mechanical components of muscle fiber/ action potentials

Question 1

two mechanical components

Answer 1

myofibrils and myofilaments

Question 2

myofibrils

Answer 2

protein filaments long thread like structure that extend entire end of muscle fiber
made up of sacromeres put together

Question 3

sacromeres

Answer 3

functional and structural unit of muscle cell
smallest part that can contract
made of myofilaments

Question 4

z disks

Answer 4

filamentous network protein that serves as attachment site for actin (thin) filament in sarcomere

Question 5

region of sacromere (I band)

Answer 5

lighter stained
cotains z disk and extends to ends of mysoin filament

Question 6

region of sacromere ( A bands)

Answer 6

dark stained
overlaping myosin and actin (except at center)

Question 7

region of sacromere (h zone)

Answer 7

area in a band where myosin and actin do not overlap

Question 8

M line
region of sacromere

Answer 8

mdille of h zone—delicate fliaments holding myosin in place

Question 9

Actin Filament

Answer 9

thin filament
attach at either end of sacromere
two strands of fibrous actin to form double helix

Question 10

three parts of actin filament

Answer 10

G-actin
Troponin
Tropomyosin

Question 11

G actin
(actin flimanet)

Answer 11

has active site for myosin head bonding during muscle contraction

Question 12

Tropomyosin
(of actin)

Answer 12

protein that lies in grove of fibrous actin strand
when relaxed cover G actin binding sites
cannot contract until uncovers site

Question 13

Troponin
(of actin)

Answer 13

consists of 3 subunits
1. anchors troponin to actin
2. prevents tropomyosin from uncovering G site
3. Binds to calcium

Question 14

Tropomyosin/Troponin complex regulates interaction between G site and myosin T/F

Answer 14

True

Question 15

Myosin filament

Answer 15

thick filament
composed of myosin heavy chains to form rod and two myosin heads
look like golf club

Question 16

Myosin head functions (3)

Answer 16

1. can bind to active sites on G actin of Actin
2. attach to rod portion by hinge that can bend during contraction
3. are ATPase enzymes and actively breakdown ATP and release energy–part used to bend during contraction

Question 17

when muscle contracts- what happens to the length of mysoin and actin filaments

Answer 17

stays the same

Question 18

when muscle contracts what happens to the a zone

Answer 18

stays the same

Question 19

when muscle contracts what happens to the H zone

Answer 19

disappears

Question 20

resting membrane potential

Answer 20

charge of membrane at rest
inside of cell more negative at rest and outside more positive
ensured by NaK pump

Question 21

inside of cell more negative because

Answer 21

cumulation of large negative protein molecules
more K on inside than on outside

Question 22

outside of cell more postive bc

Answer 22

more Na on outside of cell than on inside

Question 23

NaK pump

Answer 23

for every three Na pumped out 2 K are pumped in

Question 24

depolarization

Answer 24

inside of plasma membrane becomes more positive (less negative) if change reaches THRESHOLD action potential triggered

Question 25

threshold

Answer 25

voltage gated Na channels open

Question 26

further depolrization

Answer 26

positive Na is rushed into the cell ; inside cell becomes more mostive

Question 27

repolarization

Answer 27

return of normal resting potential
originally drops lower than normal than rebounds
voltage gated K channels open and K is rushed into the cell

Question 28

All or nothing principle

Answer 28

all action potentials identical for a given excitable cell
if stimulus strong enough to reach threshold, all changes made without stopping
if not strong enough, no action potential produced

Question 29

propagate

Answer 29

action potential ant one spot stimulates action potential at next spot like dominoes

Question 30

action potential frequency

Answer 30

number of action potentials produced per unit of time
strong stimulus causes more action potentials