Muscle Physiology Flashcards
What happens when the axon potential of the nerve reaches a muscle?
Results in the release of acetylcholine which binds to nicotinic receptors on sarcolemma of muscle fiber
What happens when acetylcholine binds with sarcolemma?
Opens Na channels and causes an ion influx that initiates depolarisation of sarcolemma
What is tension?
Mechanical force a contracting muscle exerts on an object
What must occur for a muscle to shorten?
Muscle tension must exceed the load that opposes it
What is muscle power?
The power proportional to muscle mass and is a measure of the rate of doing work
What is an isotonic contraction?
Tension with movement
What is isometric contraction?
Tension with no movement
What is an example of isotonic contraction?
Bicep curl
What is an example of isometric contraction?
Wall sit or maintaining posture
What is a sarcomere?
Basic contractile unit of muscle fiber
What is the structure of a sarcomere?
Overlapping thin filament attached to z plate with thick filaments with feet in between
What occurs during muscle shortening?
The two set of filaments in the sarcomere sliding past each other with Z plates being pulled towards each other
What is troponin?
The protein attached to tropomyosin which controls the interaction between actin and myosin
What is tropomyosin?
The protein which inhibits interaction between actin and myosin
How does the myosin head bind?
Ca2+ binds to troponin which triggers it to roll away moving tropomyosin out of the way allowing the myosin head bind
In what direction does the depolarisation in sarcolemma occur?
Both directions
How does the thin filament and thick filament move?
The thick filament has myosin head which attaches to the thin filament and bend powered by ATP
How does the myosin head release from the actin?
ATP binds to the myosin head allowing it to release and reset
What happens to the excess Ca2+ in the cytosol?
Ca ATPase pumps remove Ca ions from the cytosol and pump it back to the reticulum
What is a motor unit?
One motor neuron and all the muscle cells that form junctions with its endings
What is the relationship between motor units and fine motor skills?
The more number of motor units the more fine motor control a muscle has
What is spatial summation?
The more number of motor neurons used the greater the muscle tension developed
What is a twitch?
The mechanical response of a muscle fibre to a single action potential
What is the latent period in muscle tension?
The period before the tension begins to increase
What is contraction time?
The time interval from the beginning of tension development to the peak tension
What is passive tension?
The resistance to stretch when a muscle is lengthened beyond its resting length
What is active tension?
The force generated by muscle contraction
What produces maximal contraction?
Continuous sustained fast stimulation known as tetanic contraction
What is muscle fatigue?
When there is not enough ATP to fulfil the continuous stimulation
What are slow twitch muscles?
Muscles that require good stores of energy and are important for stamina
What are fast twitch muscles?
Muscles that are good for short, powerful bursts of energy and do not require lots of stored energy
What is muscle hypertrophy?
Increased growth in the size of the muscle fibers
What is muscle hyperplasia?
Increase of muscle cells
What is muscle atrophy?
The decrease in muscle fiber size
What are the two types of muscle atrophy?
Denervation atrophy and disuse atrophy
What is denervation atrohpy?
Occurs when nerve fibers to muscles are damaged
What is disuse atrophy?
Occurs when muscles are not used for a long period of time
