muscle terms

Question 1

what does motor mean

Answer 1

term used in the nervous system to describe a neuron that controls a muscle

Question 2

epimysium

Answer 2

out layer membrane that covers the whole muscle

Question 3

perimysium

Answer 3

covering for the fascicles (10-100 muscle fibers that are in bundles) of the muscle fiber

Question 4

fascicle

Answer 4

bundle of muscle fibers

Question 5

endomysium

Answer 5

is inside each fascicle and separates each individual muscle fiber

Question 6

sarcolemma

Answer 6

plasma membrane of muscle cell

Question 7

tranverse (t) tubules

Answer 7

infoldings inside the sarcolemma that circle around myofibrils, and action potential travels along it to spread throughout the muscle

Question 8

sarcoplasm

Answer 8

cytoplasm in the muscle fiber containing glycogen and myoglobin

Question 9

myofibrils

Answer 9

bundle of filaments wrapped in sarcoplasmic reticulum, inside the sarcoplasm. is the striated contractile organelle

Question 10

sarcoplasmic reticulum

Answer 10

membranes that wrap around the myofibrils –> net pattern

Question 11

terminal cisternae

Answer 11

sac like structures in the sarcoplasm reticulum that stores and releases calcium

Question 12

what are the 2 types of myofilaments

Answer 12

actin (thin filaments) and myosin (dark filaments)

Question 13

sarcomere

Answer 13

“compartments” that contain myofilaments and that is responsible for contracting

Question 14

A band

Answer 14

spans the entire dark bands (thick filaments) area –> includes overlap

Question 15

I band

Answer 15

area with only thin filaments (light bands)

Question 16

H zone

Answer 16

area in the center of each band that has thick but no thin (no overlap)

Question 17

Z line/discs

Answer 17

separate one sarcomere from the other and holds the actin in place

Question 18

M line

Answer 18

in middle where myosin is held in place

Question 19

what are the 3 proteins in myofibrils

Answer 19

contractile (generates force during contraction), regulatory (switch the contraction process off and on), structural (keep thick and thin in their proper alignment)

Question 20

describe what one myosin molecule looks like

Answer 20

2 golf clubs twisted together
head is the golf club, the tail is the handles that point towards the M line

Question 21

what do the myosin heads contain

Answer 21

2 binding sites (actin and atp)
atp site hydrolyzes the atop to generate energy for muscle contraction

Question 22

describe actin molecule

Answer 22

form helix shape with myosin binding sites for myosin heads and contain regulatory proteins

Question 23

what are the 2 regulatory on actin

Answer 23

tropomyosin: cover the myosin binding sites
troponin: hold tropomyosin in place and binds calcium and changes shape

Question 24

what are the 2 functions of atp

Answer 24

activates myosin head and detaches flexed myosin head from actin

Question 25

axon terminal

Answer 25

end bulb filled w vesicles containing neurotransmitters

Question 26

synaptic cleft

Answer 26

space between axon terminal and motor end plate

Question 27

motor end plate

Answer 27

has receptors for NT and binds them

Question 28

neurotransmitters

Answer 28

chemical released from vesicles into synaptic cleft that bind to receptors in the motor end plate that create an electrical signal in the muscle

Question 29

describe what happens during contraction

Answer 29

1. myosin heads have atp binding site that works as an enzyme to hydrolyze atp into adp + p to store energy during contraction cycle + calcium is released into cytoplasm and binds to troponin-tropomyosin and causes them to shift to expose myosin binding sites 2. energized myosin head attaches to myosin binding site and releases hydrolyzed phosphate group (cross bridge is formed) 3. myosin head flexes and creates 45 deg angle. as it changes, it pulls the actin towards the center of the sarcomere and does a power stroke (comes from stored energy in myosin head) + adp +p falls off 4. myosin head detaches from actin only when another atp binds to it and atp reactivated head and returns it to 90 deg angle

Question 30

what is rigor mortis

Answer 30

when cross bridges don't disconnect due to lack of atp (3hrs after death)

Question 31

describe what happens at a synapse

Answer 31

1. act pot arrives at the synaptic end bulb 2. the depolarizing phase of the impulse opens the voltage Ca2+ gates that are in the membrane of the syn. end bulb --> Ca2+ flows in 3. Ca2+ in the cytoplasm triggers the fusion of the vesivle membrane with the cell membrane --> causing release of NT into the synaptic cleft 4. Nt binds to Nt receptors in the post syn. motor end plate and opens ion gated channels and depolarization creates an act pot in the post syn. muscle

Question 32

isotonic vs isometric contractions

Answer 32

isotonic: creates tensions and changes the length causing movement isometric: creates tensions with no change in length (hold)

Question 33

muscle twitch

Answer 33

a single stimulus-contraction-relaxtion cycle in muscle fiber

Question 34

wave summation

Answer 34

when many successive stimuli arrive before relaxation -> muscle tension is increased to a maximum (larger than in treppe)

Question 35

complete vs incomplete tetany

Answer 35

incomplete: quivering of muscle complete: smooth continuous contraction with no relaxation (rapid delivery of stimuli)

Question 36

treppe

Answer 36

when a second stimulus occurs after relaxation and continuously causes an increase in muscle response to a maximum

Question 37

recruitment

Answer 37

increase in muscle tension due to an increase in the motor units activated

Question 38

motor unit

Answer 38

group of muscle fibers controlled by a single motor unit

Question 39

muscle tone

Answer 39

tension in relaxed muscle

Question 40

stimulus contraction relaxation cycle

Question 41

what factors affect the force of a contraction

Answer 41

motor units and recruitment --> the number of muscle fibers activated and the frequency of neural stimulation to the muscle

Question 42

what does the muscle look like at rest (before contraction)

Answer 42

myosin heads are activated (in up right position) atp is hydrolyzed to adp + p app + p is attached actin active sites are covered by tryponin and actin + myosin is slightly overlapped calcium is in cisternae