Muscles -- Lecture 21 (after Exam 3)

Question 1

muscle types:

what are they and examples?

Answer 1

cardiac muscle cell (striated)

skeletal muscle cell (striated)

smooth muscle cell (no striations)

Question 2

structure of skeletal muscle:

muscles are composed of…

Answer 2

bundled units of muscle cells called fascicles

Question 3

structure of skeletal muscle:

fascicles (definition)

Answer 3

bundles of 20-80 muscle cells called muscle fibers

Question 4

structure of skeletal muscle:

muscle fibers (definition)

Answer 4

cells that contain 4-20 myofibrils

Question 5

structure of skeletal muscle:

myofibrils (definition)

Answer 5

contain the contractile units that contract and relax during muscle movements

Question 6

structure of skeletal muscle:

myofibrils are composed of…

Answer 6

repeating units called sarcomeres

Question 7

structure of skeletal muscle:

sarcomeres (definition)

Answer 7

basic unit of contraction

separated by Z discs

Question 8

sarcomere contraction:

H bands (what are they and what happens to them as sarcomere contracts)

Answer 8

distance b/n actin filaments

shortens/disappears as sarcomere contracts

Question 9

sarcomere contraction:

I bands (what are they and what happens to them as sarcomere contracts)

Answer 9

distance b/n Z discs and myosin filaments shortens

the distance b/n Z disks shortens

a full contraction shortens muscle length by ~20%

Question 10

sliding filament model:

myosin motor proteins bind to the ___

Answer 10

actin

Question 11

sliding filament model:

___ bind to the actin

Answer 11

myosin motor proteins

Question 12

sliding filament model:

myosin motor proteins pull the ___ filaments closer together (power strokes)

Answer 12

actin

Question 13

sliding filament model:

___ pull the actin filaments closer together (power strokes)

Answer 13

myosin motor proteins

Question 14

sliding filament model:

the actin filaments slide down the ___

Answer 14

myosin filaments

Question 15

sliding filament model:

the ___ slide down the myosin filaments

Answer 15

actin filaments

Question 16

sliding filament model:

each power stroke costs ___

Answer 16

1 ATP/motor protein

Question 17

rigor mortis:

after death, lack of ___ causes the myosin motor proteins to become ‘stuck’ to the actin filaments

Answer 17

ATP

Question 18

rigor mortis:

after death, lack of ATP causes the ___ to become ‘stuck’ to the actin filaments

Answer 18

myosin motor proteins

Question 19

rigor mortis:

after death, lack of ATP causes the myosin motor proteins to become ___ to the actin filaments

Answer 19

stuck

Question 20

rigor mortis:

after death, lack of ATP causes the myosin motor proteins to become ‘stuck’ to the ___

Answer 20

actin filaments

Question 21

rigor mortis:

so muscles become ___ in place

Answer 21

frozen

Question 22

rigor mortis:

so ___ become frozen in place

Answer 22

muscles