Muscle physiology and anatomy Flashcards
Types of muscles
Cardiac, skeletal, smooth
Smooth Muscle location
Internal organs
Cardiac Muscle location
Heart only
Skeletal Muscle location
Skeleton. Bones by tendon
Striated muscles
Skeletal and Cardiac
Not a striated muscle
Smooth
Muscle with branches
Cardiac
Muscle(s) without branches
Skeletal and Smooth
Which muscle(s) are involuntary?
Cardiac and Smooth
Which muscle is voluntary
Skeletal
The 5 functions of muscles
- Movement,
2.Posture & body position - Support soft tissue
4.Guards body entrances and exits - Maintain body temperature
Actin
Found within thick filaments
Myosin
Found in thin filaments
What is a sacromere
Basic contractile unit of muscle fiber
A Band
Region with thick(and thin) filaments
I Band (i)
Region without thick filaments
H Zone
Region without thin filaments
M Line
Region in the center of the thick filaments purely thick filaments
Step one of Action potential NMJ (Neuromuscular junction)
Action potential is sent from the brain,relasing ACh (acetylcholine into the synaptic cleft. the ACh realesed by neurons tells muscles to move…
Step two of NMJ
ACh binds to ACh receptors on the sarcolemma.Sodium ions move into the sarcoplasm-> action potential in the sacrolemma..
Step three of NMJ
Action potential goes down the T tubules. The action potential causes the cisternae to release calicum ion. Muscle contractions start when the cisternae releases calcium.
Cross Bridge cycling step one
Ca2+ is relased by the sacroplasmic reticulum..
Cross Bridge cycling step two
Ca2+ bidns to the troponin
Cross Bridge cycling step three
The binding of Ca2+ causes troponin to change shape and roll tropmyosin off the myosin-binding sites
Cross Bridge cycling step four
The myosin head cocks, forming a cross-bridge between the mysoin head and the myosin binding site.
Cross Bridge cycling step five
Myosin pulls actin toward the M-line. This is called power-stroke
Cross Bridge cycling step six
ATP binds to myosin, allowing it to break the cross-bridge. Steps 4-6 repeat as long as Ca2+ and ATp are present.
Myofibrils have repeating units called…
Sacromeres!
In a muscle cell, the plasma membrane is called the…?
Sacrolemma
In a muscle cell, the cytoplasm is called the ___
Sacroplasm
Motor Units
The motor unit is a motor neuron and all of the muscle fibers it innervates (stimulates)
Motor Neurons
are cells in the brain and spinal cord that allow us to move, speak, swallow and breathe by sending commands from the brain to the muscles that carry out these functions.
Fine motor control
the coordination of muscles, bones, and nerves to produce small, exact movements.
Gross motor control
The ability to make large, general movements (such as waving an arm or lifting a leg)
Recruitment
the process of increasing the number of motor units to participate in muscle contraction
Muscle contractions
the tightening, shortening, or lengthening of muscles when you do some activity.
Tension
the condition where one or more muscles remains semi-contracted for a prolonged period.
Twitch
A single stimulus-contraction-relaxation sequence of a muscle fiber.
Summation
refers to the fact that if a second stimulus arrives before the relaxation phase has ended, a second, more powerful twitch occurs.
Tetanus
A sustained and continuous contraction when there’s a high frequency of stimulus.
Isotonic muscle contraction
A muscular contraction in which the length of the muscle changes.
Isometric muscle contraction
a muscle contraction without motion.
Isotonic eccentric
involves the muscle lengthening whilst it is under tension.
isotonic concentric
a type of muscle contraction in which the muscles shorten while generating force.
Size principle
as more force is needed, motor units are recruited in a precise order according to the magnitude of their force output,
Phases in Muscle Fiber Stimulation (Single)
Latent phase
- Action potential starts → calcium released
No tension though because contraction hasn’t happened yet
Phases in Muscle Fiber Stimulation (Single)
Contraction phase
2.
Tension peaks because cross-bridge activity is happening
Phases in Muscle Fiber Stimulation (Single)
Relaxation phase
3.
Muscle tension decreases because calcium levels decrease
Number of cross-bridges decreases
Compression
If the sensation you are feeling is coming from tissues being pressed into each other, this is compression. It could include the feeling of one bone rubbing on another.
