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muscle stimulation Flashcards

1
Q

what regulates how big an axon will be?

A

the cell body

larger cell body means larger nucleus and larger muscle it ca innervate

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2
Q

what do large motor units innervate?

A

type IIB fibres: fast twitch glycolytic white

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3
Q

what do small motor units innervate

A

type I

slow twitch oxidative red muscles

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4
Q

define muscle tension

A

the force exerted by contracting muscle on a object

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5
Q

define load

A

the force exerted on muscle by a weight that need to be moved

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6
Q

developent of muscle tensio depends on?

A

the frequency of stimulation
sterngth of stimulation
degree of stretch

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7
Q

what is the latent phase?

A

no contraction

time taken for the impulse to rach to muscle

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8
Q

wha stages do muscles go through after a simple stimulus?

A

latent period
period of contraction
period of relaxation

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9
Q

whathapens during the period of contraction?

A

cross binding develops

sarcomre shortens

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10
Q

what happens in the relaxation period?

A

Ca levels in cytosol decrease due to SERA
cross bridges break
muscle returns to normal length

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11
Q

what is temporal summation?

A

second stimuli applied before relaxation period is finished then increased tensio develops

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12
Q

what happens if there is insufficient time between stimulations

A

subsequent twitches become larger
calcium not fully reteruned to base levels
contractions stronger, building
eventually reach a max tension though

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13
Q

what does repeated stimulation during relaxation periods cause?

A

results in a gradual increase in tension

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14
Q

what is incomplete or unfesed tetanus

A

repeated stimulation causing a gradual increase in tension resulting in a max tension of a bumpy plateau
there is a small amount of relaxation between each stimulus but not large

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15
Q

what is complete or fused tetanus

A

stimulation frequency is incrased before the relaxation period there are no signs of relaxation at all
complete tetnaus is reached
plateau is flat not bumpy

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16
Q

why in complete fused tetanus does there eventually come a fatigue period?

A

tension has to drop at soe point
lactic acid builds up leading to a pH drop
ATp is decerased
imbalance in ion concentrations

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17
Q

why are large cell bodys conected to large motor units

A

axon is bigger, ore dendrites and units that can be innervated

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18
Q

which motor units have the higher resistance

A

smaller cell bodys

larger ones have lots of ion channels and thus lower resitance, needs more to innervate it though

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19
Q

features of small motor units

A

higher resitance
low activation thersholds
innervated by small motor neurons
few ion channels

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20
Q

features of large motor units

A

low resistance
high activation thresholds
lots of ions channels
need longer stimulation

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21
Q

what does the sliding filament theory say about muscle tension

A

tension is related to the number of cross bridges that form

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22
Q

what is the length tension relationship?

A

everything, myosin and actin, need to be in optimal conformation in order for max tension
muscle keeps in optimal length by bones

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23
Q

what happens if muscle fibres arent in the correct conformation for contraction?

A

not as much tension or force is generated

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24
Q

what does anormal single stimualte do

A

gives single twitch

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25
what does multiple well spaces stimuli cause?
same tension
26
what does repeatedn tension cause?
staircase effects
27
explain the staircase effect
levels of Ca not reduce fully to base line muscle heats up heat increases enzyme rates heat makes muscle less stiff, energy used for contration and not to overcome the stiffness basis of why we need to warm up
28
two types of contractions
isotonic and isometric
29
define isometric
same length contraction but tension changes
30
define isotonic
same tension constant force contractions | contraction reaches a level and stays the same but legnth changes
31
how does an isometric contraction occur
connective tissue lengthens meaning the totoal muscle length remains the same
32
define fulcrum
point of movement and attachement
33
why have fulcrums
means smaller amounts of force are needed to move the joint than if the muscle was further away
34
what prevents over stretching
sensors called proprioreceptrs
35
where are proprioreceptos found
main muscles | interphase between musles adn tendons
36
what do propriorecetors do
stop over stetching | cause activation of gamma neurones in over stretching to stop it going further
37
what is the golgi tendon body?
sensory nerve endings between collagen fibres
38
two types of propoceptors
muscle spindles and goldi tendor organs
39
what are muscle spindles
burried among extrafusal fibres of the muslce and send infromation to the CNS about stretch
40
structure of a muscle spindle
enclosed in connective tissue capsule called a sfusal
41
difference between intrafusal and extra fusal fibres
extrafusal ones are for normal contractions | intrafusal ones are the spindles for stretch reception
42
role of muscle spindles during relaxation
extrafusal fibres at rest sensory neurones are always active sending signals to the CNS alpha motor neurons ativated to recieve input from the sensory spindles to the contractile cells extrafusal cells maintain cenrtain tension at rest
43
what is the role of muscle spindles during stretch
``` muscle stretches spindles elonngate increased signalling alpha nuereosns more actiated extrafusal fibres contract stretching reduced and spindles return to original length ```
44
how are muscle spindles used in reflexes
muscle spindles elongate and iniate action potential along sensory neurones these go to the CNS and synapses to cause muscle to contract no involve ment of the brain
45
most common muscle spindle reflex
striking of the patella tendon leads to lengthening of the quadriceps muscles
46
define GTO
golgi tendon organ sensory neurone endings located between muscle fibres and tendons proprioceptive sensory receptor organ that senses changes in muscle tension
47
what does the GTO do
prevetns over contraction of the muscles
48
how does the GTO work
sensory neurone activates inhibitory neurones in CNS | or inhibitory interneurons prevent activation of alpha neurones that would induce contraction
49
what are the stimuli for hypertrophy
nutrition hormones stress
50
what fibres are the mos trainable
type IIa fst twitch oxidsative glycolyitc red muslce they can take on characteritics of the other muscle type
51
define hypertrophy
increasing muscle size | increase in both cross- sectional area, more fibrils but also more length, more sarcomeres per myofibril
52
what is hyperplasia
number of muscle fibres increasing | not seen in adult humans
53
what are satellite cells
stem cells for muscle repair
54
how do satellite cells work?
when damage to the muscle is sensed they beocme activate the muscles make signals to tell the cells to migrate tot eh region of damage quiscent normally
55
how does muscle hypertrophy occur?
fibres split a they get larger to maintain minimal surface area to volume ration fibres stil share nuclei though
56
why do muscle fibres want a minimal surface area to volume ratio
allows nutrients to get in and out efficiently
57
what causes signals for muscles to grow?
nutrients hormonal environment mechanical load
58
what do the signals for muscle growth then cause in the cells?
gene transcription mRNA translation to increase myofibrillar protein content more building blocks made increases transciption
59
what are steriods
chemical messengers that are syntehsised from cholesterol | act on the nucleus of cells
60
what are anabolic steriods used for
enhance performance | maximise anabolic actions such as strength and muscle mass
61
what is mypfascial pain syndrome
muscle tissue disorders | pain caused by tightened bands of muscle fibres
62
what is fibromyalgia
chronic pain syndrome | affects mainly women
63
what is muscular dytrophy
inherited muscle wasting diseased | muscle enlarge with fat and connective tissue
64
what causes muscular dystrophy
mutation in dystrophyn this protein connects muscle to ECM and transmits electrical activity to ECM if the dystrophyn molecule isnt working properly there will be muscle damage
65
what are UMN
upper motor neurones | originate in the bae of the cortext of the brain
66
what are LMN
lower motor neurones | originate in the spinal cord
67
what do UMn and LMN do?
act as transtters to provide a chain of command for voluntary movments to muscles throughout the body
68
what happens in MND
motr neurone diease | chain of command between LMN and UMN brokwn as these neurones degenerate
69
motor neurone disease risk factors
genetic environmental lifestyle
70
what is ALS
amylotrophic lateral sclorsis
71
what happens to the body in ALS
muscle degeneration caused by degeneration of the cell body, axon and nerve damage stimulation decreases
72
how does ALS manifest
``` loss of strength atrophy twitches, fascicilations muscle cramps slow movements loss of dexterity ```
73
what happens with age
performance decreases less motor units less control
74
what role do muscle injuries have with age
in old animals, more succeptable for contraction induce injury they have a delayed and impaired recovery and structura and functional defects

Human physiology (21 decks)

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