LESSON 2 - skeletal muscle & human movement 1 Flashcards
skeletal muscle & human movement 1
What are the three types of muscle ?
Skeletal
Smooth
Cardiac
Describe skeletal muscles and their location
Voluntary and Skeleton
Describe smooth muscles and their location
Involuntary and within hollow organs
Describe cardiac muscles and their location
Involuntary and located within the heart
Describe the anatomy of muscles from the bone
Bone - tendon - muscle - fascicle - muscle fibres - muscle fibre - myofibril
How are bones attached to muscles ?
Tendon
What is the thin layer of the muscle tissue called ?
Epimysium
What is the fascicle surrounded by ?
The perimysium
What are muscle fibres made of ?
Bundle of myofybrils
Which layer is the epimysium ?
Outermost
Which layer is the endomysium ?
Under
Which layer is the perimysium ?
Between
What do skeletal muscles consist of ?
75% water, 20% protein, and the remainder is salts, enzymes, pigments, fats and carbohydrates
Name a trick to remember the order of muscles ;
Bigger the name, the smaller it is
What is a muscle fibres made up of ?
Bunch of myofibril
Between thick and thin filaments which one moves ?
Thin (actin)
Between thick and thin filament which one is actin /myosin ?
Thin = actin
Thick = myosin
What part of the sarcomere never has interaction with myosin ?
H zone
Which between the A band and H zone interacts with actin/myosin ?
A band
Which moves the thick or thin filament ?
Thin (actin)
Which does not move, the thick or thin filament ?
Thick (myosin)
What do myofilaments do ?
Allow muscles to contract
Which part of the myofilament have troponin ?
Actin
What binds to troponin causing the power stroke ?
Myosin heads
Where do the myosin tails and heads point toward ?
Tails = towards centre of sarcomere
Heads = sides of the myofilament band
What is actin attached to ?
The Z-line
Which is on the outside / inside between actin and myosin ?
Myosin in the middle and actin on the outside
the average muscle fiber contains how many sarcomeres ?
4500 sarcomeres
the average muscle fiber contains how many myosin ?
16 billion
the average muscle fiber contains how many actin filaments ?
64 million
a full muscle is made up of a bunch of …
muscle fascicles
between actin and myosin which has troponin surrounding them ?
actin
what does the mitochondria do within the muscle structure ?
produces energy
how does the mitochondria produce energy within the muscle structure ?
consuming oxygen
what is the sarcoplasm within the muscle structure ?
space that surround (fluid filled space)
what is the sarcolemma ?
membrane of the cell
what are the t-tubles within the muscle structure ?
(essentially) electrical wires
where do the t-tubules connect ?
connect from the brain to sarcoplasmic reticulum in regards to calcium
what does the sarcoplasmic reticulum do within the muscle structure ?
wraps around each myofibril
what triggers a muscle contraction ?
calcium
which type of muscle requires us to think about performing an action ?
the skeletal muscle system
what are the four main parts of the neuronal system that regulates movement in regards to the skeletal muscles ?
- brain
- spinal cord
- nerves
- t-tubles
which pathway does the neuronal system travel ?
descending (motor) pathway
between dorsal and ventral which is anterior / posterior ?
dorsal = posterior
ventral = anterior
what are the three major divisions of the nervous system ?
- brain and spinal cord
- cranial and spinal nerves
- somatic and visceral neurones
what do somatic and visceral neurones do ?
conduct impulses from receptors to CNS
which two systems work ascending and depending of each other ?
CNS and PNS
which two branches does the peripheral nervous system branch into?
sensory (afferent) nerves and effector (efferent) nerves
what do motor neurons do ?
conduct impulses from CNS to effectors
what two branches does the effector (efferent) nerves branch into ?
autonomic and somatic
between autonomic and somatic which is involuntary / voluntary ?
autonomic = involuntary
somatic - voluntary
“conduct impulses from CNS to cardiac/smooth muscle and glands”
involuntary
“conduct impulses from CNS to skeletal muscles”
voluntary
what two branches does the autonomic system branch into ?
sympathetic and parasympathetic
“fight or flight”
sympathetic
“rest and digest”
parasympathetic
what is a motor unit ?
single motor neuron and all the muscle fibers it innovates
within each muscle fiber how many neurons are present in each ?
one neuron
describe how the motor neuron travels starting from the spinal cord …
spinal cord - motor neuron (cell body) - travels descending through nerve - motor unit 1 - motor neuron axon - travel to its own individual muscle fiber
TRUE OR FALSE
“one impulse can innervate many different muscles fibers”
true
TRUE OR FALSE
“each muscle fiber generally receives input from only one neuron, yet a motor neuron may innervate many muscle fibers because the terminal end of an axon forms numerous branches”
true
define in your own words “neuromuscular junction”
nervous system & muscular system
where do nerve impulses travel ?
travel down axon
what is released at the axon terminal of neuromuscular junction ?
ACh
what does ACh stand for ?
Acetylcholine
what do myofibrils store ?
calcium
what does ACh trigger ?
an electrical potential on the sarcolemma
what happens if an electrical excitation threshold is reached ?
an AP is triggered
what happens what a transmembrane voltage is created ?
changed membrane potential
what does ACh do in regards to potassium and sodium ?
changes permeability of membrane to sodium and potassium
what helps release ACh at the synaptic vesicle ?
calcium
where is the action potential traveling through the neuromuscular junction ?
going down nerve
what happens once ACh binds to a ACh receptor ?
triggers a current that travels down / activates the t-tubles
what type of wave is traveling down the t-tubles ?
wave of depolarization
the wave of depolarization traveling down the t-tubles stimulates what ?
the sarcoplasmic reticulum
what does the sarcoplasmic reticule release once it is triggered by the wave of depolarization ?
calcium
what is the importance of calcium being released by the sarcoplasmic reticulum ?
allowing for actin / myosin to interact and cause a contraction
where does ACh travel from the synaptic vesicle ?
travels across the synaptic clef and binds
why do muscle fibres shorten ?
because myosin and actin interact in a way that generates tension and allows sliding of the filaments past each other without myofilaments changing length
what serves as the molecular motor to drive fiber shortening ?
energy from ATP
where does energy from muscles come from ?
ATP
what are the two states of how muscles create movement ?
relaxed state and contracted state
define the relaxed state …
- no actin-myosin interaction occurs at binding site
- myofilaments overlap a little
define the contracted state …
- myosin head pulls actin toward sarcomere center (power stroke)
- filaments slide past each other
- sarcomeres, myofibrils, muscle fibers all shorten
how many steps are there in the power stroke preform a power stroke ?
6
which step of the power stroke is “in the ready state, the myosin cross-bridge is tightly bound at a 45 degree angle to the actin filament”
1
which step of the power stroke is “ATP binds to myosin allowing it to release from the actin filament”
2
which step of the power stroke is “ATPase on the myosin hydrolyses that ATP to access energy, and the myosin head moves away from the actin filament. ADP and Pi remain bound to myosin”
3
which step of the power stroke is “the myosin head moves to 90 degrees and binds to a new actin molecule”
4
which step of the power stroke is “the myosin head released Pi, which initiates the power stroke, where it tilts back to 45 degrees, pulling the thin filament toward the center of the sarcomere”
5
which step of the power stroke is “after the power stroke the myosin head releases ADP and returns to the ready state. this process continues until the ends of the myosin filaments reach the Z-disks, or until Ca is pumped back into the SR”
6
what does myosin need in order to bind ?
ATP
what does calcium interact with in order to initiate a contraction ?
troponin
why does calcium need to interact with troponin ?
to release the binding site
what does it mean if an individual has less ACh ?
gets fatigued quicker
AP travelling down the t-tubels triggers the release of _____
calcium
does a release of calcium cause increase of force ?
yes
what is a biodex machine ?
measures force stimulating nerve to get a twitch
is there a “max” where sarcomeres can no longer be contracted ?
yes
within the length-tension relationship graph how many steps are there ?
5
what force is it when “↓ crossbridge interactions + ↑ shortening capability”
force 1
what force is it when “↑ crossbridge interactions + ↑ shortening capabilities”
foce 2, 3 and 4
what force is it when “↑crossbridge interactions + ↓ shortening capability “
force 5
what happens when pushing & pulling (of muscle and physical structure) is occurring ?
↑ APs = ↑ crossbridge interactions = ↑ shortening = ↑ force
if you have more AP what does this mean for force ?
more AP = greater force
what are dynamic contractions ?
muscle contractions with a fixed amount of weight
what are the three types of dynamic contractions ?
isometric, concentric and eccentric
what is isometric ?
no movement
what is concentric ?
shortening / flex
what is eccentric ?
lengthening / extended
how do we calculate force (N) specifically ?
load (kg) x gravitational constant (9.81m/s^2)
within a force-velocity relationship high force + ___ velocity …
low
within a force-velocity relationship big weight (mass) = ___ acceleration …
low
how do we calculate force (N) simplified ?
mass x acceleration
how do we calculate power ?
power = force x velocity
what is fatigue ?
a loss in the capacity of the muscle to develop force and/or velocity resulting from muscle activity under load
how is fatigue reversible ?
reversible by rest
how does fatigue occur ?
from interrupting the chain of events between the CNS → PNS → NMF → muscle fibers
what are some examples that can lead to fatigue in muscles ?
-reduced stored muscle energy (glycogen)
- impaired calcium release and re-uptake
- disturbance in T-tubles
- alterations in CNS neurotransmitters
