Biomechanics week 3 Flashcards
List the functional organization of skeletal muscle starting at the smallest.
sarcomere, myofibril, muscle fiber, muscle fascicle, skeletle muscle
what makes up sarcomere?
thick and thin filaments
What makes up myofibril?
a bunch of sarcomeres surrounded by a sarcoplasmic reticulum
What maks up muscle fiber?
it?s a bunch of myofibrils (many sarcomeres) surrounded by endomysium
What makes up muscle fascicle?
bundle of many muscle fibers surrounded by perimysium
What make up a skeletle muscle?
bundle of muscle fascicles surrounded by epimysium
What does perimysium surround?
muscle fascicle
what does endomysium surround?
muscle fiber
what does epimysium surround?
the muscle
list the 5 basic components of the neuromuscular junciton
motor neuron, motor end plate, synaptic cleft, synaptic vesicles, neurotransmitters.
what is the neuromuscular junction?
place where axon and muscle fiber connect, muscle fiber is surrounded by endomysium
what is released at neuromuscular junction to generate muscle contraction?
Ach, acetylcholine from synaptic vesicles
How is muscle allowed to relax after contraction?
enzyme acetycholineresterase breaks down the acetylcholine
What metal is necessary for contraction?
Calcium, helps open the motor units to cross bridge formation
what is the motor unit?
the functional connection between nervous and muscular system consisting of a single motor neuron and all the muscle fibers it controls (could be more than one)
How many muscle fibers can be innervated by one neuron?
several
How many motor neurons can innervate a single muscle fiber?
many neurons can act on a single fiber, they may all have different purpose
Fine motor control?
about 20 muscle fibers per neuron
Strength control?
about 1000 muscle fibers per neuron
What is muscle twitch?
single brief stimulus to a muscle that produces a quick cycle of contraction and relaxation lasting less than 1/10 second
can a muscle twitch do work?
no, its to small to do usefull work
Treppe is what?
relaxation that is complete before next stimulus of muscle, but each contraction is a bit stronger than before.
What is wave summation?
Temporal summation, where second stumulus is applied before relaxation is complete so that the next contraction is greater than if it was treppe
Tetanus is what?
Higher frequency of stimulaiton, the relaxation between contractions is reduced.
what is incomplete tetanus?
Can produce peak tension during rapidly alternating cycles of contraction and partial relaxation
Complete tetanus is what?
sustained maximal contraction at peak tension
What tetanus is typical of normal muscle contraction?
complete tetanus
What are the three phases of twitch?
latent, immediately after contraction, contraction where tension is increasing, and relaxation where tension is decreasing
what frequency of stimuli can cause treppe?
10-20 stinuli/sec, after a few they hit aplateau that they do not rise above
what is the frequency of wave summation?
20-40 stimuli/second, with each one arriving before the previous twitch is finnished
During what tetanus, do muscle fibers partially relax between contractions?
incomplete tetanus
what tetanus occurs at max frequency with no relaxation between contractions.?
conplete tetanus at 40-50 stimul a second
Rate muscle respones in order of force of contractions and rate of stimuli
single twitch, treppe, wave summation, incomplete tetanus, complete tetanus
What are the three functional classifications of neurons?
sensory
motor
interneuron
What type of neuron is sensory?
afferent - impulses go from receptors to the CNS
What type of neuron is motor?
efferent - impulses go from CNS to effector sites:
glands,
muscles
organs
What is an interneuron?
transmit impulses from neuron to neuron
What are the three type of nerve fibers?
A, B, and C nerve fibers, with A fibers further divided into subtypes
what are the fastest nerve fiber types?
the A fibers, they are myleinated
What are the 4 subtypes of the mylenated A fibers?
Speed from fastest to slowest: A-alpha, A beta, A gamma, A delta,
Where would A-alpha fibers be found?
efferent motor neurons and muscle spindel afferents.
What fibers have the largest diameter?
- Its counter intuitive but the fibers with the larges diameters are the fastest
- A alpha fibers are fastest, 100m/s
what fiber detect skin temp and pain or noxious stimuli?
The slowest A fibers:
A delta fibers, at 15m sec
What fiber are motor efferent to the muscle spindle?
A gamma, at 20 ms
What does the A beta fiber do?
Afferent mechanoreceptors at 50 m/s
- touch
- pressure
what are B fibers used for?
sympathetic:
- preganglionic fibers,
what types of nerve fibers are mylenated?
the two fastest fibers, both A and B fibers, C fibers are super slow and unmyleinated
Where are C fibers found?
Sympathetic postganglionic fibers:
- pain,
- burning
- and aching,
- itching .
How does the Type I - IV nerves types line up?
They are in order of largest and fastest to the slowest: Type 1 -Aa, Type II - Ab, Type III- A gamma Type IV- C, the slow unmylenated
what are the 5 basic components of the spinal cord reflex arc?
sensory receptor, sensory neuron, interneuron, motor neuron, effector organ
what is the point of the basic functional unit of the nervous system, the reflex arc?
automatic response to stimulus without conscious thought, save time because the brain isn’t required to be involved
Proprioception?
sense of positon and movement of body without using visuon
what are the three mechanoreceptior that detect proprioception?
muscle spindle receptors,
golgi tendon organs,
joint kinesthetic receptors.
what are muscle spindle fibers made of?
modified muscle fibers enclosed in capsule called intrafusal muscle.
what is extrafusal muscle fiber?
voluntary skeletal muscle
what would a spindle fiber detect?
Two things:
- Rate of muscle fibers are stretched
- Length of muscle stretch
what are the two types of intrafusal fibers?
Nuclear bag and nuclear chain fibers
What is the nuclear bag in the centeral part of fiber sensitive to with its striated contractile parts?
Nuclear bag: sudden rate of change in muscle length
what neuron type sends input to nuclear bag fibers?
gamma motor neurons go to Nuclear bag of muscle spindle fiber
Where are chain fibers located?
spread chain like in center of fiber and attached to the ends of the nuclear bag
what are chain fibers sensitive to?
Chain fibers of muscle spindle are sensitive to steady changes of length of the muscle
what is the nuclear chain or bag fibers of the spindle sensitive to?
Bag - sudden changes,
Chain - steady changes
is ther a non contractile region of the muscle spindle receptor?
Yes, the center part, wraped in sensory nerve that sends info to CNS
what are the type of sensory nerve endings of spindle receptor?
Primary ending - Type I Aa
Secondary ending type II Ab
which sensory nerve ending of spindle responds to overall length of muscle fiber?
Secondary type II, A-beta responds to overall length change of muscle fiber
What does primary ending type I A spindle respond to?
Primary Type I is sensitive to rate ofchange in fiber length
If the center of the spindle is wrapped in type IA and type II neruons, what neruons send info to spindle and where?
Gamma motor neurons, coming in to the muscle, slowest of the fast ones nerves, at the ends of the spindle fibers, give message to contract
Why is spindle importaint?
helps us keep balance contracting extrafusal muscles without us thinking about it when necessary
Is the spindle always set the same or can it change?
Gamma motor neurons let brain preset the sensitivity of spindle to stretch.
What part of brain controls the stretch response of spindle fibers?
Cerebellum controls stretch response to spindle fibers,,
- it regulates muscle tone
Where is a golgi tendon organ located?
Located at junction of tendon and muscle its the encapsulated nerve endings
what does golgi tendon organ detect?
- force of muscle contraction,
- tendon tension, an
- prevent contraction of muscle,
What does golgi play role in?
- muscle tone imbalance,
- muscle spasms, and
- tender points
What type of innervation for Golgi?
Sensory only
- Type IB
what does golgi detect?
- Tendon tension
- rate of change
What does the dynamic response respond to?
dynamic response responds to quick stretch
What does the static response respond to?
Postural changes:
-Static response responds to sustained or gradual increase in tension
What proprioceptors cause involuntary muscular relaxation?
golgi tenton organs cause involuntary relaxation
Where is spindle located?
Spindle is inn muscle fiber while golgi in in tendon
Type of innervation for spindle?
sensory and motor while golgi only has sensory
Spindle detects?
muscle length and rate change
What proprioceptors cause involuntary muscle contraction
spindle fibers. can cause involuntary muscle contraction while Golgi causes involuntary muscle relaxation
What are the 4 types of joint kinesthetic receptors?
Small Ruffini,
Pacini,
Large Ruffini,
Free nerve endings
Where would small ruffini be located, 3 places
- Fibrous capsule of synovial membrane
- capsular/cruciate ligaments and
- knee menisci
Where would pacini receptors be located 5 places
Fibrous capsule, ligaments, knee menisci, adipose tissue, annulus fibrosis cervical discs
Large Ruffini is what?
golgi tendon organ so its in the tendons
Where are large ruffini located?
ligaments,
Capsular between fibrous and synovial layers,
menisci, and
cervical discs
Where are free nerve endings found?
Free nerve endings, respond to rapid and sustained pressure: capsule, fat pads, ligaments and menisci
What are joint kinesthetic receptors?
encapsulated and free nerve endings and stretch receptors
What do joint kinesthetic receptors detect?
direction, acceleration, pressure, strain, postural change, skin receptor input
What three reflexes do proprioceptors use to affect tone?
quick stretch,
reciprocal inhibition,
autogenic inhibition
Quick stretch reflex uses what proproceptor?
- muscle spindal- Monosynaptic,
- sensory neuron, then to alpha motor neuron, then to muscle
What is the action of the quick stretch reflex?
Contraction of stretched muscle
Proprioceptor of Recipical inhibition?
Muscle spindles, same as is used for quick stretch reflex
What is the response for Recipical inhibition?
Inhibits muscle (relaxes) that is opposite of the one being contracted.
Path of recipical inhibition
- stretch muscle,
- spindel afferent neruron to Spinal cord,
- inhibitory interneuron to relax antagonist
Autogenic inhibition uses what proprioceptor?
golgi tendon organ is used for autogenic inhibition.
Response for autogenic inhibition is what?
Inhibitory response in mucle that is too tense either via shortening or lengthing muscle
Sequence for Autogenic inhibiton
- Stretch golgi,
- Type IB afferent ,
- Inhibitory neuron relax agonist,
- Excitatory interneuron conract antagonist.
