anatomy and physiology - muscle and bone

Question 1

what are t tubules

Answer 1

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

Question 2

what type of muscle has a triad

Answer 2

1 t tubule and 2 terminal cisternae in skeletal muscle

Question 3

what type of muscle has a diad

Answer 3

1 t tubule and 1 terminal cisternae in cardiac muscle

Question 4

roel of t tubule in muscle contraction pelase

Answer 4

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

Question 5

whats the roel of the dihydropyridine receptors in muscle contraction

Answer 5

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

Question 6

what happens after RYR receptors permit Ca out of the SR

Answer 6

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

Question 7

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

Answer 7

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

Question 8

what happens when myosin release ADP and organic Pi

Answer 8

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

Question 9

what changes size in contraction

Answer 9

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

Question 10

what happens when new ATP binds myosin

Answer 10

causes detachement of myosin head from actin

Question 11

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

Answer 11

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

Question 12

what happens when mysoin releases ADP and PI

Answer 12

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

Question 13

describe role of ATP and myosin head

Answer 13

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.

Question 14

list the components of a sarcomere and what each represents pelase

Answer 14

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

Question 15

boundaries of the sarcomere

Answer 15

Z line to Z line. hurah.

Question 16

on Em describe apperance of sarcomere

Answer 16

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.

Question 17

type 1 or type 2 fibres: slow twitch

Answer 17

one

Question 18

type 1 or type 2 fibres: fast twitch

Answer 18

two

Question 19

type 1 or type 2 fibres: red

Answer 19

one

Question 20

type 1 or type 2 fibres: white

Answer 20

two

Question 21

type 1 or type 2 fibres: lots of mitochondria

Answer 21

one

Question 22

type 1 or type 2 fibres: lots of myoglobin

Answer 22

one

Question 23

type 1 or type 2 fibres: oxidative phosphorylation

Answer 23

one

Question 24

type 1 or type 2 fibres: anaerboic glycosylation

Answer 24

two

Question 25

type 1 or type 2 fibres: increased at weight lifiting

Answer 25

hypertrophy of two

Question 26

type 1 or type 2 fibres: sustained contraction

Answer 26

one

Question 27

one slow ox

Answer 27

type one

Question 28

describe the relaxation of smooth muscle

Answer 28

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

Question 29

describe the contraction of smooth muscle

Answer 29

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

Question 30

what is endochondral ossification

Answer 30

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

Question 31

what bones undergo endochondral ossification

Answer 31

axial and appendicular skeleton and base of skull

Question 32

what pathos has woven boneÉ

Answer 32

pagets disease - woven bone - pathologica fractures

Question 33

what is membranous ossification

Answer 33

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

Question 34

what bones undergo membranous ossification

Answer 34

calvarium and facial bones

Question 35

name that bone cell: secrete collagen and catalyze mineralization

Answer 35

osteoblasts

Question 36

name that bone cell: multinucleated cells

Answer 36

osteoclasts

Question 37

name that bone cell: seceted acid and collagenases

Answer 37

osteoclasts

Question 38

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

Answer 38

osteoblasts

Question 39

name that bone cell: diffferentiated from monocytes/macropahges

Answer 39

osteoclasts

Question 40

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

Answer 40

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

Question 41

what happens when PTH levels are chronically elevated

Answer 41

cause catabolic effects ie osteitis fibrosa cystica in primary hyperparathyroidisim

Question 42

effect of estrogen on bone

Answer 42

inhibits apoptosis of blasts

allows apoptosis of clasts

Question 43

what happens to bone when estrogen is def

Answer 43

surgery or post menopausal

excess cycles of remodelling and bone resorption = osteoporosis.