Module 4: muscle contraction and factors influencing force

Question 1

how do skeletal muscles power movement?

Answer 1

by converting ATP into mechanical energy

Question 2

what is the muscle hierachy?

Answer 2

1. Muscle Organ
2. Fascicle
3. Fiber
4. myofibril
5. sarcomere
6. myofiliment

Question 3

what are the 3 levels of connective tissue?

Answer 3

1. epimysium: dense, irregular surrounding entire muscle
2. perimysium: surrounding fascicle
3. endomysium: surrounding each fiber

Question 4

does muscular connective tissue create active or massive force?

Answer 4

passive

Question 5

what is a motor unit?

Answer 5

and alph motor neuron and all of te fibers it innervates

Question 6

what is a neuromuscular junction?

Answer 6

the connection between the axon terminal and muscle fiber

Question 7

what neurotransmitter is release at the neuromuscular junction?

Answer 7

Acetlycholine (ACh)

Question 8

what is the name of the muscle membrane?

Answer 8

sarcolemma

Question 9

what is End Plate Potential (EPP)?

Answer 9

the local depolarisation of the synapse and the muscle fiber

Question 10

which direction does the AP travel in EPP?

Answer 10

both directions

Question 11

is sarcolemma deep or superficial to endomysium?

Answer 11

deep

Question 12

what is sarcoplasmic reticulum?

Answer 12

the smooth ER in muscle tissue, used for storage of Ca2+

Question 13

what are the t-tubules attached to?

Answer 13

the sarcolemma

Question 14

what is the process of muscle contraction?

Answer 14

1. AP travels down motor neuron
2. ACh is released at the neurotransmitter junction
3. AP runs through the sarcolemma of the muscle
4. AP runs through the t-tubules of the muscle
5. Ca2+ is released from the sarcoplasmic reticulum
6. Ca2+ causes actin and myosin to bind
7. sarcomeres shorten
8. muscle contracts

Question 15

what is the cross bridge cycle?

Answer 15

when calcium ions binds to troponin, causing tropomyosin to move away from the myosin binding gates on the actin and causing a contraction through the hydrolysis of ATP.

Question 16

what are the 2 points of attachement for skeletal muscles?

Answer 16

1. origin: attachment that is relatively fixed, typically proximal
2. insertion: attachment more moveable, usually distal

Question 17

what is the difference between direct and indirect attachement of skeletal muscles?

Answer 17

1. Direct: epimysium fused to perioseum of bone or periochondrium of cartilage
2. indirect: connective tissue that wraps or extends beyond muscle as rope like tendons or sheet like aponeurosis

Question 18

what is aponeurosis?

Answer 18

the sheet like connective tissue that attaches
1. muscle to bone
2. muscle to muscle
3. muscle to fascia
4. muscle to tendon unit

Question 19

can muscles push?

Answer 19

no, muscles can only pull tendons or bones

Question 20

what are the 3 functional groups?

Answer 20

1. agonist (primary mover)
2. antagonist (opposes the agonist
3. synergist (assists agonist)

Question 21

what are the descriptors for muscle terminology?

Answer 21

1. muscle location
2. location of attachment
3. muscle shape
4. number of origins
5. muscle size
6. muscle action
7. muscle direction

Question 22

what is the measurment of force with muscles

Answer 22

Newtons

Question 23

what is the list of architectures for muscle groups?

Answer 23

1. circular
2. multipennate
3. bipennate
4. unipennate
5. parrallel
6. fusiform
7. convergent

Question 24

describe a circular muscle and give an example

Answer 24

a muscle that makes a dougnut shape (mouth)

Question 25

describe a multipennate muscle and give an example

Answer 25

a bundle of muscle fibers together to make a muscle organ (shoulder)

Question 26

describe a bipennate muscle and give an example

Answer 26

a muscle that has a tendon through the middle an the muscle fibers are on either side of the tendon (thigh)

Question 27

describe a unipennate muscle and give an example

Answer 27

a tendon that has 1 side of muscle fiber attached to it ( shin)

Question 28

describe a parrallel muscle and give an example

Answer 28

when the muscle runs parallel to the locations

Question 29

describe a fusiform muscle and give an example

Answer 29

a muscle in a shape of a spindle with a tendon running off the side (bicep)

Question 30

describe a convergent muscle and give an example

Answer 30

when the muscle has a wide origin and a narrow point (chest)

Question 31

what is a fascile?

Answer 31

the architecture of the muscle, linked to function

Question 32

what is pennate in a muscle describing?

Answer 32

higher force smaller range of motion higher PCSA

Question 33

what is parallel in a muscle describing?

Answer 33

lower force wide range of movement lower PCSA

Question 34

what is PCSA?

Answer 34

physiological cross examinational area

Question 35

what is the formula for PCSA?

Answer 35

PCSA= muscle volume/ fiber lengthe

Question 36

how do you find muscle volume and length in muscles?

Answer 36

volume: MRI length: ultrasound

Question 37

what is the sarcomere length?

Answer 37

the length/tension relaionship

Question 38

which component other than muscle keeps the muscle attached to the skeleton and passively produces force?

Answer 38

elastic

Question 39

what is the components of a contractile component?

Answer 39

1. muscle fibers 2. actin and myosin cross bridges

Question 40

what is the series elastic compoent? (SEC)

Answer 40

intracellular titin, tendons

Question 41

what is the parallel elastic component (PEC)

Answer 41

connective tissue, epimysium and perimysium., endo and cross bridge

Question 42

how does the sarcomere look when the muscle is relaxed?

Answer 42

small overlap of the mysoin and actin

Question 43

how does the sarcomere look when the muscle is contracted?

Answer 43

lots of overlap of mysoin and actin, little ofrce to be used

Question 44

what is muscle force influenced my?

Answer 44

1. number of neurons recruited 2. frequency of motor units discharging AP

Question 45

what does an AP firing in a muscle cause?

Answer 45

a twitch

Question 46

what does many twitches firing cause?

Answer 46

tetanus

Question 47

what are the 3 types of muscle fibers

Answer 47

1. slow twitch, light force, fatigue resistant 2a. intermediate twitch 2b. high twitch, large force, fatigues quickly

Question 48

what is hennemans size principle?

Answer 48

smaller units recruited first

Question 49

what are the different contraction types?

Answer 49

1. static: isometric (same length) 2. dynamic: concentric (shortening) 3. eccentric: eccentric (lengthening)

Question 50

what is the load difference, strongest to weakest in contraction types?

Answer 50

eccentric-isometric-concentric