Lecture Three

Question 1

what is the function of a muscle

Answer 1

generate force, allows for movement

Question 2

what is the function of a motor neuron

Answer 2

signal muscle to contract allows for voluntary control

Question 3

why are muscles and motor neurons important for exercise

Answer 3

exercise requires coordinated movements involving multiple muscle groups and varied amounts of force

Question 4

what are the parts of a muscle

Answer 4

muscle- fasicle- fiber- myofibril- sarcomere- thick/thin

Question 5

what are the structures in a muscle fiber

Answer 5

sarcolemma transverse tubules sarcoplasmic reticulum mitochondria nucleus

Question 6

what is a muscle fiber that is enclosed by a plasma membrane called

Answer 6

sarcolemma

Question 7

what in the muscle stores calcium

Answer 7

sarcoplasma reticulum

Question 8

what is the purpose of calcium in the muscle

Answer 8

moves troponin off, allowing tropomyosin to dissociate and expose the actin for binding

Question 9

what is a thin filament

Answer 9

actin

Question 10

what is a thick filament

Answer 10

myosin

Question 11

facts of sarcomere

Answer 11

smallest functional unit of a muscle composed of thick and thin filament

Question 12

2/3 of all muscle protein is made of

Answer 12

myosin

Question 13

what are thin filament proteins

Answer 13

actin troponin tropomyosin

Question 14

what are the thick filament proteins

Answer 14

myosin

Question 15

what is the function of an alpha motorneuron

Answer 15

conduct impulse signals from CNS to muscle and initiate a contraction

Question 16

where are motorneurons grouped together

Answer 16

spinal cord

Question 17

motor neurons innervates what fibers

Answer 17

alpha motorneurons

Question 18

what composes a motor unit

Answer 18

neuron and muscle it innervates

Question 19

smaller motor unit size is used for

Answer 19

dexterity

Question 20

larger motor unit size is used for

Answer 20

force

Question 21

what is the neuromuscular junction

Answer 21

area where nerve “connects” to muscle fiber

Question 22

what signals are used in the neuromuscular junction

Answer 22

acetylcholine

Question 23

what maximizes contact for ACh release and capture in neuromuscular junction

Answer 23

shape and structure

Question 24

what are the four muscle fiber types

Answer 24

Type 1 : slow twitch Type 2a Type 2b Type 2x

Question 25

what happens for muscles with increased length

Answer 25

increased contraction velocity

Question 26

what happens for muscles with increased CSA

Answer 26

increased force

Question 27

if you increase CSA you increase what

Answer 27

force

Question 28

what proteins are in abundance in strong and big muscles

Answer 28

contractile

Question 29

what is muscle architecture

Answer 29

arrangement of muscle fibers relative to the axis of force generation

Question 30

what is an agonist

Answer 30

prime movers, responsible for the movement

Question 31

what is an antagonist

Answer 31

oppose the agonists to prevent overstretching of them

Question 32

what is a synergist

Answer 32

assist the agonists and sometimes fine tune the direction of the movement

Question 33

what is concentric

Answer 33

muscle shortens lowest force generated uses the most energy

Question 34

what is isometric contraction

Answer 34

muscle does not change length

Question 35

what is eccentric contraction

Answer 35

muscle lengthens generates greatest force/ resistive force uses the least amount of energy

Question 36

why does concentric contraction use more energy

Answer 36

takes more energy to overcome force opposing force

Question 37

what is muscle recruitment

Answer 37

the amount of muscle (individual fibers) that are actively contracting at a given point in time

Question 38

recruitment of muscle fibers is controlled by the

Answer 38

nervous system

Question 39

size of the motor unit is generally governed by the

Answer 39

fiber type of the muscle

Question 40

muscle fibers are recruited according to the size of the motor unit

Answer 40

one motor unit at a time

Question 41

what is the size principle of motor unit recruitment

Answer 41

small units to large units used by type one slow units to fast units/ firing freq

Question 42

why are slow motor units recruited first

Answer 42

it requires a smaller neural input to cause a slow motor neuron to reach its threshold and depolarize smaller axon hillock which is easier to depolarize

Question 43

slow motor units recruited first allows two things to happen

Answer 43

recruit slow, fatigue resistant fibers more often allows for a much finer gradation in force production which will enable greater motor control

Question 44

what is a muscle twitch

Answer 44

force produced from a single electrical signal

Question 45

what is contraction freq

Answer 45

number for signals per time period

Question 46

what is summation

Answer 46

progressive increase force with additional signals occurs bc leftover calcium

Question 47

what is tetanus

Answer 47

complete/ "fused" contraction in which force will not increase

Question 48

what is force (tension) directly related to

Answer 48

amount of actin-myosin that are interacting

Question 49

what is optimal length in the length-tension relationship

Answer 49

high tension due to maximal overlap of actin-myosin

Question 50

if velocity increases then force

Answer 50

decreases

Question 51

for velocity to increase, the cross bridge has to

Answer 51

detach faster and faster

Question 52

why cant force increase when velocity increases

Answer 52

fewer cross bridges are engaged at a given moment in time to generate force