Muscles III

Question 1

what do contracting muscles pull on to produce movement?

Answer 1

tendons

Question 2

what do muscles develop as their sarcomeres shorten?

Answer 2

tensions

Question 3

what must occur for sarcomeres to shorten?

Answer 3

thick filaments attach to thin filaments and pull them towards the centers of the sarcomere

Question 4

sliding filament theory

Answer 4

thick and thin filaments slide past each other and shorten sarcomeres explain muscle contraction

Question 5

what filaments past what filament?

Answer 5

thick filaments pass thin filaments

Question 6

z discs move closer together so sarcomeres

Answer 6

shorten

Question 7

during contraction widths of A bands remains

Answer 7

constant

Question 8

H zones contraction

Answer 8

disappear

Question 9

what happens to I bands during contraction

Answer 9

narrow

Question 10

what is the only portion which increases in width during contraction?

Answer 10

portion of filaments which overlap thick and thin filaments

Question 11

do filaments change in position or length?

Answer 11

lengths of filaments never change only their relative position change

Question 12

neuromuscular junction

Answer 12

the site of signal exchange

Question 13

physiology of muscle contraction

Answer 13

Calcium ions stored in sarcoplasmic reticulum receive stimulation from neuron → message sent through t-tubules causing change in sarcoplasmic reticulum (releases calcium ions) → calcium exposes the actin binding site allowing for cross bridges to form → ATP binds to myosin and broken down into ADP and phosphate → muscles undergo powerstroke and they contract → nervous system stops sending message to muscle cell (calcium goes back)
; roponin changes shape when calcium binds and displaces tropomyosin, ATP is required for release and continued contraction of muscle

Question 14

skeletal muscles are

Answer 14

voluntary

Question 15

skeletal muscle fibers are excited by

Answer 15

axons of somatic motor neuron

Question 16

each muscle fiber is controlled by

Answer 16

one motor neuron

Question 17

a motor neuron impulse stimulates an…

Answer 17

impulse in a muscle fiber

Question 18

neuromuscular junction

Answer 18

where the motor neuron communicates with the muscle fiber

Question 19

anatomy of the synapse

Answer 19

neuron, muscle cell, vesicles, ACh, synaptic cleft, MEP

Question 20

synapse

Answer 20

neuron communicating with another cell

Question 21

neuromuscular junction (NMJ)

Answer 21

synapse specifically used to communicate with muscle cell

Question 22

neuron

Answer 22

cell that sends the message

Question 23

muscle cell

Answer 23

receives the message from the neuron

Question 24

muscle cell receptor sites identify

Answer 24

neurotransmitters

Question 25

axon

Answer 25

sending end of the neuron

Question 26

where are vesicles present?

Answer 26

end of presynaptic neuron

Question 27

ACh

Answer 27

certain type of neurotransmitter used

Question 28

synaptic cleft

Answer 28

narrow space separating two cells; between muscle and synapse

Question 29

motor end plate (MEP)

Answer 29

region of sarcolemma which have many folds to increase the surface area

Question 30

myasthenia gravis

Answer 30

immune system produces antibodies attacking ACh receptors at the MEP; muscles become weak and tired due to abnormalities of contraction

Question 31

motor units

Answer 31

single motor neuron and the muscle fibers it controls

Question 32

motor units contain

Answer 32

only some of the muscle fibers it controls

Question 33

when a motor unit stimulates

Answer 33

all muscle fibers within it contract

Question 34

movements that require more force...

Answer 34

recruit more motor units

Question 35

small motor unit stimulating few muscles fibers provides

Answer 35

precise control

Question 36

eg of muscles using small motor units

Answer 36

eyes, hand

Question 37

motor units that exert a lot of power have

Answer 37

less precise control

Question 38

eg. of muscles with larger motor units

Answer 38

lower limbds

Question 39

benefits of multiple motor units

Answer 39

more precision, more powerful contraction, allows for different muscle actions to be performed