• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

57 Cards in this Set

  • Front
  • Back
What are the 5 functions of skeletal muscle?
1- Produce Movement
2- Maintain body posture and position
3- Support soft tissues
4- Guard entrances and exits
5- maintain body temperature
Name the 5 levels of muscle organization in decending order
Skeletal muscle
Muscle fasicles
Muscle fibers
What is 1?
Motor Axon
What is 2?
Motor end plate
What is 3?
What is 4?
What is 5?
What is 6?
Transverse T tubule
What are the two proteins that make up sarcomeres?
Myosin (thick fillament)
Actin (thin fillament)
Name the structures of myosin and describe what energy form this structure is in.
1- actin binding site
2- ATP site
3- Hinge
4- two tails
High energy
Name the structures on actin
1- Tropomyosin
2- Myosin binding site
3- G actin
4- Troponin
What regulates the binding site on actin?
Describe the way that Ca++ regulates the binding site on actin
Ca++ is release from the sarcoplasmic reticulum
Ca++ binds to the troponin complex
Tropomyosin moves off the myosin binding sites of the actin filament
Describe molecular muscle contraction
1) Ca++ hs been released from the SR, boundto troponin, and caused the active sites on the actin molecules to be exposed.
2) A molecule of ATP is bound to the myosin head
3) ATP is hydrolyzed to ADP and Pi, which remain bound to the myosin
4) myosin head "cocks", or assumes its high energy position
5) Myosin head attaches to the active site of the actin molecule
6) Pi is released from the myosin head
7) The myosin head pivots, returning to it's low energy form, producing the "power stroke"
8) The myosin and actin are in a rigor state and the ADP moleule is released from the myosin head
Describe the entire mechanism of skeletal muscle fiber contraction.
1) action potential travels down the motor neuron to the neuronal terminal
2) ACh is released from the neuron
3) ACh binds to nicotinic receptors which cause an efflux of K+ and and influx of Na++, causing the cell to depolarize
4) a new action potential propogates along the muscle fiber cell membrane.
5) Action potential enters the fiber via the transverse T tubules.
6) Ca++ channels open in the SR, releasing Ca++ into the cytosol.
7) Ca++ binds to troponin, causing tropomyosin to slide off of the active sites on the actin.
8) Molecular mechanism of actin and myosin movement.
Describe the latent phase of a muscle twitch.
The muscle action potential travels along the muscle fiber and into the T tubules
Ca++ channels in the SR open
Ca++ floods into the cytosol
Ca++ binds to troponin
Tropomyosin moves off of the myosin binding sites on the actin
Is there tension during the latent phase?
no tension
How long does the latent phase last?
A few miliseconds
Describe the contraction phase of a muscle twitch.
Myosin heads attach to the actin and do the "power stroke"
Myosin heads bind a new ATP, release from the actin, re-cock, reattach, and perform another "power stroke"
this repeats a few times
Is there tension during the contraction phase?
increased tension
How long does the contraction phase last?
About 50 miliseconds depending upon the fiber type
Describe the relaxation phase.
Ca++ is pumped back into the SR
Tropomyosin covers up the myosin binding sites on the actin
myosin is no onger able to bind to actin.
Is there tension in the relaxation phase?
Decrease in tension
How long does the relaxation phase last?
about 50 miliseconds, depending upon the fiber type
Are twitches capable of summation?
What is tetanus and what kind of tetanus is always achieved in normal muscle fiber contraction?
Sustained contraction
Complete or fused tetanus
What kind of contraction is this?
What kind of a contraction is this
What is a motor unit?
a group of muscle fibersthat are all controlled by the same motor neuron
What is motor unit recruitment?
Increasingly greater forces are required from a muscle. A few motor units contract initially and progressively more motor units become active until maximum tension is achieved when all motor units are contracting.
What is motor unit rotation?
At sub-maximal tensions, motor units will alternate activity, allowing rest periods and prolonging the time with which the muscle can stay tonically contracted.
What is the size principle of motor unit recruitment?
When motor units are recruited, small motor units are recruited first and the progressively larger motor units are recruited as more tension is required.
Why are small motor units recruited first?
As the interneuron begins to fire, the motor neurons with the smalles cell bodies will reach their threshold membrane potential (-55mv) before motor neurons with larger cell bodies.
What happens when you increase the load on a muscle?
The velocity which with the muscle fibers are shortening decreases.
What does the phosphagen system use for fuel?
ATP and creatine phosphate
How many moles of ATP can the Phosphagen system produce per minute?
How long can the phosphagen system supply fuel for muscles?
9 seconds
What does the glycogen-lactate system (anaerobic system) use for fuel?
glycolysis and fermentation
How many moles of ATP per minute can the glycogen- lactate system produce?
How long can the glycogen- lactate system supply fuel to the muscle?
90 seconds
What does the aerobic system use for fuel?
glycolysis, pyruvate decarboxylation, the krebs cycle, and the ETC
How many moles of ATP per minute can the Aerobic system produce?
How long cal the aerobic system supply fuel to the muscle?
Unlimited duration, until nutrients last
Describe type I (slow-oxidative) muscle fibers
Slow speed of contraction
longer time to fatigue
High oxygen use capacity
low glycolysis capacity
many mitochondria
many capillaries
abundant myoglobin
red color (dark meat)
low glycogen content
Describe type IIa (fast- oxidative) muscle fibers
Fast speed of contraction
intermediate time to fatigue
high oxygen use capacity
intermediate glycolysis capacity
many mitochondra
many capillaries
abundant myoglobin
red color (dark meat)
Intermediate glycogen content
Describe type IIx (fast-glycolytic) muscle fibers
Fast speed of contraction
Shorter time to fatigue
Low oxygen use capacity
High glycolysis capacity
fewer mitochondria
fewer capillaries
less abundant myoglobin
white color (white meat)
High glycogen content
What are the major contributors to fatigue in oxidative fibers?
Glycogen depletion
increased temperature
What are the major contributors to fatigue in glycolytic fibers?
Lactate accumulation (maybe)
mechanical injury to muscle fibers
lack of blood supply
Increased temperature
What is central fatigue?
"tiredness" mediated by the CNS
What occurs in true neuromuscular fatigue?
Depletion of acetylcholine stores from motor neuron termini.
Skeletal muscle is at a ________ and must produce forces in _______ of the actual force that gravity is directly producing on the load.
Because skeletal muscle is at a disadvantage it permits _____ and _____ shortening of the muscle to result in the ______ and _____ movement of a load
Small and short
Long and fast
How many nucluei do smooth muscle cells have?
Becuse smooth muscle develops tension slowly and also relaxes slowly it causes:
longer contractile response
In smooth muscle what do actin and myosin radiate from?
Dense bodies
Describe the steps for smooth muscle contraction
1- Ca++ enters cytosol from the Extracellular fluid and from SR.
2- Ca++ binds to calmodulin in the cytosol
3- Ca-calmodulin activates myosin light chain kinase
4- myosin heads are activated (phosphoylated my MLCK)
5- Phosphorylated myosin attaches to actin filaments and complete the "power stroke"
Why does smooth muscle take longer to contract versus skeletal muscle?
The use of enzymes