functional anatomy Flashcards
epimysium:
a layer of connective tissue which covers the entire muscle belly.
fascicle:
the bundle of skeletal muscle fibres. this bundle is surrounded by connective tissue called perimysium.
perimysium:
the connective tissue that surrounds an individual fascicle
muscle fibre:
Cylindrical shape cells that form along the length of the muscle. Bundled with many others to form fascicle/myofibrils.
myofibril:
The part of the muscle in casing the actin and myosin filaments. Long filaments within muscle fibre
myosin:
thick protein filament within the sarcomere
actin:
the protein filament within the sarcomere
sarcomere:
smallest functional unit and their contraction change the muscles length and forces it to shorten.
what are the 10 steps of the sliding filament theory?
- motoneuron stimulans muscle fibre with neural impulse
- calcium ions released from sarcoplasmic reticulum and enters sarcomere
- actin binding sites revealed, for myosin heads to attach
- myosin attaches to actin, creating cross bridges
- ATP broken down at site, stimulates cross bridges
- myosin heads pull actin in, in power strokes causing muscle contractions
- sarcomere shortens as z line comes closer
- H zone and I band decrease in size
- neural impulse stops, calcium goes back to sarcoplasmic reticulum
- myosin heads detach from actin, muscle relaxes
isometric contraction:
the muscle does not change length even though it does produce force. the joint angle also remains the same.
isotonic concentric contactions:
the muscle shortens while developing tension or force and the angle of the joint decreases.
isotonic esentric contentions:
the muscle lengthens as it develops tension or force and the angle of the joint increases.
force length relationship:
The amount of force produced by muscle depends on the length of the muscle. Differing lengths produce differing forces.
Resting length/midpoint of joint angle/optimal length:
Force at this length is the greatest due to optimal overlap of myosin heads and actin binding site.
Full lengthened:
Muscle force generation is low due to minimal overlap of myosin heads and actin binding sites
Fully contracted:
Muscle force generation is low due to the Z line not being able to move any further inwards. No more actin binding sites available to form cross bridges
order of function of nerves, spinal cord, motor unit:
- sensory neuron
- brain
- spinal cord
- motor neuron
- motor unit
sensory neuron:
Receive stimulus via the dendrites of the sensory neuron and pass information on to the cell body of the sensory neuron, onwards towards the brain via axon
brain:
Interpret message or impulse from the sensory neuron and then decides on the action to take. Sends impulse through to spinal cord for movement
spinal cord:
Receives impulse from the brain and passes message onto motor neuron and muscles
motor neuron:
Receives impulse via dendrites at spinal cord processes it at its cell body, suns onto muscle fibres via axon
motor unit:
Motor neuron and all of the muscle fibres that it innovates, motor neuron receives electrical impulse, sends down axon towards muscle fibre for physical movement.
dendrite of sensory neuron:
Receives information from sense receptors and passes it onto cell body of sensory neuron
axon of motor neuron:
Transmits impulses from one cell body and send it to muscle fibres
