of a sarcolemma that conducts nerve impulse deep into a muscle cell?

A

T-Tubule

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21
Q

Where in a muscle cell is calcium stored?

A

In the sarcoplasmic reticulum (SR) - a smooth ER

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22
Q

What is the name for the enlarged end of the SR that borders the T-tubule?

A

Terminal cisterna

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23
Q

What is a triad?

A

2 teminal cisterna + the T-tubule that runs between them; helps stimulate the release of calcium

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24
Q

A synapse is a site of communication between a neuron and which 3 places?

A
  1. another neuron
  2. a muscle - usually named a neuromuscular joint
  3. a gland
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25
Q

What is a neuromuscular junction?

A

The junction between a neuron and a muscle cell, there is a tiny gap

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26
Q

What bridges the synaptic gap in a neuron?

A

A neurotransmitter (think acetylcholine)

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27
Q

What are the two main categories of myofilaments?

A
  1. Thick filament

2. Thin filament

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28
Q

Actin, troponin, and tropomysoin are all examples of what kind of myofilament?

A

Thin filament - they are also all proteins

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29
Q

Example of a thick filament

A

myosin

30
Q

What is the name of the section of muscle measured from one Z disc to the next Z disc?

A

Sarcomere

31
Q

What is the functional unit of a skeletal muscle?

A

A sarcomere; contains stacks of myofilaments bound together

32
Q

4 Parts of the Sarcomere

A
  1. Z disc - end of each sarcomere, attachment site of actin proteins
  2. A band - dark band - made of myosin and overlapping actin
  3. I band - light band - made up on thin filaments only
  4. H band - contains only myosin
33
Q

What gives skeletal muscle its unique striations?

A

Its alternating A bands and I bands

34
Q

What are the 4.5 sources of ATP?

A
  1. Stored ATP - 6 seconds
  2. Creatine phosphate (CP) - 10 seconds
  3. Myoglobin
  4. Aerobic metabolism - 38 ATP
    .5 Anaerobic metabolism - 2 ATP
35
Q

Storage form of phosphate which can be quickly provided to convert ADP into ATP

A

Creatine Phosphate

36
Q

When is Creatine phosphate replenished?

A

When the muscle is at rest

37
Q

What is the muscle version of hemoglobin and what does it do?

A

myoglobin - binds oxygen and releases it as needed (when the lungs run out)

38
Q

What is the primary fuel source of actively contracting muscles?

A

Glucose through glycolysis

39
Q

Exceeding the ability of the lungs to supply oxygen

A

Oxygen debt (ex. sprinting) - this is why we pant after intense exercise

40
Q

What 4 things happen after exercise?

A
  1. “repayment” of oxygen debt through labored breathing
  2. Restoration of levels of Creatine phosphate
  3. Restoration of myoglobin levels
  4. lactic acid accumulated in muscles sent to liver where it is re-synthesized into glucose
41
Q

Why must lactic acid be quickly re-synthesized?

A

It dangerously lowers blood pH

42
Q

What 3 factors contribute to the strength of a muscle contraction?

A
  1. The size of the load (as told to the muscles by the brain’s guesstimate)
  2. The initial length of the muscle fibers (optimal length = optimal contraction strength)
  3. Frequency of stimulation (muscle memory)
43
Q

What are the 3 types of muscle contractions?

A
  1. Muscle twitch - single contraction 7-100 msec.
  2. Temporal summation - staircase phenomenon, 10-40 stimuli per second = stronger contractions
  3. Complete Tetanus - 40-50 stimuli per second, locked in contraction, very painful, cramp
44
Q

Which type of muscle contraction has only partial relaxation between contractions and builds on itself?

A

Incomplete Tetanus/Temporal Summation

45
Q

A classification of muscles that maintain the same tension throughout the contraction

A

Isotonic contraction (iso=same, tonic=tension)

46
Q

What are the two types of isotonic contraction?

A
  1. Concentric - muscle shortens (upward bicep curl)

2. Eccentric - muscle lengthens (lower bicep curl)

47
Q

What is an isometric contraction?

A

A contraction where the muscle maintains the same length throughout

48
Q

Your arm is extended and holding 5 pounds, someone adds an additional 5 pounds to your arm and you maintain the same position. What kind of contraction is this?

A

Isometric contraction

49
Q

You pick up a book from a table. What kind of contraction is this?

A

Isotonic contraction

50
Q

What are some cellular markers of slow-twitch fibers?

A

More mitochondria and myoglobin

51
Q

What kind of exercise stimulates cell enlargement by synthesizing additional myofilaments?

A

Resistance training (weight lifting)

52
Q

Hypertrophy

A

Cell enlargement

53
Q

Stimulates an increase in mitochondria and glycogen

A

Endurance training (aerobic exercise)

54
Q

What is a hereditary disease in males that causes skeletal muscle to degenerate and be replaced by adipose?

A

Muscular dystrophy

55
Q

What causes muscular dystrophy?

A

Loss of dystrophin, a protein that connects actin filaments with the cell membrane. Myofilaments slide over each other, but the membrane remains the same length causing membrane tears

56
Q

In which autoimmune disease do antibodies block receptors for acetylcholine (ACh) on the muscle cell at the neuromuscular junction (NMJ)?

A

Myasthenia Gravis

57
Q

What are the 3 different types of muscle cells?

A
  1. Skeletal - long, cylindrical
  2. Cardiac - striated, involuntary, branches, aerobic respiration
  3. Smooth - unstriated, spindle-shaped, small myocytes across fine control of small tissues like the iris of the eye
58
Q

Which type of muscle cell contracts slowly?

A

Smooth muscle - can maintain single contraction for a long time

59
Q

What has many calcium channels that allow extensive extracellular calcium to enter?

A

The sarcolemma in smooth muscle cells

60
Q

Why does the body need tendons and fascia?

A

For strong attachment of muscle to bone

61
Q

What causes post-workout soreness?

A

Lactic acid buildup from anaerobic respiration and microtears in the muscles

62
Q

How long does a skeletal muscle contraction last?

A

Up to 100 milliseconds (an eye twitch, 0.1 of a second)

63
Q

Why do skeletal muscles have more than one nucleus?

A

The nucleus codes protein using DNA and muscle cells have a lot of protein to code, manage, and replace

64
Q

How does a muscle shorten (does it “bunch up”)?

A

No, the actins slide over the myacins

65
Q

What is the stiffening of the muscles caused by lack of ATP called?

A

Rigor mortis

66
Q

How do creatine phosphate supplements work?

A

They give a little extra energy (ATP) in the form of phosphate

67
Q

What is a muscle cramp?

A

A cramp is complete tetanus, full extended contraction

68
Q

What is a muscle twitch?

A

It’s a single muscle contraction, a full contraction of relaxation

69
Q

Why are we only able to sprint for a short length of time?

A

We burn through our ATP and creatine phosphate, then we are stopped by our oxygen debt

70
Q

What makes “dark meat” dark?

A

It’s high concentration of myoglobin and mitochondria and oxygen; white meat is glycolytic

Kaitlyn BIO 201 (22 decks)

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