Shared Flashcard Set

Details

FABio Exam #2
Anatomy and biomechanics
76
Anatomy
Graduate
09/09/2014

Additional Anatomy Flashcards

 


 

Cards

Term
Epimysium
Definition
surrounds entire surface of muscle belly; separates it from other muscles; tough structure of tightly woven bundles of collagen fibers that are resistive to stretch
Term
Perimysium
Definition
divides muscle into fasicles; tough, relatively thick and resistive to stretch
Term
Endomysium
Definition
surrounds individual muscle fibers; relatively dense meshwork of colagen fibers
Term
"Walk-Along" Theory of Contraction
Definition
  1. Before contraction, ATP cleaved by myosin head, head is extended
  2. TT complex binds with Ca to reveal actin active site
  3. Myosin head binds to actin site
  4. Power Stroke (cocked spring)
  5. ADP and P- released from head, new ATP binds, head detaches
  6. ATP cleaved by myosin head, head is extended
  7. Cycle Repeats
Term
Musculotendinous Unit
Definition
Spring-like elastic component (tendons) in series with a contractile component (contractile proteins) that is in parallel with another elastic component (epi, peri, endomysium)
Term
Describe the stretch factor of Musculotendinous Unit
Definition
Stretch produces tension (stored energy) in the elastic components (primarily tendons) which recoils when the stretch is released
Term
Describe the viscoelastic properties of the Musculotendinous Unit
Definition
Viscoelastic properties allow further elongation (creep) and a decrease in tension (stress-relaxation) when a stretch is held for a period of time
Term
4 Elastic components that are distensibly and elastically valuable
Definition
  1. Tend to keep the muscle in readiness for contraction and assure that muscle tension is produced and transmitted smoothly during contraction
  2. Assure that the contractile elements return to their resting positions when contraction is terminated
  3. Help prevent the passive over-stretch of the contractile elements when these elements are relaxed
  4. Absorb energy proportional to the rate of force application and to dissipate energy in a time-dependent manner
Term
Twitch
Definition
response of a muscle to single motor nerve impulse
Term
Latency Period
Definition
time from stimulation to the rise in muscle tension (represents the time to take up the "slack" in the elastic components)
Term
Contraction Time
Definition
period from the start of tension to peak tension
Term
Relaxation Time
Definition
period from peak tension to zero tension
Term
Treppe Effect
Definition
(AKA the staircase effect) graduated series of increasingly vigorous contractions that results when a series of identical stimuli is applied to a muscle
Term
Summation
Definition
mechanical responses to successive stimuli that add to the initial response; the greater the frequency of stimulation the greater the tension produced in the muscle up to a maximum
Term
Tetanus
Definition
the development of maximal tension as a result of summation beyond which no further increases in stimulation frequency will increase tension
Term
Gradation
Definition
gradual increase in tension produced by increased stimulation frequency and the number of motor units activated
Term
What are two ways to smoothly increase the force produced by the muscle?
Definition
  1. Increase stimulation rate
  2. Recruit more (and larger) motor units
Term
Isometric
Definition
muscle length does not change
Term
Example of an isometric contraction
Definition

Plank, wall squat, holding luggage

(No mech.work is performed; no movement is produced; stabilizes jt. position or posture; muscle work is performed; energy dissipated as heat; initial isometric phase to all dynamic contractions; greater tension than concentric due to the greater number of cross-bridges developed and activation of more motor units)

Term
Concentric
Definition
muscle shortens
Term
Example of concentric muscle contraction
Definition

"up" phase of arm curl

(muscle force greater than resistance force)

Term
Eccentric
Definition
muscle lengthens
Term
Example of eccentric muscle contraction
Definition

"down" phase of arm curl, walking downstairs

(resistance force greater than muscle force; max. tension developed (cross-bridges); greater chance of producing DOMS (delayed-onset muscle soreness)

Term
Isokinetic
Definition

same velocity (no acceleration)

"slow and controlled" contractions

Term
Isotonic
Definition

same muscle tension

*doesn't really exist due to changing leverage of the joints; selectorized machines attempt to match muscle force profiles using cams*

Term
Isoinertial
Definition

same external resistance

(must overcome inertial first)

Term
What effects the force generated within the sarcomere?
Definition
the greater the number of crossbridges the greater the force generated
Term
What is the ideal resting length of a muscle fiber?
Definition

 

the length that allows the greatest number of crossbridges and therefore the greatest potential force. 

Term
What is the first phase of a muscle activation vs. the length of the sarcomere?
Definition

 

Actin is overlapping, z discs abutting myosin so very little interaction with actin is possible (active insufficiency) 

Term
What is the second phase of a muscle activation vs. the length of the sarcomere?
Definition

End of optimal myosin-actin orientation

 

Term

What is the third phase of a muscle activation vs. the length of the sarcomere? 

 

Definition
Beginning of optimal myosin-actin orientation.
Term
What is the forth phase of a muscle activation vs. the length of the sarcomere?
Definition

 

Muscle is stretched so far that actin-myosin interaction is not possible (passive insufficiency) 

Term
What is the Length-Tension Relationship?
Definition
the number of cross-bridges determines amount of force that can be developed
Term
What happens if you increase of decrease the length in a Length-Tension Relationship?
Definition
(from its ideal resting length) deceases force production
Term
What are the active and passive tension and combination of the two factors in the Length-Tension Relationship?
Definition

Active Tension from contractile proteins

Passive Tension from stretch of elastic components (the high levels are most apparent over two-joint muscles)

 

Total Length Tension Curve is a combination of both passive and active tension and varies considerably between muscles of different structure and function 

Term
What is the relationship between the internal torque and elbow joint angle?
Definition

 

Internal torque greatest at about 75 degrees.


In the upright position the external torque caused by gravity is greatest in midranges of elbow flexion as well.

Term
What is the relationship between the internal torque and hip joint angle?
Definition

 

Internal torque greatest around 0 degrees

Similar angle at which the hip abductor muscles are most needed in the single-limb support phase of walking

Rarely is maximal torque needed near maximal hip abduction 
 
Term
Where do muscles produce their strongest contractions in the ROM?
Definition
at the middle phase of the ROM
Term
Which "arm" of the muscle AND resistance changes throughout the ROM
Definition
the moment arm
Term
What does gravity-based resistance depend on in terms of the internal torque and joint angle?
Definition

depends on the limb's relationship to the line of gravity vector.

 

Other forms of resistance depends on the limb's relationship to the line of resistance

Term
What is the relationship between force and velocity?
Definition

they have an inverse relationship.

 

As velocity increases, force produciton decreases

 

Eccentric relationship not as smooth as concentric

Term
What is the relationship between contractile velocity and force production?
Definition
they are inversly related
Term
Eccentric Contractions
Definition

can produce greater force at similar (negative) velocities

–  Greater average force produced per cross-bridge as they are pulled apart

–  A more rapid reattachment phase of cross-bridge formation

–  Passive tension produced by the elastic components 

Term
What is a long basic pattern of muscle architecture and an example?
Definition

sarcomeres in series, designed for velocity and excursion (proportional to length)

 

Ex: Sartorius

Term
What is a thick basic pattern of muscle architecture and an example?
Definition

sarcomeres in parallel, designes for force production (proportional to CSA)

 

Ex: quadriceps

Term
What is maximal force potential of a muscle proportional to & its physiologic effects?
Definition

the sum of the cross-sectional area of its fibers

 

the cross-sectional area reflects the amount of active proteins available to generate a contradiction force rather than just the cross-sectional area of the muscle (different for fusiform vs. pennate)

Term
How does the angle of pennation effect the force transmitted to the tendon?
Definition

The fibers that attach at 0 degrees (parallel) have ALL force transmitted to the tendon

 

Fibers that attach at an angle greater than 0 degrees have LESS force transmitted to the tendon

Term
At 30 degrees, what percent force is to the tendon?
Definition
86%
Term
At what pennation angle are most muscles at?
Definition
0-30 degrees
Term
Which muscle types produce greater maximal force and why?
Definition

Pennate muscles produce greater force than fusiform muscles because they can fit more fibers into a given length of muscle

 

*So force production is increased even though less force is transmitted since physiologically cross-sectional area increases significantly*

Term
When and in what way is it best to be stretched so that more work can be performed?
Definition
Contracting immediately after being stretched and in the eccentrically contracted state RATHER than isometrically
Term
Why is it better to be stretched in the eccentrically contracted state?
Definition
Due to energy stored in the elastic and contractile components
Term
What cycle does the prestretching work performed activate?
Definition
the stretch-shortening cycle
Term
What is an example of prestretching work?
Definition
Vertical jump test (squat vs. countermovement)
Term
If there is an increase in muscle temperature, what is the result?
Definition
  • Increase in conduction velocity and frequency of stimulation and hence muscle force metabolism.
  • Greater enzymatic activity of muscle metabolism (increasing efficiency of muscle contraction).
  • Increased elasticity of collagen (enhancing extensibility of the muscle-tndon unit
Term
What are 2 ways muscle temperature is increased?
Definition
  1. Increase in blood flow such as during a warm-up
  2. Heat production generated by metabolism, by the release of energy during contraction and by friciton of the contractile components
Term
What happens to the body at low temperatures? (below 50 degrees)
Definition
maximum shortening velocity and isometric tension are inhibited due to a decrease in pH (acidosis)
Term
What is fatigue?
Definition
A drop in muscle tension following prolonged stimulation
Term
In fatigue, what is the relationship between stimulation frequency and ATP?
Definition
Stimulation frequency outpaces the muscle's ability to regenerate ATP.
Term
What is the relationship between fatigue and tetanus?
Definition
Fatigue occurs more quickly during tetanus
Term
How can ATP regenerate to restore the muscle tension?
Definition
Rest of the muscle
Term
What 2 things does fatigue result in?
Definition
  1. Lack of coordination of movement (Reduce accuracy control and contractile velocity)
  2. Redistribution of loads in tissue
Term
4 Components of "Slow" Twitch (Type 1) Fiber
Definition
  1. Smaller
  2. More extensive blood vessel system
  3. More mitochondria
  4. Large amounts of myoglobin
Term
5 Components of "Fast" Twitch (Type II) Fibers
Definition
  1. Larger
  2. Extensive SR for rapid release of Ca2+
  3. Lots of glycolytic enzymes
  4. Less extensive blood supply
  5. Fewer mitochondria
Term
What are the 3 Types of Fibers and what are their relationship to fatigue?
Definition

Type I = Slow Oxidative (fatigue resistance)

Type IIA = Fast Oxidative Glycolytic (relatively fatigue resistant)

Type IIB = Fast Glycolytic (fatigues easily)

Term

T/F: 

  1. Muscles are often mixed with more than one type due to the varying demands placed on them 

Definition
True
Term
What is atrophy?
Definition
decrease in fiber size and number
Term
What can result from disuse and immobilization?
Definition
Atrophy, Loss of endurance and Strength capabilities
Term
Which type of fibers atrophy earlier and are more significant with immobilization? What can help to offset this?
Definition

Type I Fibers.

Electrical Stimulation.

Term
What are the keys to limiting atophy?
Definition
Early mobilization and dynamic exercises
Term
What are 3 Effects of Aging?
Definition

Aging process itself (ie. hormonal changes)

Disuse (ie. hypokinesis)

Other factors (ie. nutrition, pathology, medications)

Term
What is the relationship between physical training and the fibers?
Definition
Training increases the CSA of ALL fibers including size and strength
Term
What is dependent on the kind of training and fibers?
Definition
Percentage of fiber types changes
Term
What are 3 physiologic effects Stretching has on the muscles?
Definition
  • Inhibits the spindle effect (increases muscle contraction in response to stretch)
  • Enhance the Golgi effect (inhibits contraction and enhances relaxation in response to an increase in muscle tension)
  • Adds new sarcomeres in series
Term
Hypertrophy results in what?
Definition
Fiber hypertrophy and Fiber hyperplasia
Supporting users have an ad free experience!