anatomy and physiology - muscle and bone Flashcards Preview

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Flashcards in anatomy and physiology - muscle and bone Deck (43)
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1
Q

what are t tubules

A

extensions of plasma membrane justaposed with terminal cisternae
part of the sarcoplasmic reticulum

2
Q

what type of muscle has a triad

A

1 t tubule and 2 terminal cisternae in skeletal muscle

3
Q

what type of muscle has a diad

A

1 t tubule and 1 terminal cisternae in cardiac muscle

4
Q

roel of t tubule in muscle contraction pelase

A

after ach released from opening of vg Ca in presynaptic and binds on post synaptic membranes causing cell depol in the motor end plate - depolarization travels along muscle cell and dowon the t tubule

5
Q

whats the roel of the dihydropyridine receptors in muscle contraction

A

are activated by depol from t tubules = mechanically couples to the ryanodine receptors ont eh SR – results in conformational change in teh RYR that causes Ca release from teh SR

6
Q

what happens after RYR receptors permit Ca out of the SR

A

release Ca binds to troponin C = leads to conformational change that moves torpomyosin out of the myoisn binding groove on actin filaments

7
Q

why cany myosin and actin interact when there is no calcium around

A

troponin C and Ca move tropomyosin out of the myosin binding grooves on the actin filaments

8
Q

what happens when myosin release ADP and organic Pi

A

displacement of myosin on the actin filamemt - poser stroke = contraction

9
Q

what changes size in contraction

A
NOT THE A BAND
H band
I band
length or sarcomere 
Z lines move towards the M line
10
Q

what happens when new ATP binds myosin

A

causes detachement of myosin head from actin

11
Q

what happens when ATP hydrolyzes to form ADp and Pi bound to mysoin

A

resets into cocked/high energy position ready for the next contraction cytle

12
Q

what happens when mysoin releases ADP and PI

A

power stroke, release from high energy state/cocked position and causes contraction

13
Q

describe role of ATP and myosin head

A

ATP bound = detaches myosin from actin
ATP hydrolyzes to form ADP and PI that are still bound to myosin = assumes high energy/cocked position
ADP and PI leave myosin - binds to actin and causes contraction leaving the high energy/cocked position.

14
Q

list the components of a sarcomere and what each represents pelase

A

H band- part of A band/mysoin heavy chains that is not interacting with actin chains
I band - width of actin not interacting with myosin. contains the Z line
A band - width of myosin heavy chainns, contains the mysoin chains and the H band and the M line
M line = connection of myosin heavy chaings
I line - connection of actin heavy chaings
H band decreases as more mysoin is interacting with actin
I band decreases as more actin is interacting with mysoin
A band - samezees

15
Q

boundaries of the sarcomere

A

Z line to Z line. hurah.

16
Q

on Em describe apperance of sarcomere

A

Z lines - darkest
I band - lighest area on both sides of Z line
H band - pale region around medium gray M line
M line - medim gray in middle of A band
A band - medium gray with H band and M line between I band.

17
Q

type 1 or type 2 fibres: slow twitch

A

one

18
Q

type 1 or type 2 fibres: fast twitch

A

two

19
Q

type 1 or type 2 fibres: red

A

one

20
Q

type 1 or type 2 fibres: white

A

two

21
Q

type 1 or type 2 fibres: lots of mitochondria

A

one

22
Q

type 1 or type 2 fibres: lots of myoglobin

A

one

23
Q

type 1 or type 2 fibres: oxidative phosphorylation

A

one

24
Q

type 1 or type 2 fibres: anaerboic glycosylation

A

two

25
Q

type 1 or type 2 fibres: increased at weight lifiting

A

hypertrophy of two

26
Q

type 1 or type 2 fibres: sustained contraction

A

one

27
Q

one slow ox

A

type one

28
Q

describe the relaxation of smooth muscle

A

NO - causes GC to convert GTP to cGMP - causes activation of MLCP - MLCP dephosphorylates myosin = relxation

29
Q

describe the contraction of smooth muscle

A

action potential opens L tyep vg CA channels - increases intracellualr calcium - complex of CA and calmodulin forms - causes activation of MLCK - phosphorylates myosine - myopsin-p + action = contraction via cross bidging

30
Q

what is endochondral ossification

A

cartilaginous modle of bones first made by chondrocytes – osteoblasts and clasts then replace with woven bone and then remodel that to lamellar bone

31
Q

what bones undergo endochondral ossification

A

axial and appendicular skeleton and base of skull

32
Q

what pathos has woven boneÉ

A

pagets disease - woven bone - pathologica fractures

33
Q

what is membranous ossification

A

no cartiliginous modle. woven bone is formed directly and is then converted to lamellar bone.

34
Q

what bones undergo membranous ossification

A

calvarium and facial bones

35
Q

name that bone cell: secrete collagen and catalyze mineralization

A

osteoblasts

36
Q

name that bone cell: multinucleated cells

A

osteoclasts

37
Q

name that bone cell: seceted acid and collagenases

A

osteoclasts

38
Q

name that bone cell: differentiate from mesenchyme in stem cells of periostem

A

osteoblasts

39
Q

name that bone cell: diffferentiated from monocytes/macropahges

A

osteoclasts

40
Q

what effect does PTH have on bone at low, intermittent levels

A

exerts anabolic effects/building of bone on osteoblasts and clasts (indirectly)

41
Q

what happens when PTH levels are chronically elevated

A

cause catabolic effects ie osteitis fibrosa cystica in primary hyperparathyroidisim

42
Q

effect of estrogen on bone

A

inhibits apoptosis of blasts

allows apoptosis of clasts

43
Q

what happens to bone when estrogen is def

A

surgery or post menopausal

excess cycles of remodelling and bone resorption = osteoporosis.