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Biology 20 > Unit D4: Muscular system > Flashcards

Unit D4: Muscular system Flashcards

1
Q

myosin:

A
  • thicker than actin
  • myofilament
  • protein
  • composed of myosin molecules(proteins)
  • myosin molecule = 2 polypeptide chains wrapped around each other
  • end of the chain has a distinctive globular region(the head)
  • heads protrude at regular intervals out of muscle
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2
Q

location of the skeletal muscle:

A

attached to the skeleton

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3
Q

appearance of the cardiac muscle:

A

branched, striated cells
- intercalated discs

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4
Q

tropomyosin:

A
  • protein that wraps around the actin and blocks the active sites
  • stops myosin heads from binding to actin
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5
Q

sliding filament model:

A
  • a muscle contracts as a result of its thin actin filaments sliding over its thick myosin filaments
  • myosin and actin work together during a muscle contraction
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6
Q

why can muscles pull but cannot push?

A

Muscles shorten when they contract, so they can only pull, not push

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7
Q

botulism:

A

-toxins attack your nerves which results in weakness and paralysis of your muscles
- a potentially fatal muscular paralysis caused by a toxin produced by the bacterium Clostridium botulinum
- the toxin prevents the release of a muscle-stimulating compound released by muscle-related cells of the nervous system thus leading to paralysis

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8
Q

how do the myosin and actin act together in the sliding filament model?

A
  • the myosin head grabs into the actin filaments(flexes), pulling them z-lines closer together
  • this flex of the myosin filament shortens the myosin muscle fibre
  • actin filament slides past the myosin filament in the direction of the flex
  • ATP allows the myosin to detach from the actin and rest
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9
Q

what are the three types of muscle?

A

cardiac, smooth(visceral), skeletal(striated)

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10
Q

Energy for muscles:

A
  • ATP provides the energy for muscles to work
  • little ATP can be stored in muscles
  • SO muscles need MORE ATP
  • when ATP supply is low and O2 levels are low, lactic acid begins to accumulate, causing muscle pain!
  • 3 additional source of ATP: creatine phosphate, fermentation, aerobic cellular respiration
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11
Q

abundance of mitochondria in the cardiac muscle:

A

the MOST numerous
- the most mitochondria
- needs the most energy
- most ATP

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12
Q

when a muscle is relaxed what do the myosin heads do?

A

they are raised and ready but unable to bind to actin because of tropomyosin blocking the active site

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13
Q

when are calcium ions diffused by facilitated diffusion?

A

INTO the sarcoplasm from the sarcoplasmic reticulum

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14
Q

cardiac muscle cells:

A
  • striated, tubular, branched
  • one nucleus per cell
  • contracts involuntary
  • found in the walls of the heart
  • can tell by the vertical lines separated striations(intercalated disc)
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15
Q

blood vessels in skeletal bundles of muscle fibres:

A

supply oxygen and nutrients, remove cellular wastes

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16
Q

what causes the release of myosin from the actin active site?

A

the bind of ATP

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17
Q

myofilaments:

A

protein structures responsible for muscle contraction
- two types: myosin and actin

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18
Q

control of smooth muscle:

A

involuntary

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19
Q

myofibrils:

A

contractile unit in skeletal muscle
- 1 muscle fibre has hundreds of thousands of myofibrils

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20
Q

skeletal muscle in the body:

A
  • each muscle in the body lies along the length of a bone
  • a tendon(heavy band of tissue) attaches each end of a muscle to a different bone
  • blood vessels and nerves run between bundles of muscle fibres
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21
Q

Muscular dystrophy:

A

a collective term for several hereditary conditions in which skeletal muscles degenerate, lose strength and are gradually replaced by fatty and fibrous tissue that impedes blood circulation
- this in turn accelerates muscle degeneration in a fatal spiral of positive feedback
- the decrease in size and wasting of muscle tissue

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22
Q

all of the steps of muscle contraction with the sliding filament model:

A
  1. Calcium ions(Ca2+) diffuse from the sarcoplasmic reticulum to sarcoplasm through facilitated diffusion
  2. Calcium ions bind to troponin
  3. Troponin-tropomyosin complex shifts to expose active site
  4. Myosin head binds to actin active site and flexes, pulling z-lines closer to the center
  5. ATP attaches to myosin, myosin then detaches from actin, ATP hydrolyzes(ATP to ADH) which causes myosin head to return to cocked position
  6. Calcium ions detach from troponin, troponin-tropomyosin complex shifts back over the active site
  7. Calcium actively transported out from the sarcoplasm back to the sarcoplasmic reticulum
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23
Q

energy production of skeletal muscle:

A

aerobic and anaerobic

24
Q

parallel bundles in skeletal muscle:

A
  • each whole skeletal muscle is composed of parallel bundles
  • each bundle is composed of parallel units called fibres
  • blood vessels and nerves run between them
25
Q

location of the smooth muscle:

A

blood vessels, organs

26
Q

location of caridac muscle:

A

forms the heart

27
Q

actin:

A
  • type of myofilament
  • a protein
  • composed mainly of globular(circular) actin proteins
  • also contain some other proteins
  • thin
28
Q

skeletal muscle cells:

A
  • striated and tubular(not branched)
  • many nuclei
  • contract voluntarily
  • usually attached to the bones of the skeleton
29
Q

action of cardiac muscle:

A

rhythmic (beat of heart)

30
Q

skeletal muscle funtion:

A
  • muscles work by shortening when they contract and lengthen when they relax
    • produces body movement and support
    • maintains body temperature
  • skeletal muscles present in antagonistic pairs
    –> one muscle of the pair contracts to move the body part, the other controls the returm of the body part back to the original position
31
Q

sarcoplasm:

A

inside of skeletal muscle tissue
- inside myofil membrane

32
Q

what is a muscle?

A

-a muscle is a contractile tissue found in animals, that acts by contracting
- muscles only pull (contracts and relaxes)
- 3 types

33
Q

sliding filament model contraction:

A
  • the heads of two ends of myosin filament are orientated in opposite directions(opposite sides)
  • when heads attach to actin, they bend towards the center of the myosin
  • left and right sides are pulled towards to center and
  • both of the Z-lines move towards the center and contraction occurs(muscles sink)
34
Q

energy production of cardiac muscle:

A

aerobic respiration
(O2)
- not capable of anaerobic

35
Q

energy production of smooth muscle:

A

aerobic respiration
(O2)
- not capable of anaerobic

36
Q

nerves in skeletal bundles of muscle fibres:

A

trigger and control muscle contractions

37
Q

cardiac muscles:

A
  • found only in the heart
  • contracts and relaxes automatically
38
Q

troponin:

A

protein that binds to tropomyosin that binds to calcium ions which causes the troponin-tropomyosin complex to shift away from the active sites for the myosin heads on the actin

39
Q

control of cardiac muscle:

A

involuntary

40
Q

appearance of skeletal muscle:

A

long fibres with striations

41
Q

skeletal muscle fibres:

A
  • parallel units in the bundles
  • each fibre is a functional single-cell
  • up to 20 cm long
42
Q

appearance of smooth muscle:

A

long, cigar-shaped cells

43
Q

abundance of mitochondria in smooth muscle:

A

least numerous
- not a lot of mitochondria
- least amount of ATP

44
Q

skeletal muscles:

A
  • attached to bones by tendons
  • under voluntary control
45
Q

sarcoplasmic reticulum:

A
  • outside of myofil membrane and skeletal muscle tissue
  • high concentration of Calcium ions
46
Q

when are calcium ions actively transported?

A

OUT of the sarcoplasm and back to the sarcoplasmic reticulum

47
Q

action of the smooth muscle:

A

slow and sustained

48
Q

muscle cramps:

A
  • painful muscle spasms triggered by strenuous exercise, extreme cold, dehydration, salt imbalance, low blood glucose, or reduced blood flow
49
Q

action of the skeletal muscle:

A

fast(twitches)

50
Q

abundance of mitochondria in skeletal muscle:

A

numerous

51
Q

skeletal muscle structure largest to smallest(hierarchy):

A

muscle –> muscle-fibre buncle –> muscle fibre –> myofibrils(contractile unit) –> myofilaments

52
Q

sarcomere:

A

the basic contractile unit of muscle fiber
- includes actin and myosin
- the repeating functional units in muscle cells

53
Q

tetanus:

A
  • occurs when the stimuli are coming so quickly that there is no relaxation phase
  • a constant state of muscle contraction
54
Q

tendon:

A

heavy band of tissue that attaches each end of a muscle to a different bone

55
Q

smooth muscle:

A
  • found in the lining of many organs
    ex. stomach(churning), esophagus(peristalsis), blood vessels(arteries)
56
Q

control of skeletal muscle:

A

voluntary

57
Q

smooth muscle cells:

A
  • non-striated
  • one nucleus per cell
  • contract involuntarily
  • found in the walls of internal organs
  • lots of nuclei(small boundary)

Biology 20 (10 decks)

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