Studied by 3 people
4 Functions of skeletal muscles
Movement
Posture
Stabilize
Body heat
Epimysium
surrounds entire muscle (keeps shape)
Tendon
connects muscle to bone
Perimysium
wraps muscle fibers into fascicles
Endomysium
surrounds each muscle fiber
Fascicle
bundle of muscle fibers
Fiber
muscle cell
Myofibril
contractile organelles, makes up 80% of fiber, contains sarcomeres
Sarcomere
multiple units of myofilaments, contractile unit of actin and myosin
Actin
thin protein filament
Myosin
thick protein filament
Myofilament
one unit of actin/myosin filaments
Z-line
connects each myofilament
Order of muscle fiber parts from largest to smallest
1. muscle fibers
2. myofibrils
3. sarcomeres
4. myofilaments
Myoglobin
is the protein used to store oxygen in the muscle
Glycosomes
storage unit of glycogen (glucose)
T-tubules
an extension of the sarcoplasmic reticulum, continue to carry the electrical signal, allow communication so all sarcomeres contract at the same time
Sarcoplasmic Reticulum
help to carry the electrical impulse into the muscle, stores calcium
Neuromuscular Junction
where one nerve ending and one muscle fiber meet
Sodium
the sodium enters the muscle fiber and results in depolarization (loss of resting membrane potential)
Calcium
binds to troponin to allow myosin to connect to actin
1st step of muscle contraction
The neurotransmitter releases ach into the synaptic cleft
2nd step of muscle contraction
Ach binds to receptors on sarcolemma an creates action potential
3rd step of muscle contraction
Action potential travel to the t-tubules
4th step of muscle contraction
Electrical signal causes sarcoplasmic reticulum to release calcium
5th step of muscle contraction
Calcium binds to troponin on actin
6th step of muscle contraction
Myosin is able to bind to actin and create power stroke
7th step of muscle contraction
Sarcomeres shorten causing muscle contraction
8th step of muscle contraction
Signal ends and calcium is reabsorbed into sarcoplasmic reticulum
9th step of muscle contraction
Myosin disconnect from actin
10th step of muscle contraction
Actin returns to original position (lengthening)
11th step of muscle contraction
Muscle relaxes
Latent phase
when nothing is occurring (at beginning)
Contraction phase
when muscle is depolarized (the peak of the graph)
Relaxation phase
when the muscle relaxes (the down slope of the graph, after the peak)
Muscle twitch
is a brief contraction, most common in body, homeostasis
Sustained (tetanus)
the muscle does not relax, not sustainable in the body
Large motor unit
Large muscle, for board movements
Small motor unit
Small muscles, the finer movements (fingers)
Muscle tone
The healthy state of muscle, always semi-contracted, firm and ready to respond
Wave summation
muscle does not fully relax between each contraction, so beach contraction is stronger
Multiple motor unit summation (recruitment)
multiple motor units acting at the same time within a muscle
Muscle fatigue
The muscle can not contract, it has a lack of ATP, cramp
Aerobic exercise
an exercise that uses oxygen to make ATP(running)
Anaerobic exercise
does not use oxygen to make ATP, instead uses glucose/glycogen (swimming)
Isometric
muscle contraction occurs but stays the same length (wall sits, plank)
Isotonic
muscle contracts and shortens (running, walking, bench press)
Muscles have 3 types of fibers
Slow oxidative
Fast oxidative
Fast glycolytic
Muscle fibers
some areas have more of a certain type
activated at different times, when needed
Slow oxidative
used all the time
found in the back, neck, spine, posture
thin
Slow oxidative
slow contraction speed
lots of mitochondria
Slow oxidative
high blood flow
high myoglobin
Slow oxidative
small motor units
high aerobic endurance (low fatigue)
Fast oxidative
twitch movements, fast
lots of mitochondria
Fast oxidative
uses some glycogen
high blood flow
Fast oxidative
high myoglobin
medium motor units
Fast oxidative
not much endurance (medium rate of fatigue)
legs, arms
Fast glycolytic
very fast, fight or flight reaction
legs and arms
thick
Fast glycolytic
not many mitochondria
low blood flow
Fast glycolytic
low myoglobin
large motor unit
high fatigue (no endurance)
Benefits of exercise
-More oxygen flows to the muscle which means better endurance in those muscles and muscle tone
Endurance training
Grow more blood vessels to supply more oxygen
Make more myoglobin
Strength Training
More myofibrils (muscle stronger)
Contractions stronger
Muscle fibers swell
Muscle Twitch
Tetanus
Treppe
Wave Summation
Excitability
ability to respond to stimuli, ex. shivering
Contractility
ability to shorten forcibly (flexing)
Extensibility
ability to extend or stretch
Elasticity
ability to recoil and resume its resting length after stretching
Functions of connective tissue coverings
transmit the contraction from muscle fibers to the bone
contribute to muscle elasticity and reinforce/hold muscle together
provide route for blood vessels and nervous to and from the muscle (typically one artery and one nerve per muscle which branch once inside)
Functions of connective tissue coverings
contribute to muscle elasticity and reinforce/hold muscle together
Functions of connective tissue coverings
provide route for blood vessels and nervous to and from the muscle (typically one artery and one nerve per muscle which branch once inside)
Origin
less movable part of muscle attachment point, stationary
Insertion
movable part of a muscle attachment point
1st source of energy used
ATP
2nd source of energy used
Creatine
3rd source of energy used
Glucose
Oxygen Debt
difference of oxygen needed and oxygen given to muscles, owe muscle oxygen (causes deep breathing)
Oxygen Debt example
need 6.1 oxygen, only take in 1.2L, have a debt of 4.8L
Muscular dystrophy
group of muscle destroying disease
Steroids
enhance mass (raise oxygen carrying capability of muscles)
Note 
Flashcard (68)