lecture 3, exam 1 study guide

Question 1

what is sarcoplasm?

Answer 1

gives the cell its shape
stores molecules for cellular processes

Question 2

what is sarcolemma?

Answer 2

membrane that surrounds striated muscle fiber cells

Question 3

what is a sarcomere?

Answer 3

ultimate force generator

Question 4

what are actin and myosin?

Answer 4

contractile (active) proteins

Question 5

what is a myofibril?

Answer 5

responsible for contraction of the whole muscle

Question 6

what is epimysium?

Answer 6

fibrous elastic tissue surrounding muscle belly
tough collagen fibers resistant to stretch

Question 7

what is endomysium?

Answer 7

connective tissue surrounding individual muscle cells/fibers
transfers contractile force from actin/myosin to tendon

Question 8

what is perimysium?

Answer 8

connective tissue surrounding bundle of muscle fibers.
tough and resistant to stretch

Question 9

what is fusiform?

Answer 9

fibers run parallel
designed for mobility, low force over long range
example: biceps brachii

Question 10

what is pennate?

Answer 10

fibers approach central tendon obliquely - larger number of fibers per area
larger forces
example: unipennate, bipennate, multipennate (triceps)

Question 11

what is physiologic cross sectional area?

Answer 11

amount of active proteins available to generate active force
thicker muscle generates more force

Question 12

what is the cross sectional area like in pennation angle?

Answer 12

perpendicular to fiber direction
pennation angle = 0 –> all force in tendon

Question 13

series vs parallel

Answer 13

series = all components connected end to end forming a single path
- length increases –> muscle grows in series

parallel = all components connected across each other –> all at the same time
- stronger muscle –> grows in parallel

Question 14

what is series elastic components (SEC)?

Answer 14

tissues attached end to end with active proteins - tendon, titin

Question 15

what is parallel elastic components (PEC)?

Answer 15

tissues that lie parallel with active proteins
epi/peri/endomysium

Question 16

what are noncontractile elements?

Answer 16

• structural proteins
• extracellular connective tissues (epi/peri/endo)

Question 17

what does stretching a muscle do?

Answer 17

elongates both parallel and series components
generates a stiffness or resistance within the muscle

Question 18

what 2 properties of muscle are components of plyometric exercise?

Answer 18

elasticity
viscoelasticity

Question 19

what is happening to the actin and myosin in the eccentric pre stretch phase?

Answer 19

pulling apart

Question 20

what is happening to the actin and myosin in the concentric phase?

Answer 20

pulling together

Question 21

what is amortization?

Answer 21

“time to rebound” when you bend down, you stay there –> you lost the elastic recoil

Question 22

do active proteins shorten?

Answer 22

no - slide back and forth, recruit more

Question 23

what is the active length-tension curve?

Answer 23

how sarcomeres of different lengths produce different force (A-D)

Question 24

what is the optimal length and force on the length-tension curve?

Answer 24

B-C (middle of graph)

Question 25

what are intrafusal muscle fibers?

Answer 25

inside the muscle spindles
contains receptors for sensory and proprioception
sends signals to CNS its being pulled

Question 26

what are extrafusal muscle fibers?

Answer 26

force generating structures
for contraction

Question 27

what is rate coding?

Answer 27

rate of sequential activation (action potentials)
smoothly increasing muscle force

Question 28

what is recruitment of motor units?

Answer 28

activation of specific motor neurons and its fibers

Question 29

which fibers are recruited first?

Answer 29

small recruited before large –> we tend to use less energy first if possible

Question 30

are more or less units required for eccentric? concentric?

Answer 30

eccentric = less units required
concentric = more units required for same force

Question 31

which motor unit type is recruited first? what size is the motor unit?

Answer 31

slow oxidative
- slower contractile characteristics
- little loss of force during sustained activation

small motor unit

Question 32

which motor type is recruited last? what size is the motor unit?

Answer 32

fast glycolytic/fast fatigable
- large forces required
- i.e. sprinters

large motor unit

Question 33

what happens in a concentric contraction?

Answer 33

length - shortens
torque - muscle > load
velocity - low load = max velocity
- increase load = max contraction velocity decreases

Question 34

what happens in an eccentric contraction?

Answer 34

length - lengthens
torque - load > muscle
velocity -
load greater isometric = muscle lengthens slowly
increased load applied = increase contraction velocity

at some point load level is too heavy to be resisted

Question 35

what happens in a isometric contraction?

Answer 35

length - constant
torque - muscle = load
velocity - no velocity