Exam 1 Flashcards
why can muscles only pull?
- allows for optimized self alignment which is necessary for the sliding filament theory
- wants to find the shortest line/most efficient way to transfer force
what are kinematics?
the Qualification of Motion
-velocities, spatial relationships to describe and analyze motion
“video of motion (idea)”
what are kinetics?
The Quanitification of Motion
-uses velocities/spatial relationships to analyze forces that effect motions
“video with feel of motion (understand)”
Why are kinematics and kinetics important?
to understand musculoskeltal system to improve human performance and decrease injury.
What are the 3 muscle types?
- smooth (involuntary)
- cardiac (involuntary)
- skeletal (Voluntary with “involuntary or subconcious contractions”
What are the general characteristics of muscle?
Exensibility (stretchy)
Elasticity (return to normal shape)
Excitability/ Irritability (stimulated by an electrical impulse - ex myotatic reflex)
Contractility- ( develops mechanical tension by PULLING)
What should contractility really be referred to?
TENSIONABILITY- because tension is a pulling force
What are the components of Connective tissue?
Endomysium- inner
Perimysium- bungles of fibers –> fasciculi or fasiculus
Epimysium- outer that bundles all the fasiculi together to form complete muscle
what is the vertical depth structure of a muscle?
FIBERS
MYOFIBRILS
MYOFILLAMENTS, slide across eachother
ACTIN- small filaments, active sites for cross bridging
MYOSIN- large filaments, attaching heads
what is the horizontal length structure of muscles?
SARCOMERE- smallest complete unit that can shorten & lengthen
SARCOLEMMA- cells membrane
SARCOPLASM- cell fiber cytoplasm
SR- provides structural support and stim of fibers
T-TUBULES- conduction pathways
TERMINAL CISTERNAE- stored calcium that is pumped into and out of sarcomeres
TRIAD- juntion of t-tubes/ SR and terminal cisternae
Why is it beneficial to have 3 layers of connective tissue?
- insulation: so not all types fire
- absorption: of force/impact
- when muscle shortens- allows for control of hydrolytic pressure from blood/waters fixed volume
Why are each muscle cell multi-nucleated?
for regeneration and reconstruction
During the sliding filament theory, what parts change length?
-muscle,
fiber
myofibrils
NOT MYOFILAMENTS
what important parts of sliding filament theory allow contraction
- available Ca++ in sarcomere
- ATP available for use
- proper alignment of myosin heads to exposed sites on actin
What would happen if there were a t-tubule problem?
- the signals would not be able to reach all the myofibrils inside of the muscle
- muscles would fatigue earlier
- Delayed contractions`
How would the structure of the muscle change if there were a t-tubule problem?
- they would be smaller in diameter and could shrinken so that the signal could get through
- possibly bypass the t-tuble and innervate the muscle itself`
How does skeletal muscle operate by the “myotatic/jerk” reflex?
- it is directly innervate4d by nerves that are stimulated by impulses sent from the brain and spinal cord
- they may be voluntary or involuntary
what is a motor unit?
a group of fibers that are all the same type of fiber
- the fiber types are determined by the composition of the Myosin Filament heads & tyheir response to the activity of ATPase
- all of the fibers are connected to the same nerve
how do contractions occur?
the release of Ca++ inot the sarcomere–>active sites are exposed–>energized myosin heads attach and for cross-bridge
what is ATP’s function in contraction?
to break formed corss-bridges while simutaneously reenergizing the myosin head for further cross-bridge formations on the next properly aligned active site
What controls force production of muscles? (3 things)
- INTENSITY
- the number of motor units being fired, also known as motor unit recruitment.)
- type of motor units firing - FREQUENCY
- rate of nerve impulse to muscle
- twitch
- summation–>pumping calcium into sarcomere
- tetanus –> fused= max force production by a given motor unit (more calcium in sarcomere) - ANTICIPATION OR ACTUAL
- stimulus comes from one or the other
- most often: anticipate –> then the actual force is encountered an make and adjustment
What is the fundamental equation for msucle force production?
Motor Units = Number of Fivers = Number of Cross Bridges
**ultimately determined by number of cross bridges being formed
How is fiber type selected?
determined by force to be overcome
-not always speed of action (*can have high velocity type 1 if it can successfully meet the demand)
Which fiber type has highest aerobic capacity by lowest force production?
Type 1
aka. slow red, slow oxidative, oxidative, slow twitch
