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Musculoskeletal and Connective Tissue > muscles and bones biology > Flashcards

muscles and bones biology Flashcards

1
Q

muscle contraction - steps

A

neurotransmitter release –> postsynaptic ligand –> depolarization –> Ca2+ release from sarcoplasmatic reticulum –> troponinin C to tropomyosin system –> displacement of myosin on the actin filament –> myosin binds and hydrolyses ATP

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2
Q

muscle contraction - neurotransmitter release is caused by

A

action potential depolarization opens presynaptic voltage-gated Ca2+ channels, inducing neurotransmitter release

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3
Q

muscle contraction - postsynaptic ligand leads to

A

muscle cell depolarization in the motor end plate

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4
Q

muscle contraction - depolarization process

A

it starts from ligand binding –> depolariztion travels along muscle cell and down the T - tubule

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5
Q

muscle contraction - depolarization result to –>

A

depolarization of the voltage-sensitive dihydropyridine receptor, mechanically coupled to the ryanodine receptor on the sarcoplasmic reticulum –> conformation change
–> Ca2+ release from sarcoplasmic reticulum

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6
Q

muscle contraction - Ca2+ action (and mechanicals changes)

A

released Ca2+ binds to troponin C causing a conformation change that moves tropomyosine out of the myosin-binding groove on actin filaments

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7
Q

muscle contraction - myosin action

A

myosin release bound ADP and inorganic PO4(3-) –> displacement of myosin on the actin filament (power stoke) –> binding a new ATP causes detachment of myosin head from actin filament –> hydrolysis –> high energy position (cocked) for the next cycle

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8
Q

sarcomere anatomy - M line

A

M line: middle line

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9
Q

sarcomere anatomy - H band

A

myosin between myosin heads (in the middle of the sarcomere)

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10
Q

sarcomere anatomy - A band

A

all myosins (in the same sarcomere) (thick filaments)

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11
Q

sarcomere anatomy - I band

A

from the end of the myosins of the one sarcomere to the end of the myosins of the next sarcomere

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12
Q

sarcomere anatomy - Z lines

A

the lines of sarcomere

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13
Q

transverse (T) tubules?

A

extensions of plasma membrane part of juxtaposed with terminal cisternae (part of sarcoplasmic reticulum)

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14
Q

Terminal cisternae are

A

enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules

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15
Q

T tubules and Terminal cisternae - numbers

A

in skeletal muscle: 1 T + 2 terminal cisternae (triad)

in cardiac muscle: 1 T + 1 terminal cisternae (diad)

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16
Q

contraction - appearance of bands

A
  • shortening of H band + I band + sarcomere

- A band remains the same length

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17
Q

H band after contraction

A

shorter

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18
Q

A band after contraction

A

same

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19
Q

I band after contraction

A

shorter

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20
Q

sarcomere band after contraction

A

shorter

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21
Q

muscle contraction - postsynaptic ligand binding leads to muscle cell depolarization in the

A

motor end plate

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22
Q

muscle depolarization travels muscle cell and down the

A

T-tubule

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23
Q

muscle cells - T-tubule receptor

A

dihydropyridine receptor

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24
Q

muscle cells - sarcoplasmic reticulum receptor

A

ryanodine receptor

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25
Q

Types of muscle fibers

A
  1. type 1 muscle

2. type 2 muscle

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26
Q

sarcomere - thick filaments

A

myosin

27
Q

sarcomere -thin filaments

A

actin

28
Q

types 1 vs type 2 - functional characteristic

A

type 1 - slow twitch

type 2 - fast twitch

29
Q

types 1 vs type 2 - colour (why)

A

type 1 - red (increased mit and myoglobin)

type 2 - white (decreased mit and myoglobin)

30
Q

types 1 vs type 2 - metabolism (why)

A

type 1 - oxidative phosph (increased mit and myoglobin)

type 2 - anaerobic glyc (increased mit and myoglobin)

31
Q

muscle fibers with sustained contraction

A

type 1

32
Q

muscle fibers - weigh training results in

A

hypertrophy of fast-twitch (2) muscle fibers

33
Q

fast twitch muscle fibers - type?

A

2

34
Q

slow twitch muscle fibers - type?

A

1

35
Q

Osteoblasts action

A

build bone by secreting collagen and catalyzing mineralization

36
Q

bone mineralization is process in which

A

crystals of calcium phosphate are produced and laid down within the bone’s fibrous matrix

37
Q

Osteoblasts - differentiate from

A

mesenchymal stem cells

38
Q

Osteoblasts - differentiate from (where)

A

mesenchymal stem cells

in periosteum

39
Q

osteoclasts appearance

A

multinucleated cells

40
Q

osteoclasts action

A

dissolve bone by secreting acid and collagenases

41
Q

osteoclasts - differentiate from

A

monocytes

macrophages

42
Q

parathyroid hormone action on bone

A
  • low, intermittent levels –> anabolic effects (building bone) on osteoblasts and osteoclasts (indirect)
  • chronically increased PTH (1ry hyperparath) –> catbolic effect (osteitis fibrosa cystica
43
Q

estrogen action on bone

A
  1. inhibits apoptosis in osteoblasts

2. induce apoptosis in osteoclasts

44
Q

bone - estrogen deficiency –>

A

excess cycles of remodeling –> bone resorption leads to osteoporosis

45
Q

bone - multinucleated cells

A

osteoclasts

46
Q

bone - monocytes and macrophages are differentiate to

A

osteoclasts

47
Q

bone - mesenchymal stem cells are differentiate to

A

osteoblasts

48
Q

bone formation - types

A
  1. endochondral ossification

2. Membranous ossification

49
Q

bone formation - membranous ossification - which bones

A

bones of calvarium and facial bones

50
Q

bone formation - endochondral ossification - which bones

A

bones of axial and appendicular skeleton and base of the skull

51
Q

bone formation - membranous ossification - mechanism

A

woven bone formed directly without cartilage. Later remodeled to lamellar bone

52
Q

bone formation - endochondral ossification - mechanism

A

Cartilaginous model of bone is first made by chondrocytes. Osteoclasts and osteoblast later replace with woven bone and then remodel to lamellar bone

53
Q

woven bone is also called

A

fibrous bone

54
Q

in adults woven bone occurs after

A

fractures and in Paget disease

55
Q

smooth muscle contraction process

A

membrane depolarization –> L-type voltage gated Ca2+ channe –> increased intracellular Ca2+ –> increased Ca2+-calmodoulin complex –> activation of MLCK –> Myosin - p (+ actin) –> contraction (via cross bridging)

56
Q

MLCK

A

myosin-light-chain- kinase

57
Q

MLCK (myosin-light-chain- kinase) action

A

myosin+actin –> myosin-P+actin

58
Q

Smooth muscle cell - vasodilator

A

Nitric oxide (NO)

59
Q

Ca2+ vs NO on smooth muscle contraction

A

Ca2+ –> contraction

NO –> relaxation

60
Q

NO associated relaxation of smooth muscles - process

A

NO –> activation of Guanylate cyclase –> increased cGMP (from GTP) –> activation of MLCP –> Myosin+actin (no Pi) –> relaxation

61
Q

MLCP

A

myosin-light-chain-phosphatase

62
Q

MLCP (myosin-light-chain-phosphatase) action

A

Myosin-P+actin –> Myosin+actin

63
Q

MLCP vs MLCK according action and results

A

MLCP –> Myosin-P+actin –> Myosin+actin –> relaxation

MLCP –> myosin+actin –> myosin-P+actin –> contraction

64
Q

NO synthase - action

A

L-arginine –> NO

Musculoskeletal and Connective Tissue (19 decks)

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